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Diffstat (limited to 'Documentation/blockdev')
| -rw-r--r-- | Documentation/blockdev/00-INDEX | 16 | ||||
| -rw-r--r-- | Documentation/blockdev/README.DAC960 | 756 | ||||
| -rw-r--r-- | Documentation/blockdev/cciss.txt | 171 | ||||
| -rw-r--r-- | Documentation/blockdev/cpqarray.txt | 93 | ||||
| -rw-r--r-- | Documentation/blockdev/floppy.txt | 245 | ||||
| -rw-r--r-- | Documentation/blockdev/nbd.txt | 47 | ||||
| -rw-r--r-- | Documentation/blockdev/paride.txt | 417 | ||||
| -rw-r--r-- | Documentation/blockdev/ramdisk.txt | 165 |
8 files changed, 1910 insertions, 0 deletions
diff --git a/Documentation/blockdev/00-INDEX b/Documentation/blockdev/00-INDEX new file mode 100644 index 00000000000..86f054c4701 --- /dev/null +++ b/Documentation/blockdev/00-INDEX @@ -0,0 +1,16 @@ +00-INDEX + - this file +README.DAC960 + - info on Mylex DAC960/DAC1100 PCI RAID Controller Driver for Linux. +cciss.txt + - info, major/minor #'s for Compaq's SMART Array Controllers. +cpqarray.txt + - info on using Compaq's SMART2 Intelligent Disk Array Controllers. +floppy.txt + - notes and driver options for the floppy disk driver. +nbd.txt + - info on a TCP implementation of a network block device. +paride.txt + - information about the parallel port IDE subsystem. +ramdisk.txt + - short guide on how to set up and use the RAM disk. diff --git a/Documentation/blockdev/README.DAC960 b/Documentation/blockdev/README.DAC960 new file mode 100644 index 00000000000..0e8f618ab53 --- /dev/null +++ b/Documentation/blockdev/README.DAC960 @@ -0,0 +1,756 @@ + Linux Driver for Mylex DAC960/AcceleRAID/eXtremeRAID PCI RAID Controllers + + Version 2.2.11 for Linux 2.2.19 + Version 2.4.11 for Linux 2.4.12 + + PRODUCTION RELEASE + + 11 October 2001 + + Leonard N. Zubkoff + Dandelion Digital + lnz@dandelion.com + + Copyright 1998-2001 by Leonard N. Zubkoff <lnz@dandelion.com> + + + INTRODUCTION + +Mylex, Inc. designs and manufactures a variety of high performance PCI RAID +controllers. Mylex Corporation is located at 34551 Ardenwood Blvd., Fremont, +California 94555, USA and can be reached at 510.796.6100 or on the World Wide +Web at http://www.mylex.com. Mylex Technical Support can be reached by +electronic mail at mylexsup@us.ibm.com, by voice at 510.608.2400, or by FAX at +510.745.7715. Contact information for offices in Europe and Japan is available +on their Web site. + +The latest information on Linux support for DAC960 PCI RAID Controllers, as +well as the most recent release of this driver, will always be available from +my Linux Home Page at URL "http://www.dandelion.com/Linux/". The Linux DAC960 +driver supports all current Mylex PCI RAID controllers including the new +eXtremeRAID 2000/3000 and AcceleRAID 352/170/160 models which have an entirely +new firmware interface from the older eXtremeRAID 1100, AcceleRAID 150/200/250, +and DAC960PJ/PG/PU/PD/PL. See below for a complete controller list as well as +minimum firmware version requirements. For simplicity, in most places this +documentation refers to DAC960 generically rather than explicitly listing all +the supported models. + +Driver bug reports should be sent via electronic mail to "lnz@dandelion.com". +Please include with the bug report the complete configuration messages reported +by the driver at startup, along with any subsequent system messages relevant to +the controller's operation, and a detailed description of your system's +hardware configuration. Driver bugs are actually quite rare; if you encounter +problems with disks being marked offline, for example, please contact Mylex +Technical Support as the problem is related to the hardware configuration +rather than the Linux driver. + +Please consult the RAID controller documentation for detailed information +regarding installation and configuration of the controllers. This document +primarily provides information specific to the Linux support. + + + DRIVER FEATURES + +The DAC960 RAID controllers are supported solely as high performance RAID +controllers, not as interfaces to arbitrary SCSI devices. The Linux DAC960 +driver operates at the block device level, the same level as the SCSI and IDE +drivers. Unlike other RAID controllers currently supported on Linux, the +DAC960 driver is not dependent on the SCSI subsystem, and hence avoids all the +complexity and unnecessary code that would be associated with an implementation +as a SCSI driver. The DAC960 driver is designed for as high a performance as +possible with no compromises or extra code for compatibility with lower +performance devices. The DAC960 driver includes extensive error logging and +online configuration management capabilities. Except for initial configuration +of the controller and adding new disk drives, most everything can be handled +from Linux while the system is operational. + +The DAC960 driver is architected to support up to 8 controllers per system. +Each DAC960 parallel SCSI controller can support up to 15 disk drives per +channel, for a maximum of 60 drives on a four channel controller; the fibre +channel eXtremeRAID 3000 controller supports up to 125 disk drives per loop for +a total of 250 drives. The drives installed on a controller are divided into +one or more "Drive Groups", and then each Drive Group is subdivided further +into 1 to 32 "Logical Drives". Each Logical Drive has a specific RAID Level +and caching policy associated with it, and it appears to Linux as a single +block device. Logical Drives are further subdivided into up to 7 partitions +through the normal Linux and PC disk partitioning schemes. Logical Drives are +also known as "System Drives", and Drive Groups are also called "Packs". Both +terms are in use in the Mylex documentation; I have chosen to standardize on +the more generic "Logical Drive" and "Drive Group". + +DAC960 RAID disk devices are named in the style of the obsolete Device File +System (DEVFS). The device corresponding to Logical Drive D on Controller C +is referred to as /dev/rd/cCdD, and the partitions are called /dev/rd/cCdDp1 +through /dev/rd/cCdDp7. For example, partition 3 of Logical Drive 5 on +Controller 2 is referred to as /dev/rd/c2d5p3. Note that unlike with SCSI +disks the device names will not change in the event of a disk drive failure. +The DAC960 driver is assigned major numbers 48 - 55 with one major number per +controller. The 8 bits of minor number are divided into 5 bits for the Logical +Drive and 3 bits for the partition. + + + SUPPORTED DAC960/AcceleRAID/eXtremeRAID PCI RAID CONTROLLERS + +The following list comprises the supported DAC960, AcceleRAID, and eXtremeRAID +PCI RAID Controllers as of the date of this document. It is recommended that +anyone purchasing a Mylex PCI RAID Controller not in the following table +contact the author beforehand to verify that it is or will be supported. + +eXtremeRAID 3000 + 1 Wide Ultra-2/LVD SCSI channel + 2 External Fibre FC-AL channels + 233MHz StrongARM SA 110 Processor + 64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots) + 32MB/64MB ECC SDRAM Memory + +eXtremeRAID 2000 + 4 Wide Ultra-160 LVD SCSI channels + 233MHz StrongARM SA 110 Processor + 64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots) + 32MB/64MB ECC SDRAM Memory + +AcceleRAID 352 + 2 Wide Ultra-160 LVD SCSI channels + 100MHz Intel i960RN RISC Processor + 64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots) + 32MB/64MB ECC SDRAM Memory + +AcceleRAID 170 + 1 Wide Ultra-160 LVD SCSI channel + 100MHz Intel i960RM RISC Processor + 16MB/32MB/64MB ECC SDRAM Memory + +AcceleRAID 160 (AcceleRAID 170LP) + 1 Wide Ultra-160 LVD SCSI channel + 100MHz Intel i960RS RISC Processor + Built in 16M ECC SDRAM Memory + PCI Low Profile Form Factor - fit for 2U height + +eXtremeRAID 1100 (DAC1164P) + 3 Wide Ultra-2/LVD SCSI channels + 233MHz StrongARM SA 110 Processor + 64 Bit 33MHz PCI (backward compatible with 32 Bit PCI slots) + 16MB/32MB/64MB Parity SDRAM Memory with Battery Backup + +AcceleRAID 250 (DAC960PTL1) + Uses onboard Symbios SCSI chips on certain motherboards + Also includes one onboard Wide Ultra-2/LVD SCSI Channel + 66MHz Intel i960RD RISC Processor + 4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory + +AcceleRAID 200 (DAC960PTL0) + Uses onboard Symbios SCSI chips on certain motherboards + Includes no onboard SCSI Channels + 66MHz Intel i960RD RISC Processor + 4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory + +AcceleRAID 150 (DAC960PRL) + Uses onboard Symbios SCSI chips on certain motherboards + Also includes one onboard Wide Ultra-2/LVD SCSI Channel + 33MHz Intel i960RP RISC Processor + 4MB Parity EDO Memory + +DAC960PJ 1/2/3 Wide Ultra SCSI-3 Channels + 66MHz Intel i960RD RISC Processor + 4MB/8MB/16MB/32MB/64MB/128MB ECC EDO Memory + +DAC960PG 1/2/3 Wide Ultra SCSI-3 Channels + 33MHz Intel i960RP RISC Processor + 4MB/8MB ECC EDO Memory + +DAC960PU 1/2/3 Wide Ultra SCSI-3 Channels + Intel i960CF RISC Processor + 4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory + +DAC960PD 1/2/3 Wide Fast SCSI-2 Channels + Intel i960CF RISC Processor + 4MB/8MB EDRAM or 2MB/4MB/8MB/16MB/32MB DRAM Memory + +DAC960PL 1/2/3 Wide Fast SCSI-2 Channels + Intel i960 RISC Processor + 2MB/4MB/8MB/16MB/32MB DRAM Memory + +DAC960P 1/2/3 Wide Fast SCSI-2 Channels + Intel i960 RISC Processor + 2MB/4MB/8MB/16MB/32MB DRAM Memory + +For the eXtremeRAID 2000/3000 and AcceleRAID 352/170/160, firmware version +6.00-01 or above is required. + +For the eXtremeRAID 1100, firmware version 5.06-0-52 or above is required. + +For the AcceleRAID 250, 200, and 150, firmware version 4.06-0-57 or above is +required. + +For the DAC960PJ and DAC960PG, firmware version 4.06-0-00 or above is required. + +For the DAC960PU, DAC960PD, DAC960PL, and DAC960P, either firmware version +3.51-0-04 or above is required (for dual Flash ROM controllers), or firmware +version 2.73-0-00 or above is required (for single Flash ROM controllers) + +Please note that not all SCSI disk drives are suitable for use with DAC960 +controllers, and only particular firmware versions of any given model may +actually function correctly. Similarly, not all motherboards have a BIOS that +properly initializes the AcceleRAID 250, AcceleRAID 200, AcceleRAID 150, +DAC960PJ, and DAC960PG because the Intel i960RD/RP is a multi-function device. +If in doubt, contact Mylex RAID Technical Support (mylexsup@us.ibm.com) to +verify compatibility. Mylex makes available a hard disk compatibility list at +http://www.mylex.com/support/hdcomp/hd-lists.html. + + + DRIVER INSTALLATION + +This distribution was prepared for Linux kernel version 2.2.19 or 2.4.12. + +To install the DAC960 RAID driver, you may use the following commands, +replacing "/usr/src" with wherever you keep your Linux kernel source tree: + + cd /usr/src + tar -xvzf DAC960-2.2.11.tar.gz (or DAC960-2.4.11.tar.gz) + mv README.DAC960 linux/Documentation + mv DAC960.[ch] linux/drivers/block + patch -p0 < DAC960.patch (if DAC960.patch is included) + cd linux + make config + make bzImage (or zImage) + +Then install "arch/i386/boot/bzImage" or "arch/i386/boot/zImage" as your +standard kernel, run lilo if appropriate, and reboot. + +To create the necessary devices in /dev, the "make_rd" script included in +"DAC960-Utilities.tar.gz" from http://www.dandelion.com/Linux/ may be used. +LILO 21 and FDISK v2.9 include DAC960 support; also included in this archive +are patches to LILO 20 and FDISK v2.8 that add DAC960 support, along with +statically linked executables of LILO and FDISK. This modified version of LILO +will allow booting from a DAC960 controller and/or mounting the root file +system from a DAC960. + +Red Hat Linux 6.0 and SuSE Linux 6.1 include support for Mylex PCI RAID +controllers. Installing directly onto a DAC960 may be problematic from other +Linux distributions until their installation utilities are updated. + + + INSTALLATION NOTES + +Before installing Linux or adding DAC960 logical drives to an existing Linux +system, the controller must first be configured to provide one or more logical +drives using the BIOS Configuration Utility or DACCF. Please note that since +there are only at most 6 usable partitions on each logical drive, systems +requiring more partitions should subdivide a drive group into multiple logical +drives, each of which can have up to 6 usable partitions. Also, note that with +large disk arrays it is advisable to enable the 8GB BIOS Geometry (255/63) +rather than accepting the default 2GB BIOS Geometry (128/32); failing to so do +will cause the logical drive geometry to have more than 65535 cylinders which +will make it impossible for FDISK to be used properly. The 8GB BIOS Geometry +can be enabled by configuring the DAC960 BIOS, which is accessible via Alt-M +during the BIOS initialization sequence. + +For maximum performance and the most efficient E2FSCK performance, it is +recommended that EXT2 file systems be built with a 4KB block size and 16 block +stride to match the DAC960 controller's 64KB default stripe size. The command +"mke2fs -b 4096 -R stride=16 <device>" is appropriate. Unless there will be a +large number of small files on the file systems, it is also beneficial to add +the "-i 16384" option to increase the bytes per inode parameter thereby +reducing the file system metadata. Finally, on systems that will only be run +with Linux 2.2 or later kernels it is beneficial to enable sparse superblocks +with the "-s 1" option. + + + DAC960 ANNOUNCEMENTS MAILING LIST + +The DAC960 Announcements Mailing List provides a forum for informing Linux +users of new driver releases and other announcements regarding Linux support +for DAC960 PCI RAID Controllers. To join the mailing list, send a message to +"dac960-announce-request@dandelion.com" with the line "subscribe" in the +message body. + + + CONTROLLER CONFIGURATION AND STATUS MONITORING + +The DAC960 RAID controllers running firmware 4.06 or above include a Background +Initialization facility so that system downtime is minimized both for initial +installation and subsequent configuration of additional storage. The BIOS +Configuration Utility (accessible via Alt-R during the BIOS initialization +sequence) is used to quickly configure the controller, and then the logical +drives that have been created are available for immediate use even while they +are still being initialized by the controller. The primary need for online +configuration and status monitoring is then to avoid system downtime when disk +drives fail and must be replaced. Mylex's online monitoring and configuration +utilities are being ported to Linux and will become available at some point in +the future. Note that with a SAF-TE (SCSI Accessed Fault-Tolerant Enclosure) +enclosure, the controller is able to rebuild failed drives automatically as +soon as a drive replacement is made available. + +The primary interfaces for controller configuration and status monitoring are +special files created in the /proc/rd/... hierarchy along with the normal +system console logging mechanism. Whenever the system is operating, the DAC960 +driver queries each controller for status information every 10 seconds, and +checks for additional conditions every 60 seconds. The initial status of each +controller is always available for controller N in /proc/rd/cN/initial_status, +and the current status as of the last status monitoring query is available in +/proc/rd/cN/current_status. In addition, status changes are also logged by the +driver to the system console and will appear in the log files maintained by +syslog. The progress of asynchronous rebuild or consistency check operations +is also available in /proc/rd/cN/current_status, and progress messages are +logged to the system console at most every 60 seconds. + +Starting with the 2.2.3/2.0.3 versions of the driver, the status information +available in /proc/rd/cN/initial_status and /proc/rd/cN/current_status has been +augmented to include the vendor, model, revision, and serial number (if +available) for each physical device found connected to the controller: + +***** DAC960 RAID Driver Version 2.2.3 of 19 August 1999 ***** +Copyright 1998-1999 by Leonard N. Zubkoff <lnz@dandelion.com> +Configuring Mylex DAC960PRL PCI RAID Controller + Firmware Version: 4.07-0-07, Channels: 1, Memory Size: 16MB + PCI Bus: 1, Device: 4, Function: 1, I/O Address: Unassigned + PCI Address: 0xFE300000 mapped at 0xA0800000, IRQ Channel: 21 + Controller Queue Depth: 128, Maximum Blocks per Command: 128 + Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33 + Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63 + SAF-TE Enclosure Management Enabled + Physical Devices: + 0:0 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 68016775HA + Disk Status: Online, 17928192 blocks + 0:1 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 68004E53HA + Disk Status: Online, 17928192 blocks + 0:2 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 13013935HA + Disk Status: Online, 17928192 blocks + 0:3 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 13016897HA + Disk Status: Online, 17928192 blocks + 0:4 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 68019905HA + Disk Status: Online, 17928192 blocks + 0:5 Vendor: IBM Model: DRVS09D Revision: 0270 + Serial Number: 68012753HA + Disk Status: Online, 17928192 blocks + 0:6 Vendor: ESG-SHV Model: SCA HSBP M6 Revision: 0.61 + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 89640960 blocks, Write Thru + No Rebuild or Consistency Check in Progress + +To simplify the monitoring process for custom software, the special file +/proc/rd/status returns "OK" when all DAC960 controllers in the system are +operating normally and no failures have occurred, or "ALERT" if any logical +drives are offline or critical or any non-standby physical drives are dead. + +Configuration commands for controller N are available via the special file +/proc/rd/cN/user_command. A human readable command can be written to this +special file to initiate a configuration operation, and the results of the +operation can then be read back from the special file in addition to being +logged to the system console. The shell command sequence + + echo "<configuration-command>" > /proc/rd/c0/user_command + cat /proc/rd/c0/user_command + +is typically used to execute configuration commands. The configuration +commands are: + + flush-cache + + The "flush-cache" command flushes the controller's cache. The system + automatically flushes the cache at shutdown or if the driver module is + unloaded, so this command is only needed to be certain a write back cache + is flushed to disk before the system is powered off by a command to a UPS. + Note that the flush-cache command also stops an asynchronous rebuild or + consistency check, so it should not be used except when the system is being + halted. + + kill <channel>:<target-id> + + The "kill" command marks the physical drive <channel>:<target-id> as DEAD. + This command is provided primarily for testing, and should not be used + during normal system operation. + + make-online <channel>:<target-id> + + The "make-online" command changes the physical drive <channel>:<target-id> + from status DEAD to status ONLINE. In cases where multiple physical drives + have been killed simultaneously, this command may be used to bring all but + one of them back online, after which a rebuild to the final drive is + necessary. + + Warning: make-online should only be used on a dead physical drive that is + an active part of a drive group, never on a standby drive. The command + should never be used on a dead drive that is part of a critical logical + drive; rebuild should be used if only a single drive is dead. + + make-standby <channel>:<target-id> + + The "make-standby" command changes physical drive <channel>:<target-id> + from status DEAD to status STANDBY. It should only be used in cases where + a dead drive was replaced after an automatic rebuild was performed onto a + standby drive. It cannot be used to add a standby drive to the controller + configuration if one was not created initially; the BIOS Configuration + Utility must be used for that currently. + + rebuild <channel>:<target-id> + + The "rebuild" command initiates an asynchronous rebuild onto physical drive + <channel>:<target-id>. It should only be used when a dead drive has been + replaced. + + check-consistency <logical-drive-number> + + The "check-consistency" command initiates an asynchronous consistency check + of <logical-drive-number> with automatic restoration. It can be used + whenever it is desired to verify the consistency of the redundancy + information. + + cancel-rebuild + cancel-consistency-check + + The "cancel-rebuild" and "cancel-consistency-check" commands cancel any + rebuild or consistency check operations previously initiated. + + + EXAMPLE I - DRIVE FAILURE WITHOUT A STANDBY DRIVE + +The following annotated logs demonstrate the controller configuration and and +online status monitoring capabilities of the Linux DAC960 Driver. The test +configuration comprises 6 1GB Quantum Atlas I disk drives on two channels of a +DAC960PJ controller. The physical drives are configured into a single drive +group without a standby drive, and the drive group has been configured into two +logical drives, one RAID-5 and one RAID-6. Note that these logs are from an +earlier version of the driver and the messages have changed somewhat with newer +releases, but the functionality remains similar. First, here is the current +status of the RAID configuration: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status +***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 ***** +Copyright 1998-1999 by Leonard N. Zubkoff <lnz@dandelion.com> +Configuring Mylex DAC960PJ PCI RAID Controller + Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB + PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned + PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9 + Controller Queue Depth: 128, Maximum Blocks per Command: 128 + Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33 + Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63 + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 5498880 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Online, 3305472 blocks, Write Thru + No Rebuild or Consistency Check in Progress + +gwynedd:/u/lnz# cat /proc/rd/status +OK + +The above messages indicate that everything is healthy, and /proc/rd/status +returns "OK" indicating that there are no problems with any DAC960 controller +in the system. For demonstration purposes, while I/O is active Physical Drive +1:1 is now disconnected, simulating a drive failure. The failure is noted by +the driver within 10 seconds of the controller's having detected it, and the +driver logs the following console status messages indicating that Logical +Drives 0 and 1 are now CRITICAL as a result of Physical Drive 1:1 being DEAD: + +DAC960#0: Physical Drive 1:2 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02 +DAC960#0: Physical Drive 1:3 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02 +DAC960#0: Physical Drive 1:1 killed because of timeout on SCSI command +DAC960#0: Physical Drive 1:1 is now DEAD +DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now CRITICAL +DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now CRITICAL + +The Sense Keys logged here are just Check Condition / Unit Attention conditions +arising from a SCSI bus reset that is forced by the controller during its error +recovery procedures. Concurrently with the above, the driver status available +from /proc/rd also reflects the drive failure. The status message in +/proc/rd/status has changed from "OK" to "ALERT": + +gwynedd:/u/lnz# cat /proc/rd/status +ALERT + +and /proc/rd/c0/current_status has been updated: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Dead, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru + No Rebuild or Consistency Check in Progress + +Since there are no standby drives configured, the system can continue to access +the logical drives in a performance degraded mode until the failed drive is +replaced and a rebuild operation completed to restore the redundancy of the +logical drives. Once Physical Drive 1:1 is replaced with a properly +functioning drive, or if the physical drive was killed without having failed +(e.g., due to electrical problems on the SCSI bus), the user can instruct the +controller to initiate a rebuild operation onto the newly replaced drive: + +gwynedd:/u/lnz# echo "rebuild 1:1" > /proc/rd/c0/user_command +gwynedd:/u/lnz# cat /proc/rd/c0/user_command +Rebuild of Physical Drive 1:1 Initiated + +The echo command instructs the controller to initiate an asynchronous rebuild +operation onto Physical Drive 1:1, and the status message that results from the +operation is then available for reading from /proc/rd/c0/user_command, as well +as being logged to the console by the driver. + +Within 10 seconds of this command the driver logs the initiation of the +asynchronous rebuild operation: + +DAC960#0: Rebuild of Physical Drive 1:1 Initiated +DAC960#0: Physical Drive 1:1 Error Log: Sense Key = 6, ASC = 29, ASCQ = 01 +DAC960#0: Physical Drive 1:1 is now WRITE-ONLY +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 1% completed + +and /proc/rd/c0/current_status is updated: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Write-Only, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru + Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 6% completed + +As the rebuild progresses, the current status in /proc/rd/c0/current_status is +updated every 10 seconds: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Write-Only, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Critical, 5498880 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Critical, 3305472 blocks, Write Thru + Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 15% completed + +and every minute a progress message is logged to the console by the driver: + +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 32% completed +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 63% completed +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 94% completed +DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 94% completed + +Finally, the rebuild completes successfully. The driver logs the status of the +logical and physical drives and the rebuild completion: + +DAC960#0: Rebuild Completed Successfully +DAC960#0: Physical Drive 1:1 is now ONLINE +DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now ONLINE +DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now ONLINE + +/proc/rd/c0/current_status is updated: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 5498880 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Online, 3305472 blocks, Write Thru + Rebuild Completed Successfully + +and /proc/rd/status indicates that everything is healthy once again: + +gwynedd:/u/lnz# cat /proc/rd/status +OK + + + EXAMPLE II - DRIVE FAILURE WITH A STANDBY DRIVE + +The following annotated logs demonstrate the controller configuration and and +online status monitoring capabilities of the Linux DAC960 Driver. The test +configuration comprises 6 1GB Quantum Atlas I disk drives on two channels of a +DAC960PJ controller. The physical drives are configured into a single drive +group with a standby drive, and the drive group has been configured into two +logical drives, one RAID-5 and one RAID-6. Note that these logs are from an +earlier version of the driver and the messages have changed somewhat with newer +releases, but the functionality remains similar. First, here is the current +status of the RAID configuration: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status +***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 ***** +Copyright 1998-1999 by Leonard N. Zubkoff <lnz@dandelion.com> +Configuring Mylex DAC960PJ PCI RAID Controller + Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB + PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned + PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9 + Controller Queue Depth: 128, Maximum Blocks per Command: 128 + Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33 + Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63 + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Online, 2201600 blocks + 1:3 - Disk: Standby, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru + No Rebuild or Consistency Check in Progress + +gwynedd:/u/lnz# cat /proc/rd/status +OK + +The above messages indicate that everything is healthy, and /proc/rd/status +returns "OK" indicating that there are no problems with any DAC960 controller +in the system. For demonstration purposes, while I/O is active Physical Drive +1:2 is now disconnected, simulating a drive failure. The failure is noted by +the driver within 10 seconds of the controller's having detected it, and the +driver logs the following console status messages: + +DAC960#0: Physical Drive 1:1 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02 +DAC960#0: Physical Drive 1:3 Error Log: Sense Key = 6, ASC = 29, ASCQ = 02 +DAC960#0: Physical Drive 1:2 killed because of timeout on SCSI command +DAC960#0: Physical Drive 1:2 is now DEAD +DAC960#0: Physical Drive 1:2 killed because it was removed +DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now CRITICAL +DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now CRITICAL + +Since a standby drive is configured, the controller automatically begins +rebuilding onto the standby drive: + +DAC960#0: Physical Drive 1:3 is now WRITE-ONLY +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 4% completed + +Concurrently with the above, the driver status available from /proc/rd also +reflects the drive failure and automatic rebuild. The status message in +/proc/rd/status has changed from "OK" to "ALERT": + +gwynedd:/u/lnz# cat /proc/rd/status +ALERT + +and /proc/rd/c0/current_status has been updated: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Dead, 2201600 blocks + 1:3 - Disk: Write-Only, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Critical, 4399104 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Critical, 2754560 blocks, Write Thru + Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 4% completed + +As the rebuild progresses, the current status in /proc/rd/c0/current_status is +updated every 10 seconds: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Dead, 2201600 blocks + 1:3 - Disk: Write-Only, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Critical, 4399104 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Critical, 2754560 blocks, Write Thru + Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 40% completed + +and every minute a progress message is logged on the console by the driver: + +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 40% completed +DAC960#0: Rebuild in Progress: Logical Drive 0 (/dev/rd/c0d0) 76% completed +DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 66% completed +DAC960#0: Rebuild in Progress: Logical Drive 1 (/dev/rd/c0d1) 84% completed + +Finally, the rebuild completes successfully. The driver logs the status of the +logical and physical drives and the rebuild completion: + +DAC960#0: Rebuild Completed Successfully +DAC960#0: Physical Drive 1:3 is now ONLINE +DAC960#0: Logical Drive 0 (/dev/rd/c0d0) is now ONLINE +DAC960#0: Logical Drive 1 (/dev/rd/c0d1) is now ONLINE + +/proc/rd/c0/current_status is updated: + +***** DAC960 RAID Driver Version 2.0.0 of 23 March 1999 ***** +Copyright 1998-1999 by Leonard N. Zubkoff <lnz@dandelion.com> +Configuring Mylex DAC960PJ PCI RAID Controller + Firmware Version: 4.06-0-08, Channels: 3, Memory Size: 8MB + PCI Bus: 0, Device: 19, Function: 1, I/O Address: Unassigned + PCI Address: 0xFD4FC000 mapped at 0x8807000, IRQ Channel: 9 + Controller Queue Depth: 128, Maximum Blocks per Command: 128 + Driver Queue Depth: 127, Maximum Scatter/Gather Segments: 33 + Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63 + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Dead, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru + Rebuild Completed Successfully + +and /proc/rd/status indicates that everything is healthy once again: + +gwynedd:/u/lnz# cat /proc/rd/status +OK + +Note that the absence of a viable standby drive does not create an "ALERT" +status. Once dead Physical Drive 1:2 has been replaced, the controller must be +told that this has occurred and that the newly replaced drive should become the +new standby drive: + +gwynedd:/u/lnz# echo "make-standby 1:2" > /proc/rd/c0/user_command +gwynedd:/u/lnz# cat /proc/rd/c0/user_command +Make Standby of Physical Drive 1:2 Succeeded + +The echo command instructs the controller to make Physical Drive 1:2 into a +standby drive, and the status message that results from the operation is then +available for reading from /proc/rd/c0/user_command, as well as being logged to +the console by the driver. Within 60 seconds of this command the driver logs: + +DAC960#0: Physical Drive 1:2 Error Log: Sense Key = 6, ASC = 29, ASCQ = 01 +DAC960#0: Physical Drive 1:2 is now STANDBY +DAC960#0: Make Standby of Physical Drive 1:2 Succeeded + +and /proc/rd/c0/current_status is updated: + +gwynedd:/u/lnz# cat /proc/rd/c0/current_status + ... + Physical Devices: + 0:1 - Disk: Online, 2201600 blocks + 0:2 - Disk: Online, 2201600 blocks + 0:3 - Disk: Online, 2201600 blocks + 1:1 - Disk: Online, 2201600 blocks + 1:2 - Disk: Standby, 2201600 blocks + 1:3 - Disk: Online, 2201600 blocks + Logical Drives: + /dev/rd/c0d0: RAID-5, Online, 4399104 blocks, Write Thru + /dev/rd/c0d1: RAID-6, Online, 2754560 blocks, Write Thru + Rebuild Completed Successfully diff --git a/Documentation/blockdev/cciss.txt b/Documentation/blockdev/cciss.txt new file mode 100644 index 00000000000..89698e8df7d --- /dev/null +++ b/Documentation/blockdev/cciss.txt @@ -0,0 +1,171 @@ +This driver is for Compaq's SMART Array Controllers. + +Supported Cards: +---------------- + +This driver is known to work with the following cards: + + * SA 5300 + * SA 5i + * SA 532 + * SA 5312 + * SA 641 + * SA 642 + * SA 6400 + * SA 6400 U320 Expansion Module + * SA 6i + * SA P600 + * SA P800 + * SA E400 + * SA P400i + * SA E200 + * SA E200i + * SA E500 + * SA P700m + * SA P212 + * SA P410 + * SA P410i + * SA P411 + * SA P812 + * SA P712m + * SA P711m + +Detecting drive failures: +------------------------- + +To get the status of logical volumes and to detect physical drive +failures, you can use the cciss_vol_status program found here: +http://cciss.sourceforge.net/#cciss_utils + +Device Naming: +-------------- + +If nodes are not already created in the /dev/cciss directory, run as root: + +# cd /dev +# ./MAKEDEV cciss + +You need some entries in /dev for the cciss device. The MAKEDEV script +can make device nodes for you automatically. Currently the device setup +is as follows: + +Major numbers: + 104 cciss0 + 105 cciss1 + 106 cciss2 + 105 cciss3 + 108 cciss4 + 109 cciss5 + 110 cciss6 + 111 cciss7 + +Minor numbers: + b7 b6 b5 b4 b3 b2 b1 b0 + |----+----| |----+----| + | | + | +-------- Partition ID (0=wholedev, 1-15 partition) + | + +-------------------- Logical Volume number + +The device naming scheme is: +/dev/cciss/c0d0 Controller 0, disk 0, whole device +/dev/cciss/c0d0p1 Controller 0, disk 0, partition 1 +/dev/cciss/c0d0p2 Controller 0, disk 0, partition 2 +/dev/cciss/c0d0p3 Controller 0, disk 0, partition 3 + +/dev/cciss/c1d1 Controller 1, disk 1, whole device +/dev/cciss/c1d1p1 Controller 1, disk 1, partition 1 +/dev/cciss/c1d1p2 Controller 1, disk 1, partition 2 +/dev/cciss/c1d1p3 Controller 1, disk 1, partition 3 + +SCSI tape drive and medium changer support +------------------------------------------ + +SCSI sequential access devices and medium changer devices are supported and +appropriate device nodes are automatically created. (e.g. +/dev/st0, /dev/st1, etc. See the "st" man page for more details.) +You must enable "SCSI tape drive support for Smart Array 5xxx" and +"SCSI support" in your kernel configuration to be able to use SCSI +tape drives with your Smart Array 5xxx controller. + +Additionally, note that the driver will not engage the SCSI core at init +time. The driver must be directed to dynamically engage the SCSI core via +the /proc filesystem entry which the "block" side of the driver creates as +/proc/driver/cciss/cciss* at runtime. This is because at driver init time, +the SCSI core may not yet be initialized (because the driver is a block +driver) and attempting to register it with the SCSI core in such a case +would cause a hang. This is best done via an initialization script +(typically in /etc/init.d, but could vary depending on distribution). +For example: + + for x in /proc/driver/cciss/cciss[0-9]* + do + echo "engage scsi" > $x + done + +Once the SCSI core is engaged by the driver, it cannot be disengaged +(except by unloading the driver, if it happens to be linked as a module.) + +Note also that if no sequential access devices or medium changers are +detected, the SCSI core will not be engaged by the action of the above +script. + +Hot plug support for SCSI tape drives +------------------------------------- + +Hot plugging of SCSI tape drives is supported, with some caveats. +The cciss driver must be informed that changes to the SCSI bus +have been made. This may be done via the /proc filesystem. +For example: + + echo "rescan" > /proc/scsi/cciss0/1 + +This causes the driver to query the adapter about changes to the +physical SCSI buses and/or fibre channel arbitrated loop and the +driver to make note of any new or removed sequential access devices +or medium changers. The driver will output messages indicating what +devices have been added or removed and the controller, bus, target and +lun used to address the device. It then notifies the SCSI mid layer +of these changes. + +Note that the naming convention of the /proc filesystem entries +contains a number in addition to the driver name. (E.g. "cciss0" +instead of just "cciss" which you might expect.) + +Note: ONLY sequential access devices and medium changers are presented +as SCSI devices to the SCSI mid layer by the cciss driver. Specifically, +physical SCSI disk drives are NOT presented to the SCSI mid layer. The +physical SCSI disk drives are controlled directly by the array controller +hardware and it is important to prevent the kernel from attempting to directly +access these devices too, as if the array controller were merely a SCSI +controller in the same way that we are allowing it to access SCSI tape drives. + +SCSI error handling for tape drives and medium changers +------------------------------------------------------- + +The linux SCSI mid layer provides an error handling protocol which +kicks into gear whenever a SCSI command fails to complete within a +certain amount of time (which can vary depending on the command). +The cciss driver participates in this protocol to some extent. The +normal protocol is a four step process. First the device is told +to abort the command. If that doesn't work, the device is reset. +If that doesn't work, the SCSI bus is reset. If that doesn't work +the host bus adapter is reset. Because the cciss driver is a block +driver as well as a SCSI driver and only the tape drives and medium +changers are presented to the SCSI mid layer, and unlike more +straightforward SCSI drivers, disk i/o continues through the block +side during the SCSI error recovery process, the cciss driver only +implements the first two of these actions, aborting the command, and +resetting the device. Additionally, most tape drives will not oblige +in aborting commands, and sometimes it appears they will not even +obey a reset command, though in most circumstances they will. In +the case that the command cannot be aborted and the device cannot be +reset, the device will be set offline. + +In the event the error handling code is triggered and a tape drive is +successfully reset or the tardy command is successfully aborted, the +tape drive may still not allow i/o to continue until some command +is issued which positions the tape to a known position. Typically you +must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example) +before i/o can proceed again to a tape drive which was reset. + diff --git a/Documentation/blockdev/cpqarray.txt b/Documentation/blockdev/cpqarray.txt new file mode 100644 index 00000000000..c7154e20ef5 --- /dev/null +++ b/Documentation/blockdev/cpqarray.txt @@ -0,0 +1,93 @@ +This driver is for Compaq's SMART2 Intelligent Disk Array Controllers. + +Supported Cards: +---------------- + +This driver is known to work with the following cards: + + * SMART (EISA) + * SMART-2/E (EISA) + * SMART-2/P + * SMART-2DH + * SMART-2SL + * SMART-221 + * SMART-3100ES + * SMART-3200 + * Integrated Smart Array Controller + * SA 4200 + * SA 4250ES + * SA 431 + * RAID LC2 Controller + +It should also work with some really old Disk array adapters, but I am +unable to test against these cards: + + * IDA + * IDA-2 + * IAES + + +EISA Controllers: +----------------- + +If you want to use an EISA controller you'll have to supply some +modprobe/lilo parameters. If the driver is compiled into the kernel, must +give it the controller's IO port address at boot time (it is not +necessary to specify the IRQ). For example, if you had two SMART-2/E +controllers, in EISA slots 1 and 2 you'd give it a boot argument like +this: + + smart2=0x1000,0x2000 + +If you were loading the driver as a module, you'd give load it like this: + + modprobe cpqarray eisa=0x1000,0x2000 + +You can use EISA and PCI adapters at the same time. + + +Device Naming: +-------------- + +You need some entries in /dev for the ida device. MAKEDEV in the /dev +directory can make device nodes for you automatically. The device setup is +as follows: + +Major numbers: + 72 ida0 + 73 ida1 + 74 ida2 + 75 ida3 + 76 ida4 + 77 ida5 + 78 ida6 + 79 ida7 + +Minor numbers: + b7 b6 b5 b4 b3 b2 b1 b0 + |----+----| |----+----| + | | + | +-------- Partition ID (0=wholedev, 1-15 partition) + | + +-------------------- Logical Volume number + +The device naming scheme is: +/dev/ida/c0d0 Controller 0, disk 0, whole device +/dev/ida/c0d0p1 Controller 0, disk 0, partition 1 +/dev/ida/c0d0p2 Controller 0, disk 0, partition 2 +/dev/ida/c0d0p3 Controller 0, disk 0, partition 3 + +/dev/ida/c1d1 Controller 1, disk 1, whole device +/dev/ida/c1d1p1 Controller 1, disk 1, partition 1 +/dev/ida/c1d1p2 Controller 1, disk 1, partition 2 +/dev/ida/c1d1p3 Controller 1, disk 1, partition 3 + + +Changelog: +========== + +10-28-2004 : General cleanup, syntax fixes for in-kernel driver version. + James Nelson <james4765@gmail.com> + + +1999 : Original Document diff --git a/Documentation/blockdev/floppy.txt b/Documentation/blockdev/floppy.txt new file mode 100644 index 00000000000..6ccab88705c --- /dev/null +++ b/Documentation/blockdev/floppy.txt @@ -0,0 +1,245 @@ +This file describes the floppy driver. + +FAQ list: +========= + + A FAQ list may be found in the fdutils package (see below), and also +at <http://fdutils.linux.lu/faq.html>. + + +LILO configuration options (Thinkpad users, read this) +====================================================== + + The floppy driver is configured using the 'floppy=' option in +lilo. This option can be typed at the boot prompt, or entered in the +lilo configuration file. + + Example: If your kernel is called linux-2.6.9, type the following line +at the lilo boot prompt (if you have a thinkpad): + + linux-2.6.9 floppy=thinkpad + +You may also enter the following line in /etc/lilo.conf, in the description +of linux-2.6.9: + + append = "floppy=thinkpad" + + Several floppy related options may be given, example: + + linux-2.6.9 floppy=daring floppy=two_fdc + append = "floppy=daring floppy=two_fdc" + + If you give options both in the lilo config file and on the boot +prompt, the option strings of both places are concatenated, the boot +prompt options coming last. That's why there are also options to +restore the default behavior. + + +Module configuration options +============================ + + If you use the floppy driver as a module, use the following syntax: +modprobe floppy <options> + +Example: + modprobe floppy omnibook messages + + If you need certain options enabled every time you load the floppy driver, +you can put: + + options floppy omnibook messages + +in /etc/modprobe.conf. + + + The floppy driver related options are: + + floppy=asus_pci + Sets the bit mask to allow only units 0 and 1. (default) + + floppy=daring + Tells the floppy driver that you have a well behaved floppy controller. + This allows more efficient and smoother operation, but may fail on + certain controllers. This may speed up certain operations. + + floppy=0,daring + Tells the floppy driver that your floppy controller should be used + with caution. + + floppy=one_fdc + Tells the floppy driver that you have only one floppy controller. + (default) + + floppy=two_fdc + floppy=<address>,two_fdc + Tells the floppy driver that you have two floppy controllers. + The second floppy controller is assumed to be at <address>. + This option is not needed if the second controller is at address + 0x370, and if you use the 'cmos' option. + + floppy=thinkpad + Tells the floppy driver that you have a Thinkpad. Thinkpads use an + inverted convention for the disk change line. + + floppy=0,thinkpad + Tells the floppy driver that you don't have a Thinkpad. + + floppy=omnibook + floppy=nodma + Tells the floppy driver not to use Dma for data transfers. + This is needed on HP Omnibooks, which don't have a workable + DMA channel for the floppy driver. This option is also useful + if you frequently get "Unable to allocate DMA memory" messages. + Indeed, dma memory needs to be continuous in physical memory, + and is thus harder to find, whereas non-dma buffers may be + allocated in virtual memory. However, I advise against this if + you have an FDC without a FIFO (8272A or 82072). 82072A and + later are OK. You also need at least a 486 to use nodma. + If you use nodma mode, I suggest you also set the FIFO + threshold to 10 or lower, in order to limit the number of data + transfer interrupts. + + If you have a FIFO-able FDC, the floppy driver automatically + falls back on non DMA mode if no DMA-able memory can be found. + If you want to avoid this, explicitly ask for 'yesdma'. + + floppy=yesdma + Tells the floppy driver that a workable DMA channel is available. + (default) + + floppy=nofifo + Disables the FIFO entirely. This is needed if you get "Bus + master arbitration error" messages from your Ethernet card (or + from other devices) while accessing the floppy. + + floppy=usefifo + Enables the FIFO. (default) + + floppy=<threshold>,fifo_depth + Sets the FIFO threshold. This is mostly relevant in DMA + mode. If this is higher, the floppy driver tolerates more + interrupt latency, but it triggers more interrupts (i.e. it + imposes more load on the rest of the system). If this is + lower, the interrupt latency should be lower too (faster + processor). The benefit of a lower threshold is less + interrupts. + + To tune the fifo threshold, switch on over/underrun messages + using 'floppycontrol --messages'. Then access a floppy + disk. If you get a huge amount of "Over/Underrun - retrying" + messages, then the fifo threshold is too low. Try with a + higher value, until you only get an occasional Over/Underrun. + It is a good idea to compile the floppy driver as a module + when doing this tuning. Indeed, it allows to try different + fifo values without rebooting the machine for each test. Note + that you need to do 'floppycontrol --messages' every time you + re-insert the module. + + Usually, tuning the fifo threshold should not be needed, as + the default (0xa) is reasonable. + + floppy=<drive>,<type>,cmos + Sets the CMOS type of <drive> to <type>. This is mandatory if + you have more than two floppy drives (only two can be + described in the physical CMOS), or if your BIOS uses + non-standard CMOS types. The CMOS types are: + + 0 - Use the value of the physical CMOS + 1 - 5 1/4 DD + 2 - 5 1/4 HD + 3 - 3 1/2 DD + 4 - 3 1/2 HD + 5 - 3 1/2 ED + 6 - 3 1/2 ED + 16 - unknown or not installed + + (Note: there are two valid types for ED drives. This is because 5 was + initially chosen to represent floppy *tapes*, and 6 for ED drives. + AMI ignored this, and used 5 for ED drives. That's why the floppy + driver handles both.) + + floppy=unexpected_interrupts + Print a warning message when an unexpected interrupt is received. + (default) + + floppy=no_unexpected_interrupts + floppy=L40SX + Don't print a message when an unexpected interrupt is received. This + is needed on IBM L40SX laptops in certain video modes. (There seems + to be an interaction between video and floppy. The unexpected + interrupts affect only performance, and can be safely ignored.) + + floppy=broken_dcl + Don't use the disk change line, but assume that the disk was + changed whenever the device node is reopened. Needed on some + boxes where the disk change line is broken or unsupported. + This should be regarded as a stopgap measure, indeed it makes + floppy operation less efficient due to unneeded cache + flushings, and slightly more unreliable. Please verify your + cable, connection and jumper settings if you have any DCL + problems. However, some older drives, and also some laptops + are known not to have a DCL. + + floppy=debug + Print debugging messages. + + floppy=messages + Print informational messages for some operations (disk change + notifications, warnings about over and underruns, and about + autodetection). + + floppy=silent_dcl_clear + Uses a less noisy way to clear the disk change line (which + doesn't involve seeks). Implied by 'daring' option. + + floppy=<nr>,irq + Sets the floppy IRQ to <nr> instead of 6. + + floppy=<nr>,dma + Sets the floppy DMA channel to <nr> instead of 2. + + floppy=slow + Use PS/2 stepping rate: + " PS/2 floppies have much slower step rates than regular floppies. + It's been recommended that take about 1/4 of the default speed + in some more extreme cases." + + +Supporting utilities and additional documentation: +================================================== + + Additional parameters of the floppy driver can be configured at +runtime. Utilities which do this can be found in the fdutils package. +This package also contains a new version of mtools which allows to +access high capacity disks (up to 1992K on a high density 3 1/2 disk!). +It also contains additional documentation about the floppy driver. + +The latest version can be found at fdutils homepage: + http://fdutils.linux.lu + +The fdutils releases can be found at: + http://fdutils.linux.lu/download.html + http://www.tux.org/pub/knaff/fdutils/ + ftp://metalab.unc.edu/pub/Linux/utils/disk-management/ + +Reporting problems about the floppy driver +========================================== + + If you have a question or a bug report about the floppy driver, mail +me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use +comp.os.linux.hardware. As the volume in these groups is rather high, +be sure to include the word "floppy" (or "FLOPPY") in the subject +line. If the reported problem happens when mounting floppy disks, be +sure to mention also the type of the filesystem in the subject line. + + Be sure to read the FAQ before mailing/posting any bug reports! + + Alain + +Changelog +========= + +10-30-2004 : Cleanup, updating, add reference to module configuration. + James Nelson <james4765@gmail.com> + +6-3-2000 : Original Document diff --git a/Documentation/blockdev/nbd.txt b/Documentation/blockdev/nbd.txt new file mode 100644 index 00000000000..aeb93ffe641 --- /dev/null +++ b/Documentation/blockdev/nbd.txt @@ -0,0 +1,47 @@ + Network Block Device (TCP version) + + What is it: With this compiled in the kernel (or as a module), Linux + can use a remote server as one of its block devices. So every time + the client computer wants to read, e.g., /dev/nb0, it sends a + request over TCP to the server, which will reply with the data read. + This can be used for stations with low disk space (or even diskless - + if you boot from floppy) to borrow disk space from another computer. + Unlike NFS, it is possible to put any filesystem on it, etc. It should + even be possible to use NBD as a root filesystem (I've never tried), + but it requires a user-level program to be in the initrd to start. + It also allows you to run block-device in user land (making server + and client physically the same computer, communicating using loopback). + + Current state: It currently works. Network block device is stable. + I originally thought that it was impossible to swap over TCP. It + turned out not to be true - swapping over TCP now works and seems + to be deadlock-free, but it requires heavy patches into Linux's + network layer. + + For more information, or to download the nbd-client and nbd-server + tools, go to http://nbd.sf.net/. + + Howto: To setup nbd, you can simply do the following: + + First, serve a device or file from a remote server: + + nbd-server <port-number> <device-or-file-to-serve-to-client> + + e.g., + root@server1 # nbd-server 1234 /dev/sdb1 + + (serves sdb1 partition on TCP port 1234) + + Then, on the local (client) system: + + nbd-client <server-name-or-IP> <server-port-number> /dev/nb[0-n] + + e.g., + root@client1 # nbd-client server1 1234 /dev/nb0 + + (creates the nb0 device on client1) + + The nbd kernel module need only be installed on the client + system, as the nbd-server is completely in userspace. In fact, + the nbd-server has been successfully ported to other operating + systems, including Windows. diff --git a/Documentation/blockdev/paride.txt b/Documentation/blockdev/paride.txt new file mode 100644 index 00000000000..e4312676bdd --- /dev/null +++ b/Documentation/blockdev/paride.txt @@ -0,0 +1,417 @@ + + Linux and parallel port IDE devices + +PARIDE v1.03 (c) 1997-8 Grant Guenther <grant@torque.net> + +1. Introduction + +Owing to the simplicity and near universality of the parallel port interface +to personal computers, many external devices such as portable hard-disk, +CD-ROM, LS-120 and tape drives use the parallel port to connect to their +host computer. While some devices (notably scanners) use ad-hoc methods +to pass commands and data through the parallel port interface, most +external devices are actually identical to an internal model, but with +a parallel-port adapter chip added in. Some of the original parallel port +adapters were little more than mechanisms for multiplexing a SCSI bus. +(The Iomega PPA-3 adapter used in the ZIP drives is an example of this +approach). Most current designs, however, take a different approach. +The adapter chip reproduces a small ISA or IDE bus in the external device +and the communication protocol provides operations for reading and writing +device registers, as well as data block transfer functions. Sometimes, +the device being addressed via the parallel cable is a standard SCSI +controller like an NCR 5380. The "ditto" family of external tape +drives use the ISA replicator to interface a floppy disk controller, +which is then connected to a floppy-tape mechanism. The vast majority +of external parallel port devices, however, are now based on standard +IDE type devices, which require no intermediate controller. If one +were to open up a parallel port CD-ROM drive, for instance, one would +find a standard ATAPI CD-ROM drive, a power supply, and a single adapter +that interconnected a standard PC parallel port cable and a standard +IDE cable. It is usually possible to exchange the CD-ROM device with +any other device using the IDE interface. + +The document describes the support in Linux for parallel port IDE +devices. It does not cover parallel port SCSI devices, "ditto" tape +drives or scanners. Many different devices are supported by the +parallel port IDE subsystem, including: + + MicroSolutions backpack CD-ROM + MicroSolutions backpack PD/CD + MicroSolutions backpack hard-drives + MicroSolutions backpack 8000t tape drive + SyQuest EZ-135, EZ-230 & SparQ drives + Avatar Shark + Imation Superdisk LS-120 + Maxell Superdisk LS-120 + FreeCom Power CD + Hewlett-Packard 5GB and 8GB tape drives + Hewlett-Packard 7100 and 7200 CD-RW drives + +as well as most of the clone and no-name products on the market. + +To support such a wide range of devices, PARIDE, the parallel port IDE +subsystem, is actually structured in three parts. There is a base +paride module which provides a registry and some common methods for +accessing the parallel ports. The second component is a set of +high-level drivers for each of the different types of supported devices: + + pd IDE disk + pcd ATAPI CD-ROM + pf ATAPI disk + pt ATAPI tape + pg ATAPI generic + +(Currently, the pg driver is only used with CD-R drives). + +The high-level drivers function according to the relevant standards. +The third component of PARIDE is a set of low-level protocol drivers +for each of the parallel port IDE adapter chips. Thanks to the interest +and encouragement of Linux users from many parts of the world, +support is available for almost all known adapter protocols: + + aten ATEN EH-100 (HK) + bpck Microsolutions backpack (US) + comm DataStor (old-type) "commuter" adapter (TW) + dstr DataStor EP-2000 (TW) + epat Shuttle EPAT (UK) + epia Shuttle EPIA (UK) + fit2 FIT TD-2000 (US) + fit3 FIT TD-3000 (US) + friq Freecom IQ cable (DE) + frpw Freecom Power (DE) + kbic KingByte KBIC-951A and KBIC-971A (TW) + ktti KT Technology PHd adapter (SG) + on20 OnSpec 90c20 (US) + on26 OnSpec 90c26 (US) + + +2. Using the PARIDE subsystem + +While configuring the Linux kernel, you may choose either to build +the PARIDE drivers into your kernel, or to build them as modules. + +In either case, you will need to select "Parallel port IDE device support" +as well as at least one of the high-level drivers and at least one +of the parallel port communication protocols. If you do not know +what kind of parallel port adapter is used in your drive, you could +begin by checking the file names and any text files on your DOS +installation floppy. Alternatively, you can look at the markings on +the adapter chip itself. That's usually sufficient to identify the +correct device. + +You can actually select all the protocol modules, and allow the PARIDE +subsystem to try them all for you. + +For the "brand-name" products listed above, here are the protocol +and high-level drivers that you would use: + + Manufacturer Model Driver Protocol + + MicroSolutions CD-ROM pcd bpck + MicroSolutions PD drive pf bpck + MicroSolutions hard-drive pd bpck + MicroSolutions 8000t tape pt bpck + SyQuest EZ, SparQ pd epat + Imation Superdisk pf epat + Maxell Superdisk pf friq + Avatar Shark pd epat + FreeCom CD-ROM pcd frpw + Hewlett-Packard 5GB Tape pt epat + Hewlett-Packard 7200e (CD) pcd epat + Hewlett-Packard 7200e (CD-R) pg epat + +2.1 Configuring built-in drivers + +We recommend that you get to know how the drivers work and how to +configure them as loadable modules, before attempting to compile a +kernel with the drivers built-in. + +If you built all of your PARIDE support directly into your kernel, +and you have just a single parallel port IDE device, your kernel should +locate it automatically for you. If you have more than one device, +you may need to give some command line options to your bootloader +(eg: LILO), how to do that is beyond the scope of this document. + +The high-level drivers accept a number of command line parameters, all +of which are documented in the source files in linux/drivers/block/paride. +By default, each driver will automatically try all parallel ports it +can find, and all protocol types that have been installed, until it finds +a parallel port IDE adapter. Once it finds one, the probe stops. So, +if you have more than one device, you will need to tell the drivers +how to identify them. This requires specifying the port address, the +protocol identification number and, for some devices, the drive's +chain ID. While your system is booting, a number of messages are +displayed on the console. Like all such messages, they can be +reviewed with the 'dmesg' command. Among those messages will be +some lines like: + + paride: bpck registered as protocol 0 + paride: epat registered as protocol 1 + +The numbers will always be the same until you build a new kernel with +different protocol selections. You should note these numbers as you +will need them to identify the devices. + +If you happen to be using a MicroSolutions backpack device, you will +also need to know the unit ID number for each drive. This is usually +the last two digits of the drive's serial number (but read MicroSolutions' +documentation about this). + +As an example, let's assume that you have a MicroSolutions PD/CD drive +with unit ID number 36 connected to the parallel port at 0x378, a SyQuest +EZ-135 connected to the chained port on the PD/CD drive and also an +Imation Superdisk connected to port 0x278. You could give the following +options on your boot command: + + pd.drive0=0x378,1 pf.drive0=0x278,1 pf.drive1=0x378,0,36 + +In the last option, pf.drive1 configures device /dev/pf1, the 0x378 +is the parallel port base address, the 0 is the protocol registration +number and 36 is the chain ID. + +Please note: while PARIDE will work both with and without the +PARPORT parallel port sharing system that is included by the +"Parallel port support" option, PARPORT must be included and enabled +if you want to use chains of devices on the same parallel port. + +2.2 Loading and configuring PARIDE as modules + +It is much faster and simpler to get to understand the PARIDE drivers +if you use them as loadable kernel modules. + +Note 1: using these drivers with the "kerneld" automatic module loading +system is not recommended for beginners, and is not documented here. + +Note 2: if you build PARPORT support as a loadable module, PARIDE must +also be built as loadable modules, and PARPORT must be loaded before the +PARIDE modules. + +To use PARIDE, you must begin by + + insmod paride + +this loads a base module which provides a registry for the protocols, +among other tasks. + +Then, load as many of the protocol modules as you think you might need. +As you load each module, it will register the protocols that it supports, +and print a log message to your kernel log file and your console. For +example: + + # insmod epat + paride: epat registered as protocol 0 + # insmod kbic + paride: k951 registered as protocol 1 + paride: k971 registered as protocol 2 + +Finally, you can load high-level drivers for each kind of device that +you have connected. By default, each driver will autoprobe for a single +device, but you can support up to four similar devices by giving their +individual co-ordinates when you load the driver. + +For example, if you had two no-name CD-ROM drives both using the +KingByte KBIC-951A adapter, one on port 0x378 and the other on 0x3bc +you could give the following command: + + # insmod pcd drive0=0x378,1 drive1=0x3bc,1 + +For most adapters, giving a port address and protocol number is sufficient, +but check the source files in linux/drivers/block/paride for more +information. (Hopefully someone will write some man pages one day !). + +As another example, here's what happens when PARPORT is installed, and +a SyQuest EZ-135 is attached to port 0x378: + + # insmod paride + paride: version 1.0 installed + # insmod epat + paride: epat registered as protocol 0 + # insmod pd + pd: pd version 1.0, major 45, cluster 64, nice 0 + pda: Sharing parport1 at 0x378 + pda: epat 1.0, Shuttle EPAT chip c3 at 0x378, mode 5 (EPP-32), delay 1 + pda: SyQuest EZ135A, 262144 blocks [128M], (512/16/32), removable media + pda: pda1 + +Note that the last line is the output from the generic partition table +scanner - in this case it reports that it has found a disk with one partition. + +2.3 Using a PARIDE device + +Once the drivers have been loaded, you can access PARIDE devices in the +same way as their traditional counterparts. You will probably need to +create the device "special files". Here is a simple script that you can +cut to a file and execute: + +#!/bin/bash +# +# mkd -- a script to create the device special files for the PARIDE subsystem +# +function mkdev { + mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1 +} +# +function pd { + D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) ) + mkdev pd$D b 45 $[ $1 * 16 ] + for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 + do mkdev pd$D$P b 45 $[ $1 * 16 + $P ] + done +} +# +cd /dev +# +for u in 0 1 2 3 ; do pd $u ; done +for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done +for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done +for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done +for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done +for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done +# +# end of mkd + +With the device files and drivers in place, you can access PARIDE devices +like any other Linux device. For example, to mount a CD-ROM in pcd0, use: + + mount /dev/pcd0 /cdrom + +If you have a fresh Avatar Shark cartridge, and the drive is pda, you +might do something like: + + fdisk /dev/pda -- make a new partition table with + partition 1 of type 83 + + mke2fs /dev/pda1 -- to build the file system + + mkdir /shark -- make a place to mount the disk + + mount /dev/pda1 /shark + +Devices like the Imation superdisk work in the same way, except that +they do not have a partition table. For example to make a 120MB +floppy that you could share with a DOS system: + + mkdosfs /dev/pf0 + mount /dev/pf0 /mnt + + +2.4 The pf driver + +The pf driver is intended for use with parallel port ATAPI disk +devices. The most common devices in this category are PD drives +and LS-120 drives. Traditionally, media for these devices are not +partitioned. Consequently, the pf driver does not support partitioned +media. This may be changed in a future version of the driver. + +2.5 Using the pt driver + +The pt driver for parallel port ATAPI tape drives is a minimal driver. +It does not yet support many of the standard tape ioctl operations. +For best performance, a block size of 32KB should be used. You will +probably want to set the parallel port delay to 0, if you can. + +2.6 Using the pg driver + +The pg driver can be used in conjunction with the cdrecord program +to create CD-ROMs. Please get cdrecord version 1.6.1 or later +from ftp://ftp.fokus.gmd.de/pub/unix/cdrecord/ . To record CD-R media +your parallel port should ideally be set to EPP mode, and the "port delay" +should be set to 0. With those settings it is possible to record at 2x +speed without any buffer underruns. If you cannot get the driver to work +in EPP mode, try to use "bidirectional" or "PS/2" mode and 1x speeds only. + + +3. Troubleshooting + +3.1 Use EPP mode if you can + +The most common problems that people report with the PARIDE drivers +concern the parallel port CMOS settings. At this time, none of the +PARIDE protocol modules support ECP mode, or any ECP combination modes. +If you are able to do so, please set your parallel port into EPP mode +using your CMOS setup procedure. + +3.2 Check the port delay + +Some parallel ports cannot reliably transfer data at full speed. To +offset the errors, the PARIDE protocol modules introduce a "port +delay" between each access to the i/o ports. Each protocol sets +a default value for this delay. In most cases, the user can override +the default and set it to 0 - resulting in somewhat higher transfer +rates. In some rare cases (especially with older 486 systems) the +default delays are not long enough. if you experience corrupt data +transfers, or unexpected failures, you may wish to increase the +port delay. The delay can be programmed using the "driveN" parameters +to each of the high-level drivers. Please see the notes above, or +read the comments at the beginning of the driver source files in +linux/drivers/block/paride. + +3.3 Some drives need a printer reset + +There appear to be a number of "noname" external drives on the market +that do not always power up correctly. We have noticed this with some +drives based on OnSpec and older Freecom adapters. In these rare cases, +the adapter can often be reinitialised by issuing a "printer reset" on +the parallel port. As the reset operation is potentially disruptive in +multiple device environments, the PARIDE drivers will not do it +automatically. You can however, force a printer reset by doing: + + insmod lp reset=1 + rmmod lp + +If you have one of these marginal cases, you should probably build +your paride drivers as modules, and arrange to do the printer reset +before loading the PARIDE drivers. + +3.4 Use the verbose option and dmesg if you need help + +While a lot of testing has gone into these drivers to make them work +as smoothly as possible, problems will arise. If you do have problems, +please check all the obvious things first: does the drive work in +DOS with the manufacturer's drivers ? If that doesn't yield any useful +clues, then please make sure that only one drive is hooked to your system, +and that either (a) PARPORT is enabled or (b) no other device driver +is using your parallel port (check in /proc/ioports). Then, load the +appropriate drivers (you can load several protocol modules if you want) +as in: + + # insmod paride + # insmod epat + # insmod bpck + # insmod kbic + ... + # insmod pd verbose=1 + +(using the correct driver for the type of device you have, of course). +The verbose=1 parameter will cause the drivers to log a trace of their +activity as they attempt to locate your drive. + +Use 'dmesg' to capture a log of all the PARIDE messages (any messages +beginning with paride:, a protocol module's name or a driver's name) and +include that with your bug report. You can submit a bug report in one +of two ways. Either send it directly to the author of the PARIDE suite, +by e-mail to grant@torque.net, or join the linux-parport mailing list +and post your report there. + +3.5 For more information or help + +You can join the linux-parport mailing list by sending a mail message +to + linux-parport-request@torque.net + +with the single word + + subscribe + +in the body of the mail message (not in the subject line). Please be +sure that your mail program is correctly set up when you do this, as +the list manager is a robot that will subscribe you using the reply +address in your mail headers. REMOVE any anti-spam gimmicks you may +have in your mail headers, when sending mail to the list server. + +You might also find some useful information on the linux-parport +web pages (although they are not always up to date) at + + http://www.torque.net/parport/ + + diff --git a/Documentation/blockdev/ramdisk.txt b/Documentation/blockdev/ramdisk.txt new file mode 100644 index 00000000000..6c820baa19a --- /dev/null +++ b/Documentation/blockdev/ramdisk.txt @@ -0,0 +1,165 @@ +Using the RAM disk block device with Linux +------------------------------------------ + +Contents: + + 1) Overview + 2) Kernel Command Line Parameters + 3) Using "rdev -r" + 4) An Example of Creating a Compressed RAM Disk + + +1) Overview +----------- + +The RAM disk driver is a way to use main system memory as a block device. It +is required for initrd, an initial filesystem used if you need to load modules +in order to access the root filesystem (see Documentation/initrd.txt). It can +also be used for a temporary filesystem for crypto work, since the contents +are erased on reboot. + +The RAM disk dynamically grows as more space is required. It does this by using +RAM from the buffer cache. The driver marks the buffers it is using as dirty +so that the VM subsystem does not try to reclaim them later. + +The RAM disk supports up to 16 RAM disks by default, and can be reconfigured +to support an unlimited number of RAM disks (at your own risk). Just change +the configuration symbol BLK_DEV_RAM_COUNT in the Block drivers config menu +and (re)build the kernel. + +To use RAM disk support with your system, run './MAKEDEV ram' from the /dev +directory. RAM disks are all major number 1, and start with minor number 0 +for /dev/ram0, etc. If used, modern kernels use /dev/ram0 for an initrd. + +The new RAM disk also has the ability to load compressed RAM disk images, +allowing one to squeeze more programs onto an average installation or +rescue floppy disk. + + +2) Kernel Command Line Parameters +--------------------------------- + + ramdisk_size=N + ============== + +This parameter tells the RAM disk driver to set up RAM disks of N k size. The +default is 4096 (4 MB) (8192 (8 MB) on S390). + + ramdisk_blocksize=N + =================== + +This parameter tells the RAM disk driver how many bytes to use per block. The +default is 1024 (BLOCK_SIZE). + + +3) Using "rdev -r" +------------------ + +The usage of the word (two bytes) that "rdev -r" sets in the kernel image is +as follows. The low 11 bits (0 -> 10) specify an offset (in 1 k blocks) of up +to 2 MB (2^11) of where to find the RAM disk (this used to be the size). Bit +14 indicates that a RAM disk is to be loaded, and bit 15 indicates whether a +prompt/wait sequence is to be given before trying to read the RAM disk. Since +the RAM disk dynamically grows as data is being written into it, a size field +is not required. Bits 11 to 13 are not currently used and may as well be zero. +These numbers are no magical secrets, as seen below: + +./arch/i386/kernel/setup.c:#define RAMDISK_IMAGE_START_MASK 0x07FF +./arch/i386/kernel/setup.c:#define RAMDISK_PROMPT_FLAG 0x8000 +./arch/i386/kernel/setup.c:#define RAMDISK_LOAD_FLAG 0x4000 + +Consider a typical two floppy disk setup, where you will have the +kernel on disk one, and have already put a RAM disk image onto disk #2. + +Hence you want to set bits 0 to 13 as 0, meaning that your RAM disk +starts at an offset of 0 kB from the beginning of the floppy. +The command line equivalent is: "ramdisk_start=0" + +You want bit 14 as one, indicating that a RAM disk is to be loaded. +The command line equivalent is: "load_ramdisk=1" + +You want bit 15 as one, indicating that you want a prompt/keypress +sequence so that you have a chance to switch floppy disks. +The command line equivalent is: "prompt_ramdisk=1" + +Putting that together gives 2^15 + 2^14 + 0 = 49152 for an rdev word. +So to create disk one of the set, you would do: + + /usr/src/linux# cat arch/i386/boot/zImage > /dev/fd0 + /usr/src/linux# rdev /dev/fd0 /dev/fd0 + /usr/src/linux# rdev -r /dev/fd0 49152 + +If you make a boot disk that has LILO, then for the above, you would use: + append = "ramdisk_start=0 load_ramdisk=1 prompt_ramdisk=1" +Since the default start = 0 and the default prompt = 1, you could use: + append = "load_ramdisk=1" + + +4) An Example of Creating a Compressed RAM Disk +---------------------------------------------- + +To create a RAM disk image, you will need a spare block device to +construct it on. This can be the RAM disk device itself, or an +unused disk partition (such as an unmounted swap partition). For this +example, we will use the RAM disk device, "/dev/ram0". + +Note: This technique should not be done on a machine with less than 8 MB +of RAM. If using a spare disk partition instead of /dev/ram0, then this +restriction does not apply. + +a) Decide on the RAM disk size that you want. Say 2 MB for this example. + Create it by writing to the RAM disk device. (This step is not currently + required, but may be in the future.) It is wise to zero out the + area (esp. for disks) so that maximal compression is achieved for + the unused blocks of the image that you are about to create. + + dd if=/dev/zero of=/dev/ram0 bs=1k count=2048 + +b) Make a filesystem on it. Say ext2fs for this example. + + mke2fs -vm0 /dev/ram0 2048 + +c) Mount it, copy the files you want to it (eg: /etc/* /dev/* ...) + and unmount it again. + +d) Compress the contents of the RAM disk. The level of compression + will be approximately 50% of the space used by the files. Unused + space on the RAM disk will compress to almost nothing. + + dd if=/dev/ram0 bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz + +e) Put the kernel onto the floppy + + dd if=zImage of=/dev/fd0 bs=1k + +f) Put the RAM disk image onto the floppy, after the kernel. Use an offset + that is slightly larger than the kernel, so that you can put another + (possibly larger) kernel onto the same floppy later without overlapping + the RAM disk image. An offset of 400 kB for kernels about 350 kB in + size would be reasonable. Make sure offset+size of ram_image.gz is + not larger than the total space on your floppy (usually 1440 kB). + + dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400 + +g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc. + For prompt_ramdisk=1, load_ramdisk=1, ramdisk_start=400, one would + have 2^15 + 2^14 + 400 = 49552. + + rdev /dev/fd0 /dev/fd0 + rdev -r /dev/fd0 49552 + +That is it. You now have your boot/root compressed RAM disk floppy. Some +users may wish to combine steps (d) and (f) by using a pipe. + +-------------------------------------------------------------------------- + Paul Gortmaker 12/95 + +Changelog: +---------- + +10-22-04 : Updated to reflect changes in command line options, remove + obsolete references, general cleanup. + James Nelson (james4765@gmail.com) + + +12-95 : Original Document |