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authorNeilBrown <neilb@suse.de>2011-01-13 20:00:02 +0000
committerAlasdair G Kergon <agk@redhat.com>2011-01-13 20:00:02 +0000
commit9d09e663d5502c46f2d9481c04c1087e1c2da698 (patch)
tree993f10eb7100a6ce8c00c0cff7951d7ffea9488e /drivers/md/Kconfig
parent99d03c141b40914b67d63c9d23b8da4386422ed7 (diff)
dm: raid456 basic support
This patch is the skeleton for the DM target that will be the bridge from DM to MD (initially RAID456 and later RAID1). It provides a way to use device-mapper interfaces to the MD RAID456 drivers. As with all device-mapper targets, the nominal public interfaces are the constructor (CTR) tables and the status outputs (both STATUSTYPE_INFO and STATUSTYPE_TABLE). The CTR table looks like the following: 1: <s> <l> raid \ 2: <raid_type> <#raid_params> <raid_params> \ 3: <#raid_devs> <meta_dev1> <dev1> .. <meta_devN> <devN> Line 1 contains the standard first three arguments to any device-mapper target - the start, length, and target type fields. The target type in this case is "raid". Line 2 contains the arguments that define the particular raid type/personality/level, the required arguments for that raid type, and any optional arguments. Possible raid types include: raid4, raid5_la, raid5_ls, raid5_rs, raid6_zr, raid6_nr, and raid6_nc. (again, raid1 is planned for the future.) The list of required and optional parameters is the same for all the current raid types. The required parameters are positional, while the optional parameters are given as key/value pairs. The possible parameters are as follows: <chunk_size> Chunk size in sectors. [[no]sync] Force/Prevent RAID initialization [rebuild <idx>] Rebuild the drive indicated by the index [daemon_sleep <ms>] Time between bitmap daemon work to clear bits [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization [max_write_behind <value>] See '-write-behind=' (man mdadm) [stripe_cache <sectors>] Stripe cache size for higher RAIDs Line 3 contains the list of devices that compose the array in metadata/data device pairs. If the metadata is stored separately, a '-' is given for the metadata device position. If a drive has failed or is missing at creation time, a '-' can be given for both the metadata and data drives for a given position. Examples: # RAID4 - 4 data drives, 1 parity # No metadata devices specified to hold superblock/bitmap info # Chunk size of 1MiB # (Lines separated for easy reading) 0 1960893648 raid \ raid4 1 2048 \ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 # RAID4 - 4 data drives, 1 parity (no metadata devices) # Chunk size of 1MiB, force RAID initialization, # min recovery rate at 20 kiB/sec/disk 0 1960893648 raid \ raid4 4 2048 min_recovery_rate 20 sync\ 5 - 8:17 - 8:33 - 8:49 - 8:65 - 8:81 Performing a 'dmsetup table' should display the CTR table used to construct the mapping (with possible reordering of optional parameters). Performing a 'dmsetup status' will yield information on the state and health of the array. The output is as follows: 1: <s> <l> raid \ 2: <raid_type> <#devices> <1 health char for each dev> <resync_ratio> Line 1 is standard DM output. Line 2 is best shown by example: 0 1960893648 raid raid4 5 AAAAA 2/490221568 Here we can see the RAID type is raid4, there are 5 devices - all of which are 'A'live, and the array is 2/490221568 complete with recovery. Cc: linux-raid@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/Kconfig')
-rw-r--r--drivers/md/Kconfig24
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index bf1a95e3155..98d9ec85e0e 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -240,6 +240,30 @@ config DM_MIRROR
Allow volume managers to mirror logical volumes, also
needed for live data migration tools such as 'pvmove'.
+config DM_RAID
+ tristate "RAID 4/5/6 target (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ select MD_RAID456
+ select BLK_DEV_MD
+ ---help---
+ A dm target that supports RAID4, RAID5 and RAID6 mappings
+
+ A RAID-5 set of N drives with a capacity of C MB per drive provides
+ the capacity of C * (N - 1) MB, and protects against a failure
+ of a single drive. For a given sector (row) number, (N - 1) drives
+ contain data sectors, and one drive contains the parity protection.
+ For a RAID-4 set, the parity blocks are present on a single drive,
+ while a RAID-5 set distributes the parity across the drives in one
+ of the available parity distribution methods.
+
+ A RAID-6 set of N drives with a capacity of C MB per drive
+ provides the capacity of C * (N - 2) MB, and protects
+ against a failure of any two drives. For a given sector
+ (row) number, (N - 2) drives contain data sectors, and two
+ drives contains two independent redundancy syndromes. Like
+ RAID-5, RAID-6 distributes the syndromes across the drives
+ in one of the available parity distribution methods.
+
config DM_LOG_USERSPACE
tristate "Mirror userspace logging (EXPERIMENTAL)"
depends on DM_MIRROR && EXPERIMENTAL && NET