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Diffstat (limited to 'Documentation/ABI/testing/sysfs-block')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index 44f52a4f590..5f3bedaf8e3 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block @@ -60,3 +60,71 @@ Description: Indicates whether the block layer should automatically generate checksums for write requests bound for devices that support receiving integrity metadata. + +What: /sys/block/<disk>/alignment_offset +Date: April 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + Storage devices may report a physical block size that is + bigger than the logical block size (for instance a drive + with 4KB physical sectors exposing 512-byte logical + blocks to the operating system). This parameter + indicates how many bytes the beginning of the device is + offset from the disk's natural alignment. + +What: /sys/block/<disk>/<partition>/alignment_offset +Date: April 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + Storage devices may report a physical block size that is + bigger than the logical block size (for instance a drive + with 4KB physical sectors exposing 512-byte logical + blocks to the operating system). This parameter + indicates how many bytes the beginning of the partition + is offset from the disk's natural alignment. + +What: /sys/block/<disk>/queue/logical_block_size +Date: May 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + This is the smallest unit the storage device can + address. It is typically 512 bytes. + +What: /sys/block/<disk>/queue/physical_block_size +Date: May 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + This is the smallest unit a physical storage device can + write atomically. It is usually the same as the logical + block size but may be bigger. One example is SATA + drives with 4KB sectors that expose a 512-byte logical + block size to the operating system. For stacked block + devices the physical_block_size variable contains the + maximum physical_block_size of the component devices. + +What: /sys/block/<disk>/queue/minimum_io_size +Date: April 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + Storage devices may report a granularity or preferred + minimum I/O size which is the smallest request the + device can perform without incurring a performance + penalty. For disk drives this is often the physical + block size. For RAID arrays it is often the stripe + chunk size. A properly aligned multiple of + minimum_io_size is the preferred request size for + workloads where a high number of I/O operations is + desired. + +What: /sys/block/<disk>/queue/optimal_io_size +Date: April 2009 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + Storage devices may report an optimal I/O size, which is + the device's preferred unit for sustained I/O. This is + rarely reported for disk drives. For RAID arrays it is + usually the stripe width or the internal track size. A + properly aligned multiple of optimal_io_size is the + preferred request size for workloads where sustained + throughput is desired. If no optimal I/O size is + reported this file contains 0. |