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Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index 44f52a4f5903..cbbd3e069945 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block | |||
| @@ -60,3 +60,62 @@ Description: | |||
| 60 | Indicates whether the block layer should automatically | 60 | Indicates whether the block layer should automatically |
| 61 | generate checksums for write requests bound for | 61 | generate checksums for write requests bound for |
| 62 | devices that support receiving integrity metadata. | 62 | devices that support receiving integrity metadata. |
| 63 | |||
| 64 | What: /sys/block/<disk>/alignment_offset | ||
| 65 | Date: April 2009 | ||
| 66 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 67 | Description: | ||
| 68 | Storage devices may report a physical block size that is | ||
| 69 | bigger than the logical block size (for instance a drive | ||
| 70 | with 4KB physical sectors exposing 512-byte logical | ||
| 71 | blocks to the operating system). This parameter | ||
| 72 | indicates how many bytes the beginning of the device is | ||
| 73 | offset from the disk's natural alignment. | ||
| 74 | |||
| 75 | What: /sys/block/<disk>/<partition>/alignment_offset | ||
| 76 | Date: April 2009 | ||
| 77 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 78 | Description: | ||
| 79 | Storage devices may report a physical block size that is | ||
| 80 | bigger than the logical block size (for instance a drive | ||
| 81 | with 4KB physical sectors exposing 512-byte logical | ||
| 82 | blocks to the operating system). This parameter | ||
| 83 | indicates how many bytes the beginning of the partition | ||
| 84 | is offset from the disk's natural alignment. | ||
| 85 | |||
| 86 | What: /sys/block/<disk>/queue/logical_block_size | ||
| 87 | Date: May 2009 | ||
| 88 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 89 | Description: | ||
| 90 | This is the smallest unit the storage device can | ||
| 91 | address. It is typically 512 bytes. | ||
| 92 | |||
| 93 | What: /sys/block/<disk>/queue/physical_block_size | ||
| 94 | Date: May 2009 | ||
| 95 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 96 | Description: | ||
| 97 | This is the smallest unit the storage device can write | ||
| 98 | without resorting to read-modify-write operation. It is | ||
| 99 | usually the same as the logical block size but may be | ||
| 100 | bigger. One example is SATA drives with 4KB sectors | ||
| 101 | that expose a 512-byte logical block size to the | ||
| 102 | operating system. | ||
| 103 | |||
| 104 | What: /sys/block/<disk>/queue/minimum_io_size | ||
| 105 | Date: April 2009 | ||
| 106 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 107 | Description: | ||
| 108 | Storage devices may report a preferred minimum I/O size, | ||
| 109 | which is the smallest request the device can perform | ||
| 110 | without incurring a read-modify-write penalty. For disk | ||
| 111 | drives this is often the physical block size. For RAID | ||
| 112 | arrays it is often the stripe chunk size. | ||
| 113 | |||
| 114 | What: /sys/block/<disk>/queue/optimal_io_size | ||
| 115 | Date: April 2009 | ||
| 116 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | ||
| 117 | Description: | ||
| 118 | Storage devices may report an optimal I/O size, which is | ||
| 119 | the device's preferred unit of receiving I/O. This is | ||
| 120 | rarely reported for disk drives. For RAID devices it is | ||
| 121 | usually the stripe width or the internal block size. | ||