Documentation/ABI/testing/sysfs-block

   1 What:           /sys/block/<disk>/stat
   2 Date:           February 2008
   3 Contact:        Jerome Marchand <jmarchan@redhat.com>
   4 Description:
   5                 The /sys/block/<disk>/stat files displays the I/O
   6                 statistics of disk <disk>. They contain 11 fields:
   7                  1 - reads completed succesfully
   8                  2 - reads merged
   9                  3 - sectors read
  10                  4 - time spent reading (ms)
  11                  5 - writes completed
  12                  6 - writes merged
  13                  7 - sectors written
  14                  8 - time spent writing (ms)
  15                  9 - I/Os currently in progress
  16                 10 - time spent doing I/Os (ms)
  17                 11 - weighted time spent doing I/Os (ms)
  18                 For more details refer Documentation/iostats.txt
  19
  20
  21 What:           /sys/block/<disk>/<part>/stat
  22 Date:           February 2008
  23 Contact:        Jerome Marchand <jmarchan@redhat.com>
  24 Description:
  25                 The /sys/block/<disk>/<part>/stat files display the
  26                 I/O statistics of partition <part>. The format is the
  27                 same as the above-written /sys/block/<disk>/stat
  28                 format.
  29
  30
  31 What:           /sys/block/<disk>/integrity/format
  32 Date:           June 2008
  33 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
  34 Description:
  35                 Metadata format for integrity capable block device.
  36                 E.g. T10-DIF-TYPE1-CRC.
  37
  38
  39 What:           /sys/block/<disk>/integrity/read_verify
  40 Date:           June 2008
  41 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
  42 Description:
  43                 Indicates whether the block layer should verify the
  44                 integrity of read requests serviced by devices that
  45                 support sending integrity metadata.
  46
  47
  48 What:           /sys/block/<disk>/integrity/tag_size
  49 Date:           June 2008
  50 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
  51 Description:
  52                 Number of bytes of integrity tag space available per
  53                 512 bytes of data.
  54
  55
  56 What:           /sys/block/<disk>/integrity/write_generate
  57 Date:           June 2008
  58 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
  59 Description:
  60                 Indicates whether the block layer should automatically
  61                 generate checksums for write requests bound for
  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.