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 a physical storage device can
  98                 write atomically.  It is usually the same as the logical
  99                 block size but may be bigger.  One example is SATA
 100                 drives with 4KB sectors that expose a 512-byte logical
 101                 block size to the operating system.  For stacked block
 102                 devices the physical_block_size variable contains the
 103                 maximum physical_block_size of the component devices.
 104
 105 What:           /sys/block/<disk>/queue/minimum_io_size
 106 Date:           April 2009
 107 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
 108 Description:
 109                 Storage devices may report a granularity or preferred
 110                 minimum I/O size which is the smallest request the
 111                 device can perform without incurring a performance
 112                 penalty.  For disk drives this is often the physical
 113                 block size.  For RAID arrays it is often the stripe
 114                 chunk size.  A properly aligned multiple of
 115                 minimum_io_size is the preferred request size for
 116                 workloads where a high number of I/O operations is
 117                 desired.
 118
 119 What:           /sys/block/<disk>/queue/optimal_io_size
 120 Date:           April 2009
 121 Contact:        Martin K. Petersen <martin.petersen@oracle.com>
 122 Description:
 123                 Storage devices may report an optimal I/O size, which is
 124                 the device's preferred unit for sustained I/O.  This is
 125                 rarely reported for disk drives.  For RAID arrays it is
 126                 usually the stripe width or the internal track size.  A
 127                 properly aligned multiple of optimal_io_size is the
 128                 preferred request size for workloads where sustained
 129                 throughput is desired.  If no optimal I/O size is
 130                 reported this file contains 0.