1What: /sys/block/<disk>/stat 2Date: February 2008 3Contact: Jerome Marchand <jmarchan@redhat.com> 4Description: 5 The /sys/block/<disk>/stat files displays the I/O 6 statistics of disk <disk>. They contain 11 fields: 7 1 - reads completed successfully 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 21What: /sys/block/<disk>/<part>/stat 22Date: February 2008 23Contact: Jerome Marchand <jmarchan@redhat.com> 24Description: 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 31What: /sys/block/<disk>/integrity/format 32Date: June 2008 33Contact: Martin K. Petersen <martin.petersen@oracle.com> 34Description: 35 Metadata format for integrity capable block device. 36 E.g. T10-DIF-TYPE1-CRC. 37 38 39What: /sys/block/<disk>/integrity/read_verify 40Date: June 2008 41Contact: Martin K. Petersen <martin.petersen@oracle.com> 42Description: 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 48What: /sys/block/<disk>/integrity/tag_size 49Date: June 2008 50Contact: Martin K. Petersen <martin.petersen@oracle.com> 51Description: 52 Number of bytes of integrity tag space available per 53 512 bytes of data. 54 55 56What: /sys/block/<disk>/integrity/write_generate 57Date: June 2008 58Contact: Martin K. Petersen <martin.petersen@oracle.com> 59Description: 60 Indicates whether the block layer should automatically 61 generate checksums for write requests bound for 62 devices that support receiving integrity metadata. 63 64What: /sys/block/<disk>/alignment_offset 65Date: April 2009 66Contact: Martin K. Petersen <martin.petersen@oracle.com> 67Description: 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 75What: /sys/block/<disk>/<partition>/alignment_offset 76Date: April 2009 77Contact: Martin K. Petersen <martin.petersen@oracle.com> 78Description: 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 86What: /sys/block/<disk>/queue/logical_block_size 87Date: May 2009 88Contact: Martin K. Petersen <martin.petersen@oracle.com> 89Description: 90 This is the smallest unit the storage device can 91 address. It is typically 512 bytes. 92 93What: /sys/block/<disk>/queue/physical_block_size 94Date: May 2009 95Contact: Martin K. Petersen <martin.petersen@oracle.com> 96Description: 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 105What: /sys/block/<disk>/queue/minimum_io_size 106Date: April 2009 107Contact: Martin K. Petersen <martin.petersen@oracle.com> 108Description: 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 119What: /sys/block/<disk>/queue/optimal_io_size 120Date: April 2009 121Contact: Martin K. Petersen <martin.petersen@oracle.com> 122Description: 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. 131 132What: /sys/block/<disk>/queue/nomerges 133Date: January 2010 134Contact: 135Description: 136 Standard I/O elevator operations include attempts to 137 merge contiguous I/Os. For known random I/O loads these 138 attempts will always fail and result in extra cycles 139 being spent in the kernel. This allows one to turn off 140 this behavior on one of two ways: When set to 1, complex 141 merge checks are disabled, but the simple one-shot merges 142 with the previous I/O request are enabled. When set to 2, 143 all merge tries are disabled. The default value is 0 - 144 which enables all types of merge tries. 145