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/device_is_integrity_capable 57Date: July 2014 58Contact: Martin K. Petersen <martin.petersen@oracle.com> 59Description: 60 Indicates whether a storage device is capable of storing 61 integrity metadata. Set if the device is T10 PI-capable. 62 63What: /sys/block/<disk>/integrity/protection_interval_bytes 64Date: July 2015 65Contact: Martin K. Petersen <martin.petersen@oracle.com> 66Description: 67 Describes the number of data bytes which are protected 68 by one integrity tuple. Typically the device's logical 69 block size. 70 71What: /sys/block/<disk>/integrity/write_generate 72Date: June 2008 73Contact: Martin K. Petersen <martin.petersen@oracle.com> 74Description: 75 Indicates whether the block layer should automatically 76 generate checksums for write requests bound for 77 devices that support receiving integrity metadata. 78 79What: /sys/block/<disk>/alignment_offset 80Date: April 2009 81Contact: Martin K. Petersen <martin.petersen@oracle.com> 82Description: 83 Storage devices may report a physical block size that is 84 bigger than the logical block size (for instance a drive 85 with 4KB physical sectors exposing 512-byte logical 86 blocks to the operating system). This parameter 87 indicates how many bytes the beginning of the device is 88 offset from the disk's natural alignment. 89 90What: /sys/block/<disk>/<partition>/alignment_offset 91Date: April 2009 92Contact: Martin K. Petersen <martin.petersen@oracle.com> 93Description: 94 Storage devices may report a physical block size that is 95 bigger than the logical block size (for instance a drive 96 with 4KB physical sectors exposing 512-byte logical 97 blocks to the operating system). This parameter 98 indicates how many bytes the beginning of the partition 99 is offset from the disk's natural alignment. 100 101What: /sys/block/<disk>/queue/logical_block_size 102Date: May 2009 103Contact: Martin K. Petersen <martin.petersen@oracle.com> 104Description: 105 This is the smallest unit the storage device can 106 address. It is typically 512 bytes. 107 108What: /sys/block/<disk>/queue/physical_block_size 109Date: May 2009 110Contact: Martin K. Petersen <martin.petersen@oracle.com> 111Description: 112 This is the smallest unit a physical storage device can 113 write atomically. It is usually the same as the logical 114 block size but may be bigger. One example is SATA 115 drives with 4KB sectors that expose a 512-byte logical 116 block size to the operating system. For stacked block 117 devices the physical_block_size variable contains the 118 maximum physical_block_size of the component devices. 119 120What: /sys/block/<disk>/queue/minimum_io_size 121Date: April 2009 122Contact: Martin K. Petersen <martin.petersen@oracle.com> 123Description: 124 Storage devices may report a granularity or preferred 125 minimum I/O size which is the smallest request the 126 device can perform without incurring a performance 127 penalty. For disk drives this is often the physical 128 block size. For RAID arrays it is often the stripe 129 chunk size. A properly aligned multiple of 130 minimum_io_size is the preferred request size for 131 workloads where a high number of I/O operations is 132 desired. 133 134What: /sys/block/<disk>/queue/optimal_io_size 135Date: April 2009 136Contact: Martin K. Petersen <martin.petersen@oracle.com> 137Description: 138 Storage devices may report an optimal I/O size, which is 139 the device's preferred unit for sustained I/O. This is 140 rarely reported for disk drives. For RAID arrays it is 141 usually the stripe width or the internal track size. A 142 properly aligned multiple of optimal_io_size is the 143 preferred request size for workloads where sustained 144 throughput is desired. If no optimal I/O size is 145 reported this file contains 0. 146 147What: /sys/block/<disk>/queue/nomerges 148Date: January 2010 149Contact: 150Description: 151 Standard I/O elevator operations include attempts to 152 merge contiguous I/Os. For known random I/O loads these 153 attempts will always fail and result in extra cycles 154 being spent in the kernel. This allows one to turn off 155 this behavior on one of two ways: When set to 1, complex 156 merge checks are disabled, but the simple one-shot merges 157 with the previous I/O request are enabled. When set to 2, 158 all merge tries are disabled. The default value is 0 - 159 which enables all types of merge tries. 160 161What: /sys/block/<disk>/discard_alignment 162Date: May 2011 163Contact: Martin K. Petersen <martin.petersen@oracle.com> 164Description: 165 Devices that support discard functionality may 166 internally allocate space in units that are bigger than 167 the exported logical block size. The discard_alignment 168 parameter indicates how many bytes the beginning of the 169 device is offset from the internal allocation unit's 170 natural alignment. 171 172What: /sys/block/<disk>/<partition>/discard_alignment 173Date: May 2011 174Contact: Martin K. Petersen <martin.petersen@oracle.com> 175Description: 176 Devices that support discard functionality may 177 internally allocate space in units that are bigger than 178 the exported logical block size. The discard_alignment 179 parameter indicates how many bytes the beginning of the 180 partition is offset from the internal allocation unit's 181 natural alignment. 182 183What: /sys/block/<disk>/queue/discard_granularity 184Date: May 2011 185Contact: Martin K. Petersen <martin.petersen@oracle.com> 186Description: 187 Devices that support discard functionality may 188 internally allocate space using units that are bigger 189 than the logical block size. The discard_granularity 190 parameter indicates the size of the internal allocation 191 unit in bytes if reported by the device. Otherwise the 192 discard_granularity will be set to match the device's 193 physical block size. A discard_granularity of 0 means 194 that the device does not support discard functionality. 195 196What: /sys/block/<disk>/queue/discard_max_bytes 197Date: May 2011 198Contact: Martin K. Petersen <martin.petersen@oracle.com> 199Description: 200 Devices that support discard functionality may have 201 internal limits on the number of bytes that can be 202 trimmed or unmapped in a single operation. Some storage 203 protocols also have inherent limits on the number of 204 blocks that can be described in a single command. The 205 discard_max_bytes parameter is set by the device driver 206 to the maximum number of bytes that can be discarded in 207 a single operation. Discard requests issued to the 208 device must not exceed this limit. A discard_max_bytes 209 value of 0 means that the device does not support 210 discard functionality. 211 212What: /sys/block/<disk>/queue/discard_zeroes_data 213Date: May 2011 214Contact: Martin K. Petersen <martin.petersen@oracle.com> 215Description: 216 Will always return 0. Don't rely on any specific behavior 217 for discards, and don't read this file. 218 219What: /sys/block/<disk>/queue/write_same_max_bytes 220Date: January 2012 221Contact: Martin K. Petersen <martin.petersen@oracle.com> 222Description: 223 Some devices support a write same operation in which a 224 single data block can be written to a range of several 225 contiguous blocks on storage. This can be used to wipe 226 areas on disk or to initialize drives in a RAID 227 configuration. write_same_max_bytes indicates how many 228 bytes can be written in a single write same command. If 229 write_same_max_bytes is 0, write same is not supported 230 by the device. 231 232What: /sys/block/<disk>/queue/write_zeroes_max_bytes 233Date: November 2016 234Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> 235Description: 236 Devices that support write zeroes operation in which a 237 single request can be issued to zero out the range of 238 contiguous blocks on storage without having any payload 239 in the request. This can be used to optimize writing zeroes 240 to the devices. write_zeroes_max_bytes indicates how many 241 bytes can be written in a single write zeroes command. If 242 write_zeroes_max_bytes is 0, write zeroes is not supported 243 by the device. 244 245What: /sys/block/<disk>/queue/zoned 246Date: September 2016 247Contact: Damien Le Moal <damien.lemoal@hgst.com> 248Description: 249 zoned indicates if the device is a zoned block device 250 and the zone model of the device if it is indeed zoned. 251 The possible values indicated by zoned are "none" for 252 regular block devices and "host-aware" or "host-managed" 253 for zoned block devices. The characteristics of 254 host-aware and host-managed zoned block devices are 255 described in the ZBC (Zoned Block Commands) and ZAC 256 (Zoned Device ATA Command Set) standards. These standards 257 also define the "drive-managed" zone model. However, 258 since drive-managed zoned block devices do not support 259 zone commands, they will be treated as regular block 260 devices and zoned will report "none". 261 262What: /sys/block/<disk>/queue/chunk_sectors 263Date: September 2016 264Contact: Hannes Reinecke <hare@suse.com> 265Description: 266 chunk_sectors has different meaning depending on the type 267 of the disk. For a RAID device (dm-raid), chunk_sectors 268 indicates the size in 512B sectors of the RAID volume 269 stripe segment. For a zoned block device, either 270 host-aware or host-managed, chunk_sectors indicates the 271 size of 512B sectors of the zones of the device, with 272 the eventual exception of the last zone of the device 273 which may be smaller. 274
