1What: /sys/block/<disk>/alignment_offset 2Date: April 2009 3Contact: Martin K. Petersen <martin.petersen@oracle.com> 4Description: 5 Storage devices may report a physical block size that is 6 bigger than the logical block size (for instance a drive 7 with 4KB physical sectors exposing 512-byte logical 8 blocks to the operating system). This parameter 9 indicates how many bytes the beginning of the device is 10 offset from the disk's natural alignment. 11 12 13What: /sys/block/<disk>/discard_alignment 14Date: May 2011 15Contact: Martin K. Petersen <martin.petersen@oracle.com> 16Description: 17 Devices that support discard functionality may 18 internally allocate space in units that are bigger than 19 the exported logical block size. The discard_alignment 20 parameter indicates how many bytes the beginning of the 21 device is offset from the internal allocation unit's 22 natural alignment. 23 24 25What: /sys/block/<disk>/diskseq 26Date: February 2021 27Contact: Matteo Croce <mcroce@microsoft.com> 28Description: 29 The /sys/block/<disk>/diskseq files reports the disk 30 sequence number, which is a monotonically increasing 31 number assigned to every drive. 32 Some devices, like the loop device, refresh such number 33 every time the backing file is changed. 34 The value type is 64 bit unsigned. 35 36 37What: /sys/block/<disk>/inflight 38Date: October 2009 39Contact: Jens Axboe <axboe@kernel.dk>, Nikanth Karthikesan <knikanth@suse.de> 40Description: 41 Reports the number of I/O requests currently in progress 42 (pending / in flight) in a device driver. This can be less 43 than the number of requests queued in the block device queue. 44 The report contains 2 fields: one for read requests 45 and one for write requests. 46 The value type is unsigned int. 47 Cf. Documentation/block/stat.rst which contains a single value for 48 requests in flight. 49 This is related to /sys/block/<disk>/queue/nr_requests 50 and for SCSI device also its queue_depth. 51 52 53What: /sys/block/<disk>/integrity/device_is_integrity_capable 54Date: July 2014 55Contact: Martin K. Petersen <martin.petersen@oracle.com> 56Description: 57 Indicates whether a storage device is capable of storing 58 integrity metadata. Set if the device is T10 PI-capable. 59 60 61What: /sys/block/<disk>/integrity/format 62Date: June 2008 63Contact: Martin K. Petersen <martin.petersen@oracle.com> 64Description: 65 Metadata format for integrity capable block device. 66 E.g. T10-DIF-TYPE1-CRC. 67 68 69What: /sys/block/<disk>/integrity/protection_interval_bytes 70Date: July 2015 71Contact: Martin K. Petersen <martin.petersen@oracle.com> 72Description: 73 Describes the number of data bytes which are protected 74 by one integrity tuple. Typically the device's logical 75 block size. 76 77 78What: /sys/block/<disk>/integrity/read_verify 79Date: June 2008 80Contact: Martin K. Petersen <martin.petersen@oracle.com> 81Description: 82 Indicates whether the block layer should verify the 83 integrity of read requests serviced by devices that 84 support sending integrity metadata. 85 86 87What: /sys/block/<disk>/integrity/tag_size 88Date: June 2008 89Contact: Martin K. Petersen <martin.petersen@oracle.com> 90Description: 91 Number of bytes of integrity tag space available per 92 512 bytes of data. 93 94 95What: /sys/block/<disk>/integrity/write_generate 96Date: June 2008 97Contact: Martin K. Petersen <martin.petersen@oracle.com> 98Description: 99 Indicates whether the block layer should automatically 100 generate checksums for write requests bound for 101 devices that support receiving integrity metadata. 102 103 104What: /sys/block/<disk>/<partition>/alignment_offset 105Date: April 2009 106Contact: Martin K. Petersen <martin.petersen@oracle.com> 107Description: 108 Storage devices may report a physical block size that is 109 bigger than the logical block size (for instance a drive 110 with 4KB physical sectors exposing 512-byte logical 111 blocks to the operating system). This parameter 112 indicates how many bytes the beginning of the partition 113 is offset from the disk's natural alignment. 114 115 116What: /sys/block/<disk>/<partition>/discard_alignment 117Date: May 2011 118Contact: Martin K. Petersen <martin.petersen@oracle.com> 119Description: 120 Devices that support discard functionality may 121 internally allocate space in units that are bigger than 122 the exported logical block size. The discard_alignment 123 parameter indicates how many bytes the beginning of the 124 partition is offset from the internal allocation unit's 125 natural alignment. 126 127 128What: /sys/block/<disk>/<partition>/stat 129Date: February 2008 130Contact: Jerome Marchand <jmarchan@redhat.com> 131Description: 132 The /sys/block/<disk>/<partition>/stat files display the 133 I/O statistics of partition <partition>. The format is the 134 same as the format of /sys/block/<disk>/stat. 135 136 137What: /sys/block/<disk>/queue/add_random 138Date: June 2010 139Contact: linux-block@vger.kernel.org 140Description: 141 [RW] This file allows to turn off the disk entropy contribution. 142 Default value of this file is '1'(on). 143 144 145What: /sys/block/<disk>/queue/chunk_sectors 146Date: September 2016 147Contact: Hannes Reinecke <hare@suse.com> 148Description: 149 [RO] chunk_sectors has different meaning depending on the type 150 of the disk. For a RAID device (dm-raid), chunk_sectors 151 indicates the size in 512B sectors of the RAID volume stripe 152 segment. For a zoned block device, either host-aware or 153 host-managed, chunk_sectors indicates the size in 512B sectors 154 of the zones of the device, with the eventual exception of the 155 last zone of the device which may be smaller. 156 157 158What: /sys/block/<disk>/queue/crypto/ 159Date: February 2022 160Contact: linux-block@vger.kernel.org 161Description: 162 The presence of this subdirectory of /sys/block/<disk>/queue/ 163 indicates that the device supports inline encryption. This 164 subdirectory contains files which describe the inline encryption 165 capabilities of the device. For more information about inline 166 encryption, refer to Documentation/block/inline-encryption.rst. 167 168 169What: /sys/block/<disk>/queue/crypto/max_dun_bits 170Date: February 2022 171Contact: linux-block@vger.kernel.org 172Description: 173 [RO] This file shows the maximum length, in bits, of data unit 174 numbers accepted by the device in inline encryption requests. 175 176 177What: /sys/block/<disk>/queue/crypto/modes/<mode> 178Date: February 2022 179Contact: linux-block@vger.kernel.org 180Description: 181 [RO] For each crypto mode (i.e., encryption/decryption 182 algorithm) the device supports with inline encryption, a file 183 will exist at this location. It will contain a hexadecimal 184 number that is a bitmask of the supported data unit sizes, in 185 bytes, for that crypto mode. 186 187 Currently, the crypto modes that may be supported are: 188 189 * AES-256-XTS 190 * AES-128-CBC-ESSIV 191 * Adiantum 192 193 For example, if a device supports AES-256-XTS inline encryption 194 with data unit sizes of 512 and 4096 bytes, the file 195 /sys/block/<disk>/queue/crypto/modes/AES-256-XTS will exist and 196 will contain "0x1200". 197 198 199What: /sys/block/<disk>/queue/crypto/num_keyslots 200Date: February 2022 201Contact: linux-block@vger.kernel.org 202Description: 203 [RO] This file shows the number of keyslots the device has for 204 use with inline encryption. 205 206 207What: /sys/block/<disk>/queue/dax 208Date: June 2016 209Contact: linux-block@vger.kernel.org 210Description: 211 [RO] This file indicates whether the device supports Direct 212 Access (DAX), used by CPU-addressable storage to bypass the 213 pagecache. It shows '1' if true, '0' if not. 214 215 216What: /sys/block/<disk>/queue/discard_granularity 217Date: May 2011 218Contact: Martin K. Petersen <martin.petersen@oracle.com> 219Description: 220 [RO] Devices that support discard functionality may internally 221 allocate space using units that are bigger than the logical 222 block size. The discard_granularity parameter indicates the size 223 of the internal allocation unit in bytes if reported by the 224 device. Otherwise the discard_granularity will be set to match 225 the device's physical block size. A discard_granularity of 0 226 means that the device does not support discard functionality. 227 228 229What: /sys/block/<disk>/queue/discard_max_bytes 230Date: May 2011 231Contact: Martin K. Petersen <martin.petersen@oracle.com> 232Description: 233 [RW] While discard_max_hw_bytes is the hardware limit for the 234 device, this setting is the software limit. Some devices exhibit 235 large latencies when large discards are issued, setting this 236 value lower will make Linux issue smaller discards and 237 potentially help reduce latencies induced by large discard 238 operations. 239 240 241What: /sys/block/<disk>/queue/discard_max_hw_bytes 242Date: July 2015 243Contact: linux-block@vger.kernel.org 244Description: 245 [RO] Devices that support discard functionality may have 246 internal limits on the number of bytes that can be trimmed or 247 unmapped in a single operation. The `discard_max_hw_bytes` 248 parameter is set by the device driver to the maximum number of 249 bytes that can be discarded in a single operation. Discard 250 requests issued to the device must not exceed this limit. A 251 `discard_max_hw_bytes` value of 0 means that the device does not 252 support discard functionality. 253 254 255What: /sys/block/<disk>/queue/discard_zeroes_data 256Date: May 2011 257Contact: Martin K. Petersen <martin.petersen@oracle.com> 258Description: 259 [RO] Will always return 0. Don't rely on any specific behavior 260 for discards, and don't read this file. 261 262 263What: /sys/block/<disk>/queue/dma_alignment 264Date: May 2022 265Contact: linux-block@vger.kernel.org 266Description: 267 Reports the alignment that user space addresses must have to be 268 used for raw block device access with O_DIRECT and other driver 269 specific passthrough mechanisms. 270 271 272What: /sys/block/<disk>/queue/fua 273Date: May 2018 274Contact: linux-block@vger.kernel.org 275Description: 276 [RO] Whether or not the block driver supports the FUA flag for 277 write requests. FUA stands for Force Unit Access. If the FUA 278 flag is set that means that write requests must bypass the 279 volatile cache of the storage device. 280 281 282What: /sys/block/<disk>/queue/hw_sector_size 283Date: January 2008 284Contact: linux-block@vger.kernel.org 285Description: 286 [RO] This is the hardware sector size of the device, in bytes. 287 288 289What: /sys/block/<disk>/queue/independent_access_ranges/ 290Date: October 2021 291Contact: linux-block@vger.kernel.org 292Description: 293 [RO] The presence of this sub-directory of the 294 /sys/block/xxx/queue/ directory indicates that the device is 295 capable of executing requests targeting different sector ranges 296 in parallel. For instance, single LUN multi-actuator hard-disks 297 will have an independent_access_ranges directory if the device 298 correctly advertizes the sector ranges of its actuators. 299 300 The independent_access_ranges directory contains one directory 301 per access range, with each range described using the sector 302 (RO) attribute file to indicate the first sector of the range 303 and the nr_sectors (RO) attribute file to indicate the total 304 number of sectors in the range starting from the first sector of 305 the range. For example, a dual-actuator hard-disk will have the 306 following independent_access_ranges entries.:: 307 308 $ tree /sys/block/<disk>/queue/independent_access_ranges/ 309 /sys/block/<disk>/queue/independent_access_ranges/ 310 |-- 0 311 | |-- nr_sectors 312 | `-- sector 313 `-- 1 314 |-- nr_sectors 315 `-- sector 316 317 The sector and nr_sectors attributes use 512B sector unit, 318 regardless of the actual block size of the device. Independent 319 access ranges do not overlap and include all sectors within the 320 device capacity. The access ranges are numbered in increasing 321 order of the range start sector, that is, the sector attribute 322 of range 0 always has the value 0. 323 324 325What: /sys/block/<disk>/queue/io_poll 326Date: November 2015 327Contact: linux-block@vger.kernel.org 328Description: 329 [RW] When read, this file shows whether polling is enabled (1) 330 or disabled (0). Writing '0' to this file will disable polling 331 for this device. Writing any non-zero value will enable this 332 feature. 333 334 335What: /sys/block/<disk>/queue/io_poll_delay 336Date: November 2016 337Contact: linux-block@vger.kernel.org 338Description: 339 [RW] If polling is enabled, this controls what kind of polling 340 will be performed. It defaults to -1, which is classic polling. 341 In this mode, the CPU will repeatedly ask for completions 342 without giving up any time. If set to 0, a hybrid polling mode 343 is used, where the kernel will attempt to make an educated guess 344 at when the IO will complete. Based on this guess, the kernel 345 will put the process issuing IO to sleep for an amount of time, 346 before entering a classic poll loop. This mode might be a little 347 slower than pure classic polling, but it will be more efficient. 348 If set to a value larger than 0, the kernel will put the process 349 issuing IO to sleep for this amount of microseconds before 350 entering classic polling. 351 352 353What: /sys/block/<disk>/queue/io_timeout 354Date: November 2018 355Contact: Weiping Zhang <zhangweiping@didiglobal.com> 356Description: 357 [RW] io_timeout is the request timeout in milliseconds. If a 358 request does not complete in this time then the block driver 359 timeout handler is invoked. That timeout handler can decide to 360 retry the request, to fail it or to start a device recovery 361 strategy. 362 363 364What: /sys/block/<disk>/queue/iostats 365Date: January 2009 366Contact: linux-block@vger.kernel.org 367Description: 368 [RW] This file is used to control (on/off) the iostats 369 accounting of the disk. 370 371 372What: /sys/block/<disk>/queue/logical_block_size 373Date: May 2009 374Contact: Martin K. Petersen <martin.petersen@oracle.com> 375Description: 376 [RO] This is the smallest unit the storage device can address. 377 It is typically 512 bytes. 378 379 380What: /sys/block/<disk>/queue/max_active_zones 381Date: July 2020 382Contact: Niklas Cassel <niklas.cassel@wdc.com> 383Description: 384 [RO] For zoned block devices (zoned attribute indicating 385 "host-managed" or "host-aware"), the sum of zones belonging to 386 any of the zone states: EXPLICIT OPEN, IMPLICIT OPEN or CLOSED, 387 is limited by this value. If this value is 0, there is no limit. 388 389 If the host attempts to exceed this limit, the driver should 390 report this error with BLK_STS_ZONE_ACTIVE_RESOURCE, which user 391 space may see as the EOVERFLOW errno. 392 393 394What: /sys/block/<disk>/queue/max_discard_segments 395Date: February 2017 396Contact: linux-block@vger.kernel.org 397Description: 398 [RO] The maximum number of DMA scatter/gather entries in a 399 discard request. 400 401 402What: /sys/block/<disk>/queue/max_hw_sectors_kb 403Date: September 2004 404Contact: linux-block@vger.kernel.org 405Description: 406 [RO] This is the maximum number of kilobytes supported in a 407 single data transfer. 408 409 410What: /sys/block/<disk>/queue/max_integrity_segments 411Date: September 2010 412Contact: linux-block@vger.kernel.org 413Description: 414 [RO] Maximum number of elements in a DMA scatter/gather list 415 with integrity data that will be submitted by the block layer 416 core to the associated block driver. 417 418 419What: /sys/block/<disk>/queue/max_open_zones 420Date: July 2020 421Contact: Niklas Cassel <niklas.cassel@wdc.com> 422Description: 423 [RO] For zoned block devices (zoned attribute indicating 424 "host-managed" or "host-aware"), the sum of zones belonging to 425 any of the zone states: EXPLICIT OPEN or IMPLICIT OPEN, is 426 limited by this value. If this value is 0, there is no limit. 427 428 429What: /sys/block/<disk>/queue/max_sectors_kb 430Date: September 2004 431Contact: linux-block@vger.kernel.org 432Description: 433 [RW] This is the maximum number of kilobytes that the block 434 layer will allow for a filesystem request. Must be smaller than 435 or equal to the maximum size allowed by the hardware. 436 437 438What: /sys/block/<disk>/queue/max_segment_size 439Date: March 2010 440Contact: linux-block@vger.kernel.org 441Description: 442 [RO] Maximum size in bytes of a single element in a DMA 443 scatter/gather list. 444 445 446What: /sys/block/<disk>/queue/max_segments 447Date: March 2010 448Contact: linux-block@vger.kernel.org 449Description: 450 [RO] Maximum number of elements in a DMA scatter/gather list 451 that is submitted to the associated block driver. 452 453 454What: /sys/block/<disk>/queue/minimum_io_size 455Date: April 2009 456Contact: Martin K. Petersen <martin.petersen@oracle.com> 457Description: 458 [RO] Storage devices may report a granularity or preferred 459 minimum I/O size which is the smallest request the device can 460 perform without incurring a performance penalty. For disk 461 drives this is often the physical block size. For RAID arrays 462 it is often the stripe chunk size. A properly aligned multiple 463 of minimum_io_size is the preferred request size for workloads 464 where a high number of I/O operations is desired. 465 466 467What: /sys/block/<disk>/queue/nomerges 468Date: January 2010 469Contact: linux-block@vger.kernel.org 470Description: 471 [RW] Standard I/O elevator operations include attempts to merge 472 contiguous I/Os. For known random I/O loads these attempts will 473 always fail and result in extra cycles being spent in the 474 kernel. This allows one to turn off this behavior on one of two 475 ways: When set to 1, complex merge checks are disabled, but the 476 simple one-shot merges with the previous I/O request are 477 enabled. When set to 2, all merge tries are disabled. The 478 default value is 0 - which enables all types of merge tries. 479 480 481What: /sys/block/<disk>/queue/nr_requests 482Date: July 2003 483Contact: linux-block@vger.kernel.org 484Description: 485 [RW] This controls how many requests may be allocated in the 486 block layer for read or write requests. Note that the total 487 allocated number may be twice this amount, since it applies only 488 to reads or writes (not the accumulated sum). 489 490 To avoid priority inversion through request starvation, a 491 request queue maintains a separate request pool per each cgroup 492 when CONFIG_BLK_CGROUP is enabled, and this parameter applies to 493 each such per-block-cgroup request pool. IOW, if there are N 494 block cgroups, each request queue may have up to N request 495 pools, each independently regulated by nr_requests. 496 497 498What: /sys/block/<disk>/queue/nr_zones 499Date: November 2018 500Contact: Damien Le Moal <damien.lemoal@wdc.com> 501Description: 502 [RO] nr_zones indicates the total number of zones of a zoned 503 block device ("host-aware" or "host-managed" zone model). For 504 regular block devices, the value is always 0. 505 506 507What: /sys/block/<disk>/queue/optimal_io_size 508Date: April 2009 509Contact: Martin K. Petersen <martin.petersen@oracle.com> 510Description: 511 [RO] Storage devices may report an optimal I/O size, which is 512 the device's preferred unit for sustained I/O. This is rarely 513 reported for disk drives. For RAID arrays it is usually the 514 stripe width or the internal track size. A properly aligned 515 multiple of optimal_io_size is the preferred request size for 516 workloads where sustained throughput is desired. If no optimal 517 I/O size is reported this file contains 0. 518 519 520What: /sys/block/<disk>/queue/physical_block_size 521Date: May 2009 522Contact: Martin K. Petersen <martin.petersen@oracle.com> 523Description: 524 [RO] This is the smallest unit a physical storage device can 525 write atomically. It is usually the same as the logical block 526 size but may be bigger. One example is SATA drives with 4KB 527 sectors that expose a 512-byte logical block size to the 528 operating system. For stacked block devices the 529 physical_block_size variable contains the maximum 530 physical_block_size of the component devices. 531 532 533What: /sys/block/<disk>/queue/read_ahead_kb 534Date: May 2004 535Contact: linux-block@vger.kernel.org 536Description: 537 [RW] Maximum number of kilobytes to read-ahead for filesystems 538 on this block device. 539 540 541What: /sys/block/<disk>/queue/rotational 542Date: January 2009 543Contact: linux-block@vger.kernel.org 544Description: 545 [RW] This file is used to stat if the device is of rotational 546 type or non-rotational type. 547 548 549What: /sys/block/<disk>/queue/rq_affinity 550Date: September 2008 551Contact: linux-block@vger.kernel.org 552Description: 553 [RW] If this option is '1', the block layer will migrate request 554 completions to the cpu "group" that originally submitted the 555 request. For some workloads this provides a significant 556 reduction in CPU cycles due to caching effects. 557 558 For storage configurations that need to maximize distribution of 559 completion processing setting this option to '2' forces the 560 completion to run on the requesting cpu (bypassing the "group" 561 aggregation logic). 562 563 564What: /sys/block/<disk>/queue/scheduler 565Date: October 2004 566Contact: linux-block@vger.kernel.org 567Description: 568 [RW] When read, this file will display the current and available 569 IO schedulers for this block device. The currently active IO 570 scheduler will be enclosed in [] brackets. Writing an IO 571 scheduler name to this file will switch control of this block 572 device to that new IO scheduler. Note that writing an IO 573 scheduler name to this file will attempt to load that IO 574 scheduler module, if it isn't already present in the system. 575 576 577What: /sys/block/<disk>/queue/stable_writes 578Date: September 2020 579Contact: linux-block@vger.kernel.org 580Description: 581 [RW] This file will contain '1' if memory must not be modified 582 while it is being used in a write request to this device. When 583 this is the case and the kernel is performing writeback of a 584 page, the kernel will wait for writeback to complete before 585 allowing the page to be modified again, rather than allowing 586 immediate modification as is normally the case. This 587 restriction arises when the device accesses the memory multiple 588 times where the same data must be seen every time -- for 589 example, once to calculate a checksum and once to actually write 590 the data. If no such restriction exists, this file will contain 591 '0'. This file is writable for testing purposes. 592 593 594What: /sys/block/<disk>/queue/throttle_sample_time 595Date: March 2017 596Contact: linux-block@vger.kernel.org 597Description: 598 [RW] This is the time window that blk-throttle samples data, in 599 millisecond. blk-throttle makes decision based on the 600 samplings. Lower time means cgroups have more smooth throughput, 601 but higher CPU overhead. This exists only when 602 CONFIG_BLK_DEV_THROTTLING_LOW is enabled. 603 604 605What: /sys/block/<disk>/queue/virt_boundary_mask 606Date: April 2021 607Contact: linux-block@vger.kernel.org 608Description: 609 [RO] This file shows the I/O segment memory alignment mask for 610 the block device. I/O requests to this device will be split 611 between segments wherever either the memory address of the end 612 of the previous segment or the memory address of the beginning 613 of the current segment is not aligned to virt_boundary_mask + 1 614 bytes. 615 616 617What: /sys/block/<disk>/queue/wbt_lat_usec 618Date: November 2016 619Contact: linux-block@vger.kernel.org 620Description: 621 [RW] If the device is registered for writeback throttling, then 622 this file shows the target minimum read latency. If this latency 623 is exceeded in a given window of time (see wb_window_usec), then 624 the writeback throttling will start scaling back writes. Writing 625 a value of '0' to this file disables the feature. Writing a 626 value of '-1' to this file resets the value to the default 627 setting. 628 629 630What: /sys/block/<disk>/queue/write_cache 631Date: April 2016 632Contact: linux-block@vger.kernel.org 633Description: 634 [RW] When read, this file will display whether the device has 635 write back caching enabled or not. It will return "write back" 636 for the former case, and "write through" for the latter. Writing 637 to this file can change the kernels view of the device, but it 638 doesn't alter the device state. This means that it might not be 639 safe to toggle the setting from "write back" to "write through", 640 since that will also eliminate cache flushes issued by the 641 kernel. 642 643 644What: /sys/block/<disk>/queue/write_same_max_bytes 645Date: January 2012 646Contact: Martin K. Petersen <martin.petersen@oracle.com> 647Description: 648 [RO] Some devices support a write same operation in which a 649 single data block can be written to a range of several 650 contiguous blocks on storage. This can be used to wipe areas on 651 disk or to initialize drives in a RAID configuration. 652 write_same_max_bytes indicates how many bytes can be written in 653 a single write same command. If write_same_max_bytes is 0, write 654 same is not supported by the device. 655 656 657What: /sys/block/<disk>/queue/write_zeroes_max_bytes 658Date: November 2016 659Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> 660Description: 661 [RO] Devices that support write zeroes operation in which a 662 single request can be issued to zero out the range of contiguous 663 blocks on storage without having any payload in the request. 664 This can be used to optimize writing zeroes to the devices. 665 write_zeroes_max_bytes indicates how many bytes can be written 666 in a single write zeroes command. If write_zeroes_max_bytes is 667 0, write zeroes is not supported by the device. 668 669 670What: /sys/block/<disk>/queue/zone_append_max_bytes 671Date: May 2020 672Contact: linux-block@vger.kernel.org 673Description: 674 [RO] This is the maximum number of bytes that can be written to 675 a sequential zone of a zoned block device using a zone append 676 write operation (REQ_OP_ZONE_APPEND). This value is always 0 for 677 regular block devices. 678 679 680What: /sys/block/<disk>/queue/zone_write_granularity 681Date: January 2021 682Contact: linux-block@vger.kernel.org 683Description: 684 [RO] This indicates the alignment constraint, in bytes, for 685 write operations in sequential zones of zoned block devices 686 (devices with a zoned attributed that reports "host-managed" or 687 "host-aware"). This value is always 0 for regular block devices. 688 689 690What: /sys/block/<disk>/queue/zoned 691Date: September 2016 692Contact: Damien Le Moal <damien.lemoal@wdc.com> 693Description: 694 [RO] zoned indicates if the device is a zoned block device and 695 the zone model of the device if it is indeed zoned. The 696 possible values indicated by zoned are "none" for regular block 697 devices and "host-aware" or "host-managed" for zoned block 698 devices. The characteristics of host-aware and host-managed 699 zoned block devices are described in the ZBC (Zoned Block 700 Commands) and ZAC (Zoned Device ATA Command Set) standards. 701 These standards also define the "drive-managed" zone model. 702 However, since drive-managed zoned block devices do not support 703 zone commands, they will be treated as regular block devices and 704 zoned will report "none". 705 706 707What: /sys/block/<disk>/stat 708Date: February 2008 709Contact: Jerome Marchand <jmarchan@redhat.com> 710Description: 711 The /sys/block/<disk>/stat files displays the I/O 712 statistics of disk <disk>. They contain 11 fields: 713 714 == ============================================== 715 1 reads completed successfully 716 2 reads merged 717 3 sectors read 718 4 time spent reading (ms) 719 5 writes completed 720 6 writes merged 721 7 sectors written 722 8 time spent writing (ms) 723 9 I/Os currently in progress 724 10 time spent doing I/Os (ms) 725 11 weighted time spent doing I/Os (ms) 726 12 discards completed 727 13 discards merged 728 14 sectors discarded 729 15 time spent discarding (ms) 730 16 flush requests completed 731 17 time spent flushing (ms) 732 == ============================================== 733 734 For more details refer Documentation/admin-guide/iostats.rst 735
