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 advertises 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] This was used to control what kind of polling will be 340 performed. It is now fixed to -1, which is classic polling. 341 In this mode, the CPU will repeatedly ask for completions 342 without giving up any time. 343 <deprecated> 344 345 346What: /sys/block/<disk>/queue/io_timeout 347Date: November 2018 348Contact: Weiping Zhang <zhangweiping@didiglobal.com> 349Description: 350 [RW] io_timeout is the request timeout in milliseconds. If a 351 request does not complete in this time then the block driver 352 timeout handler is invoked. That timeout handler can decide to 353 retry the request, to fail it or to start a device recovery 354 strategy. 355 356 357What: /sys/block/<disk>/queue/iostats 358Date: January 2009 359Contact: linux-block@vger.kernel.org 360Description: 361 [RW] This file is used to control (on/off) the iostats 362 accounting of the disk. 363 364 365What: /sys/block/<disk>/queue/logical_block_size 366Date: May 2009 367Contact: Martin K. Petersen <martin.petersen@oracle.com> 368Description: 369 [RO] This is the smallest unit the storage device can address. 370 It is typically 512 bytes. 371 372 373What: /sys/block/<disk>/queue/max_active_zones 374Date: July 2020 375Contact: Niklas Cassel <niklas.cassel@wdc.com> 376Description: 377 [RO] For zoned block devices (zoned attribute indicating 378 "host-managed" or "host-aware"), the sum of zones belonging to 379 any of the zone states: EXPLICIT OPEN, IMPLICIT OPEN or CLOSED, 380 is limited by this value. If this value is 0, there is no limit. 381 382 If the host attempts to exceed this limit, the driver should 383 report this error with BLK_STS_ZONE_ACTIVE_RESOURCE, which user 384 space may see as the EOVERFLOW errno. 385 386 387What: /sys/block/<disk>/queue/max_discard_segments 388Date: February 2017 389Contact: linux-block@vger.kernel.org 390Description: 391 [RO] The maximum number of DMA scatter/gather entries in a 392 discard request. 393 394 395What: /sys/block/<disk>/queue/max_hw_sectors_kb 396Date: September 2004 397Contact: linux-block@vger.kernel.org 398Description: 399 [RO] This is the maximum number of kilobytes supported in a 400 single data transfer. 401 402 403What: /sys/block/<disk>/queue/max_integrity_segments 404Date: September 2010 405Contact: linux-block@vger.kernel.org 406Description: 407 [RO] Maximum number of elements in a DMA scatter/gather list 408 with integrity data that will be submitted by the block layer 409 core to the associated block driver. 410 411 412What: /sys/block/<disk>/queue/max_open_zones 413Date: July 2020 414Contact: Niklas Cassel <niklas.cassel@wdc.com> 415Description: 416 [RO] For zoned block devices (zoned attribute indicating 417 "host-managed" or "host-aware"), the sum of zones belonging to 418 any of the zone states: EXPLICIT OPEN or IMPLICIT OPEN, is 419 limited by this value. If this value is 0, there is no limit. 420 421 422What: /sys/block/<disk>/queue/max_sectors_kb 423Date: September 2004 424Contact: linux-block@vger.kernel.org 425Description: 426 [RW] This is the maximum number of kilobytes that the block 427 layer will allow for a filesystem request. Must be smaller than 428 or equal to the maximum size allowed by the hardware. Write 0 429 to use default kernel settings. 430 431 432What: /sys/block/<disk>/queue/max_segment_size 433Date: March 2010 434Contact: linux-block@vger.kernel.org 435Description: 436 [RO] Maximum size in bytes of a single element in a DMA 437 scatter/gather list. 438 439 440What: /sys/block/<disk>/queue/max_segments 441Date: March 2010 442Contact: linux-block@vger.kernel.org 443Description: 444 [RO] Maximum number of elements in a DMA scatter/gather list 445 that is submitted to the associated block driver. 446 447 448What: /sys/block/<disk>/queue/minimum_io_size 449Date: April 2009 450Contact: Martin K. Petersen <martin.petersen@oracle.com> 451Description: 452 [RO] Storage devices may report a granularity or preferred 453 minimum I/O size which is the smallest request the device can 454 perform without incurring a performance penalty. For disk 455 drives this is often the physical block size. For RAID arrays 456 it is often the stripe chunk size. A properly aligned multiple 457 of minimum_io_size is the preferred request size for workloads 458 where a high number of I/O operations is desired. 459 460 461What: /sys/block/<disk>/queue/nomerges 462Date: January 2010 463Contact: linux-block@vger.kernel.org 464Description: 465 [RW] Standard I/O elevator operations include attempts to merge 466 contiguous I/Os. For known random I/O loads these attempts will 467 always fail and result in extra cycles being spent in the 468 kernel. This allows one to turn off this behavior on one of two 469 ways: When set to 1, complex merge checks are disabled, but the 470 simple one-shot merges with the previous I/O request are 471 enabled. When set to 2, all merge tries are disabled. The 472 default value is 0 - which enables all types of merge tries. 473 474 475What: /sys/block/<disk>/queue/nr_requests 476Date: July 2003 477Contact: linux-block@vger.kernel.org 478Description: 479 [RW] This controls how many requests may be allocated in the 480 block layer for read or write requests. Note that the total 481 allocated number may be twice this amount, since it applies only 482 to reads or writes (not the accumulated sum). 483 484 To avoid priority inversion through request starvation, a 485 request queue maintains a separate request pool per each cgroup 486 when CONFIG_BLK_CGROUP is enabled, and this parameter applies to 487 each such per-block-cgroup request pool. IOW, if there are N 488 block cgroups, each request queue may have up to N request 489 pools, each independently regulated by nr_requests. 490 491 492What: /sys/block/<disk>/queue/nr_zones 493Date: November 2018 494Contact: Damien Le Moal <damien.lemoal@wdc.com> 495Description: 496 [RO] nr_zones indicates the total number of zones of a zoned 497 block device ("host-aware" or "host-managed" zone model). For 498 regular block devices, the value is always 0. 499 500 501What: /sys/block/<disk>/queue/optimal_io_size 502Date: April 2009 503Contact: Martin K. Petersen <martin.petersen@oracle.com> 504Description: 505 [RO] Storage devices may report an optimal I/O size, which is 506 the device's preferred unit for sustained I/O. This is rarely 507 reported for disk drives. For RAID arrays it is usually the 508 stripe width or the internal track size. A properly aligned 509 multiple of optimal_io_size is the preferred request size for 510 workloads where sustained throughput is desired. If no optimal 511 I/O size is reported this file contains 0. 512 513 514What: /sys/block/<disk>/queue/physical_block_size 515Date: May 2009 516Contact: Martin K. Petersen <martin.petersen@oracle.com> 517Description: 518 [RO] This is the smallest unit a physical storage device can 519 write atomically. It is usually the same as the logical block 520 size but may be bigger. One example is SATA drives with 4KB 521 sectors that expose a 512-byte logical block size to the 522 operating system. For stacked block devices the 523 physical_block_size variable contains the maximum 524 physical_block_size of the component devices. 525 526 527What: /sys/block/<disk>/queue/read_ahead_kb 528Date: May 2004 529Contact: linux-block@vger.kernel.org 530Description: 531 [RW] Maximum number of kilobytes to read-ahead for filesystems 532 on this block device. 533 534 535What: /sys/block/<disk>/queue/rotational 536Date: January 2009 537Contact: linux-block@vger.kernel.org 538Description: 539 [RW] This file is used to stat if the device is of rotational 540 type or non-rotational type. 541 542 543What: /sys/block/<disk>/queue/rq_affinity 544Date: September 2008 545Contact: linux-block@vger.kernel.org 546Description: 547 [RW] If this option is '1', the block layer will migrate request 548 completions to the cpu "group" that originally submitted the 549 request. For some workloads this provides a significant 550 reduction in CPU cycles due to caching effects. 551 552 For storage configurations that need to maximize distribution of 553 completion processing setting this option to '2' forces the 554 completion to run on the requesting cpu (bypassing the "group" 555 aggregation logic). 556 557 558What: /sys/block/<disk>/queue/scheduler 559Date: October 2004 560Contact: linux-block@vger.kernel.org 561Description: 562 [RW] When read, this file will display the current and available 563 IO schedulers for this block device. The currently active IO 564 scheduler will be enclosed in [] brackets. Writing an IO 565 scheduler name to this file will switch control of this block 566 device to that new IO scheduler. Note that writing an IO 567 scheduler name to this file will attempt to load that IO 568 scheduler module, if it isn't already present in the system. 569 570 571What: /sys/block/<disk>/queue/stable_writes 572Date: September 2020 573Contact: linux-block@vger.kernel.org 574Description: 575 [RW] This file will contain '1' if memory must not be modified 576 while it is being used in a write request to this device. When 577 this is the case and the kernel is performing writeback of a 578 page, the kernel will wait for writeback to complete before 579 allowing the page to be modified again, rather than allowing 580 immediate modification as is normally the case. This 581 restriction arises when the device accesses the memory multiple 582 times where the same data must be seen every time -- for 583 example, once to calculate a checksum and once to actually write 584 the data. If no such restriction exists, this file will contain 585 '0'. This file is writable for testing purposes. 586 587 588What: /sys/block/<disk>/queue/throttle_sample_time 589Date: March 2017 590Contact: linux-block@vger.kernel.org 591Description: 592 [RW] This is the time window that blk-throttle samples data, in 593 millisecond. blk-throttle makes decision based on the 594 samplings. Lower time means cgroups have more smooth throughput, 595 but higher CPU overhead. This exists only when 596 CONFIG_BLK_DEV_THROTTLING_LOW is enabled. 597 598 599What: /sys/block/<disk>/queue/virt_boundary_mask 600Date: April 2021 601Contact: linux-block@vger.kernel.org 602Description: 603 [RO] This file shows the I/O segment memory alignment mask for 604 the block device. I/O requests to this device will be split 605 between segments wherever either the memory address of the end 606 of the previous segment or the memory address of the beginning 607 of the current segment is not aligned to virt_boundary_mask + 1 608 bytes. 609 610 611What: /sys/block/<disk>/queue/wbt_lat_usec 612Date: November 2016 613Contact: linux-block@vger.kernel.org 614Description: 615 [RW] If the device is registered for writeback throttling, then 616 this file shows the target minimum read latency. If this latency 617 is exceeded in a given window of time (see wb_window_usec), then 618 the writeback throttling will start scaling back writes. Writing 619 a value of '0' to this file disables the feature. Writing a 620 value of '-1' to this file resets the value to the default 621 setting. 622 623 624What: /sys/block/<disk>/queue/write_cache 625Date: April 2016 626Contact: linux-block@vger.kernel.org 627Description: 628 [RW] When read, this file will display whether the device has 629 write back caching enabled or not. It will return "write back" 630 for the former case, and "write through" for the latter. Writing 631 to this file can change the kernels view of the device, but it 632 doesn't alter the device state. This means that it might not be 633 safe to toggle the setting from "write back" to "write through", 634 since that will also eliminate cache flushes issued by the 635 kernel. 636 637 638What: /sys/block/<disk>/queue/write_same_max_bytes 639Date: January 2012 640Contact: Martin K. Petersen <martin.petersen@oracle.com> 641Description: 642 [RO] Some devices support a write same operation in which a 643 single data block can be written to a range of several 644 contiguous blocks on storage. This can be used to wipe areas on 645 disk or to initialize drives in a RAID configuration. 646 write_same_max_bytes indicates how many bytes can be written in 647 a single write same command. If write_same_max_bytes is 0, write 648 same is not supported by the device. 649 650 651What: /sys/block/<disk>/queue/write_zeroes_max_bytes 652Date: November 2016 653Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> 654Description: 655 [RO] Devices that support write zeroes operation in which a 656 single request can be issued to zero out the range of contiguous 657 blocks on storage without having any payload in the request. 658 This can be used to optimize writing zeroes to the devices. 659 write_zeroes_max_bytes indicates how many bytes can be written 660 in a single write zeroes command. If write_zeroes_max_bytes is 661 0, write zeroes is not supported by the device. 662 663 664What: /sys/block/<disk>/queue/zone_append_max_bytes 665Date: May 2020 666Contact: linux-block@vger.kernel.org 667Description: 668 [RO] This is the maximum number of bytes that can be written to 669 a sequential zone of a zoned block device using a zone append 670 write operation (REQ_OP_ZONE_APPEND). This value is always 0 for 671 regular block devices. 672 673 674What: /sys/block/<disk>/queue/zone_write_granularity 675Date: January 2021 676Contact: linux-block@vger.kernel.org 677Description: 678 [RO] This indicates the alignment constraint, in bytes, for 679 write operations in sequential zones of zoned block devices 680 (devices with a zoned attributed that reports "host-managed" or 681 "host-aware"). This value is always 0 for regular block devices. 682 683 684What: /sys/block/<disk>/queue/zoned 685Date: September 2016 686Contact: Damien Le Moal <damien.lemoal@wdc.com> 687Description: 688 [RO] zoned indicates if the device is a zoned block device and 689 the zone model of the device if it is indeed zoned. The 690 possible values indicated by zoned are "none" for regular block 691 devices and "host-aware" or "host-managed" for zoned block 692 devices. The characteristics of host-aware and host-managed 693 zoned block devices are described in the ZBC (Zoned Block 694 Commands) and ZAC (Zoned Device ATA Command Set) standards. 695 These standards also define the "drive-managed" zone model. 696 However, since drive-managed zoned block devices do not support 697 zone commands, they will be treated as regular block devices and 698 zoned will report "none". 699 700 701What: /sys/block/<disk>/hidden 702Date: March 2023 703Contact: linux-block@vger.kernel.org 704Description: 705 [RO] the block device is hidden. it doesn’t produce events, and 706 can’t be opened from userspace or using blkdev_get*. 707 Used for the underlying components of multipath devices. 708 709 710What: /sys/block/<disk>/stat 711Date: February 2008 712Contact: Jerome Marchand <jmarchan@redhat.com> 713Description: 714 The /sys/block/<disk>/stat files displays the I/O 715 statistics of disk <disk>. They contain 11 fields: 716 717 == ============================================== 718 1 reads completed successfully 719 2 reads merged 720 3 sectors read 721 4 time spent reading (ms) 722 5 writes completed 723 6 writes merged 724 7 sectors written 725 8 time spent writing (ms) 726 9 I/Os currently in progress 727 10 time spent doing I/Os (ms) 728 11 weighted time spent doing I/Os (ms) 729 12 discards completed 730 13 discards merged 731 14 sectors discarded 732 15 time spent discarding (ms) 733 16 flush requests completed 734 17 time spent flushing (ms) 735 == ============================================== 736 737 For more details refer Documentation/admin-guide/iostats.rst 738
