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- What: /sys/block/<disk>/stat
- Date: February 2008
- Contact: Jerome Marchand <jmarchan@redhat.com>
- Description:
- The /sys/block/<disk>/stat files displays the I/O
- statistics of disk <disk>. They contain 11 fields:
- == ==============================================
- 1 reads completed successfully
- 2 reads merged
- 3 sectors read
- 4 time spent reading (ms)
- 5 writes completed
- 6 writes merged
- 7 sectors written
- 8 time spent writing (ms)
- 9 I/Os currently in progress
- 10 time spent doing I/Os (ms)
- 11 weighted time spent doing I/Os (ms)
- 12 discards completed
- 13 discards merged
- 14 sectors discarded
- 15 time spent discarding (ms)
- 16 flush requests completed
- 17 time spent flushing (ms)
- == ==============================================
- For more details refer Documentation/admin-guide/iostats.rst
- What: /sys/block/<disk>/<part>/stat
- Date: February 2008
- Contact: Jerome Marchand <jmarchan@redhat.com>
- Description:
- The /sys/block/<disk>/<part>/stat files display the
- I/O statistics of partition <part>. The format is the
- same as the above-written /sys/block/<disk>/stat
- format.
- What: /sys/block/<disk>/integrity/format
- Date: June 2008
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Metadata format for integrity capable block device.
- E.g. T10-DIF-TYPE1-CRC.
- What: /sys/block/<disk>/integrity/read_verify
- Date: June 2008
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Indicates whether the block layer should verify the
- integrity of read requests serviced by devices that
- support sending integrity metadata.
- What: /sys/block/<disk>/integrity/tag_size
- Date: June 2008
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Number of bytes of integrity tag space available per
- 512 bytes of data.
- What: /sys/block/<disk>/integrity/device_is_integrity_capable
- Date: July 2014
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Indicates whether a storage device is capable of storing
- integrity metadata. Set if the device is T10 PI-capable.
- What: /sys/block/<disk>/integrity/protection_interval_bytes
- Date: July 2015
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Describes the number of data bytes which are protected
- by one integrity tuple. Typically the device's logical
- block size.
- What: /sys/block/<disk>/integrity/write_generate
- Date: June 2008
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Indicates whether the block layer should automatically
- generate checksums for write requests bound for
- devices that support receiving integrity metadata.
- What: /sys/block/<disk>/alignment_offset
- Date: April 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Storage devices may report a physical block size that is
- bigger than the logical block size (for instance a drive
- with 4KB physical sectors exposing 512-byte logical
- blocks to the operating system). This parameter
- indicates how many bytes the beginning of the device is
- offset from the disk's natural alignment.
- What: /sys/block/<disk>/<partition>/alignment_offset
- Date: April 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Storage devices may report a physical block size that is
- bigger than the logical block size (for instance a drive
- with 4KB physical sectors exposing 512-byte logical
- blocks to the operating system). This parameter
- indicates how many bytes the beginning of the partition
- is offset from the disk's natural alignment.
- What: /sys/block/<disk>/queue/logical_block_size
- Date: May 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- This is the smallest unit the storage device can
- address. It is typically 512 bytes.
- What: /sys/block/<disk>/queue/physical_block_size
- Date: May 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- This is the smallest unit a physical storage device can
- write atomically. It is usually the same as the logical
- block size but may be bigger. One example is SATA
- drives with 4KB sectors that expose a 512-byte logical
- block size to the operating system. For stacked block
- devices the physical_block_size variable contains the
- maximum physical_block_size of the component devices.
- What: /sys/block/<disk>/queue/minimum_io_size
- Date: April 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Storage devices may report a granularity or preferred
- minimum I/O size which is the smallest request the
- device can perform without incurring a performance
- penalty. For disk drives this is often the physical
- block size. For RAID arrays it is often the stripe
- chunk size. A properly aligned multiple of
- minimum_io_size is the preferred request size for
- workloads where a high number of I/O operations is
- desired.
- What: /sys/block/<disk>/queue/optimal_io_size
- Date: April 2009
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Storage devices may report an optimal I/O size, which is
- the device's preferred unit for sustained I/O. This is
- rarely reported for disk drives. For RAID arrays it is
- usually the stripe width or the internal track size. A
- properly aligned multiple of optimal_io_size is the
- preferred request size for workloads where sustained
- throughput is desired. If no optimal I/O size is
- reported this file contains 0.
- What: /sys/block/<disk>/queue/nomerges
- Date: January 2010
- Contact:
- Description:
- Standard I/O elevator operations include attempts to
- merge contiguous I/Os. For known random I/O loads these
- attempts will always fail and result in extra cycles
- being spent in the kernel. This allows one to turn off
- this behavior on one of two ways: When set to 1, complex
- merge checks are disabled, but the simple one-shot merges
- with the previous I/O request are enabled. When set to 2,
- all merge tries are disabled. The default value is 0 -
- which enables all types of merge tries.
- What: /sys/block/<disk>/discard_alignment
- Date: May 2011
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Devices that support discard functionality may
- internally allocate space in units that are bigger than
- the exported logical block size. The discard_alignment
- parameter indicates how many bytes the beginning of the
- device is offset from the internal allocation unit's
- natural alignment.
- What: /sys/block/<disk>/<partition>/discard_alignment
- Date: May 2011
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Devices that support discard functionality may
- internally allocate space in units that are bigger than
- the exported logical block size. The discard_alignment
- parameter indicates how many bytes the beginning of the
- partition is offset from the internal allocation unit's
- natural alignment.
- What: /sys/block/<disk>/queue/discard_granularity
- Date: May 2011
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Devices that support discard functionality may
- internally allocate space using units that are bigger
- than the logical block size. The discard_granularity
- parameter indicates the size of the internal allocation
- unit in bytes if reported by the device. Otherwise the
- discard_granularity will be set to match the device's
- physical block size. A discard_granularity of 0 means
- that the device does not support discard functionality.
- What: /sys/block/<disk>/queue/discard_max_bytes
- Date: May 2011
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Devices that support discard functionality may have
- internal limits on the number of bytes that can be
- trimmed or unmapped in a single operation. Some storage
- protocols also have inherent limits on the number of
- blocks that can be described in a single command. The
- discard_max_bytes parameter is set by the device driver
- to the maximum number of bytes that can be discarded in
- a single operation. Discard requests issued to the
- device must not exceed this limit. A discard_max_bytes
- value of 0 means that the device does not support
- discard functionality.
- What: /sys/block/<disk>/queue/discard_zeroes_data
- Date: May 2011
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Will always return 0. Don't rely on any specific behavior
- for discards, and don't read this file.
- What: /sys/block/<disk>/queue/write_same_max_bytes
- Date: January 2012
- Contact: Martin K. Petersen <martin.petersen@oracle.com>
- Description:
- Some devices support a write same operation in which a
- single data block can be written to a range of several
- contiguous blocks on storage. This can be used to wipe
- areas on disk or to initialize drives in a RAID
- configuration. write_same_max_bytes indicates how many
- bytes can be written in a single write same command. If
- write_same_max_bytes is 0, write same is not supported
- by the device.
- What: /sys/block/<disk>/queue/write_zeroes_max_bytes
- Date: November 2016
- Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
- Description:
- Devices that support write zeroes operation in which a
- single request can be issued to zero out the range of
- contiguous blocks on storage without having any payload
- in the request. This can be used to optimize writing zeroes
- to the devices. write_zeroes_max_bytes indicates how many
- bytes can be written in a single write zeroes command. If
- write_zeroes_max_bytes is 0, write zeroes is not supported
- by the device.
- What: /sys/block/<disk>/queue/zoned
- Date: September 2016
- Contact: Damien Le Moal <damien.lemoal@wdc.com>
- Description:
- zoned indicates if the device is a zoned block device
- and the zone model of the device if it is indeed zoned.
- The possible values indicated by zoned are "none" for
- regular block devices and "host-aware" or "host-managed"
- for zoned block devices. The characteristics of
- host-aware and host-managed zoned block devices are
- described in the ZBC (Zoned Block Commands) and ZAC
- (Zoned Device ATA Command Set) standards. These standards
- also define the "drive-managed" zone model. However,
- since drive-managed zoned block devices do not support
- zone commands, they will be treated as regular block
- devices and zoned will report "none".
- What: /sys/block/<disk>/queue/nr_zones
- Date: November 2018
- Contact: Damien Le Moal <damien.lemoal@wdc.com>
- Description:
- nr_zones indicates the total number of zones of a zoned block
- device ("host-aware" or "host-managed" zone model). For regular
- block devices, the value is always 0.
- What: /sys/block/<disk>/queue/max_active_zones
- Date: July 2020
- Contact: Niklas Cassel <niklas.cassel@wdc.com>
- Description:
- For zoned block devices (zoned attribute indicating
- "host-managed" or "host-aware"), the sum of zones belonging to
- any of the zone states: EXPLICIT OPEN, IMPLICIT OPEN or CLOSED,
- is limited by this value. If this value is 0, there is no limit.
- What: /sys/block/<disk>/queue/max_open_zones
- Date: July 2020
- Contact: Niklas Cassel <niklas.cassel@wdc.com>
- Description:
- For zoned block devices (zoned attribute indicating
- "host-managed" or "host-aware"), the sum of zones belonging to
- any of the zone states: EXPLICIT OPEN or IMPLICIT OPEN,
- is limited by this value. If this value is 0, there is no limit.
- What: /sys/block/<disk>/queue/chunk_sectors
- Date: September 2016
- Contact: Hannes Reinecke <hare@suse.com>
- Description:
- chunk_sectors has different meaning depending on the type
- of the disk. For a RAID device (dm-raid), chunk_sectors
- indicates the size in 512B sectors of the RAID volume
- stripe segment. For a zoned block device, either
- host-aware or host-managed, chunk_sectors indicates the
- size in 512B sectors of the zones of the device, with
- the eventual exception of the last zone of the device
- which may be smaller.
- What: /sys/block/<disk>/queue/io_timeout
- Date: November 2018
- Contact: Weiping Zhang <zhangweiping@didiglobal.com>
- Description:
- io_timeout is the request timeout in milliseconds. If a request
- does not complete in this time then the block driver timeout
- handler is invoked. That timeout handler can decide to retry
- the request, to fail it or to start a device recovery strategy.
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