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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)
+ For more details refer Documentation/iostats.txt
+
+
+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@hgst.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/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 of 512B sectors of the zones of the device, with
+ the eventual exception of the last zone of the device
+ which may be smaller.