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>/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>/atomic_write_max_bytes
Date:		February 2024
Contact:	Himanshu Madhani <himanshu.madhani@oracle.com>
Description:
		[RO] This parameter specifies the maximum atomic write
		size reported by the device. This parameter is relevant
		for merging of writes, where a merged atomic write
		operation must not exceed this number of bytes.
		This parameter may be greater than the value in
		atomic_write_unit_max_bytes as
		atomic_write_unit_max_bytes will be rounded down to a
		power-of-two and atomic_write_unit_max_bytes may also be
		limited by some other queue limits, such as max_segments.
		This parameter - along with atomic_write_unit_min_bytes
		and atomic_write_unit_max_bytes - will not be larger than
		max_hw_sectors_kb, but may be larger than max_sectors_kb.


What:		/sys/block/<disk>/atomic_write_unit_min_bytes
Date:		February 2024
Contact:	Himanshu Madhani <himanshu.madhani@oracle.com>
Description:
		[RO] This parameter specifies the smallest block which can
		be written atomically with an atomic write operation. All
		atomic write operations must begin at a
		atomic_write_unit_min boundary and must be multiples of
		atomic_write_unit_min. This value must be a power-of-two.


What:		/sys/block/<disk>/atomic_write_unit_max_bytes
Date:		February 2024
Contact:	Himanshu Madhani <himanshu.madhani@oracle.com>
Description:
		[RO] This parameter defines the largest block which can be
		written atomically with an atomic write operation. This
		value must be a multiple of atomic_write_unit_min and must
		be a power-of-two. This value will not be larger than
		atomic_write_max_bytes.


What:		/sys/block/<disk>/atomic_write_boundary_bytes
Date:		February 2024
Contact:	Himanshu Madhani <himanshu.madhani@oracle.com>
Description:
		[RO] A device may need to internally split an atomic write I/O
		which straddles a given logical block address boundary. This
		parameter specifies the size in bytes of the atomic boundary if
		one is reported by the device. This value must be a
		power-of-two and at least the size as in
		atomic_write_unit_max_bytes.
		Any attempt to merge atomic write I/Os must not result in a
		merged I/O which crosses this boundary (if any).


What:		/sys/block/<disk>/diskseq
Date:		February 2021
Contact:	Matteo Croce <mcroce@microsoft.com>
Description:
		The /sys/block/<disk>/diskseq files reports the disk
		sequence number, which is a monotonically increasing
		number assigned to every drive.
		Some devices, like the loop device, refresh such number
		every time the backing file is changed.
		The value type is 64 bit unsigned.


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/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/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/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/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>/partscan
Date:		May 2024
Contact:	Christoph Hellwig <hch@lst.de>
Description:
		The /sys/block/<disk>/partscan files reports if partition
		scanning is enabled for the disk.  It returns "1" if partition
		scanning is enabled, or "0" if not.  The value type is a 32-bit
		unsigned integer, but only "0" and "1" are valid values.


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>/<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>/<partition>/stat
Date:		February 2008
Contact:	Jerome Marchand <jmarchan@redhat.com>
Description:
		The /sys/block/<disk>/<partition>/stat files display the
		I/O statistics of partition <partition>. The format is the
		same as the format of /sys/block/<disk>/stat.


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/crypto/
Date:		February 2022
Contact:	linux-block@vger.kernel.org
Description:
		The presence of this subdirectory of /sys/block/<disk>/queue/
		indicates that the device supports inline encryption.  This
		subdirectory contains files which describe the inline encryption
		capabilities of the device.  For more information about inline
		encryption, refer to Documentation/block/inline-encryption.rst.


What:		/sys/block/<disk>/queue/crypto/max_dun_bits
Date:		February 2022
Contact:	linux-block@vger.kernel.org
Description:
		[RO] This file shows the maximum length, in bits, of data unit
		numbers accepted by the device in inline encryption requests.


What:		/sys/block/<disk>/queue/crypto/modes/<mode>
Date:		February 2022
Contact:	linux-block@vger.kernel.org
Description:
		[RO] For each crypto mode (i.e., encryption/decryption
		algorithm) the device supports with inline encryption, a file
		will exist at this location.  It will contain a hexadecimal
		number that is a bitmask of the supported data unit sizes, in
		bytes, for that crypto mode.

		Currently, the crypto modes that may be supported are:

		   * AES-256-XTS
		   * AES-128-CBC-ESSIV
		   * Adiantum

		For example, if a device supports AES-256-XTS inline encryption
		with data unit sizes of 512 and 4096 bytes, the file
		/sys/block/<disk>/queue/crypto/modes/AES-256-XTS will exist and
		will contain "0x1200".


What:		/sys/block/<disk>/queue/crypto/num_keyslots
Date:		February 2022
Contact:	linux-block@vger.kernel.org
Description:
		[RO] This file shows the number of keyslots the device has for
		use with inline encryption.


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/dma_alignment
Date:		May 2022
Contact:	linux-block@vger.kernel.org
Description:
		Reports the alignment that user space addresses must have to be
		used for raw block device access with O_DIRECT and other driver
		specific passthrough mechanisms.

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.


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/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/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/nomerges
Date:		January 2010
Contact:	linux-block@vger.kernel.org
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>/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/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/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/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/iostats_passthrough
Date:		October 2024
Contact:	linux-block@vger.kernel.org
Description:
		[RW] This file is used to control (on/off) the iostats
		accounting of the disk for passthrough commands.


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>/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
