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48920ff2a5
Now that we use the proper REQ_OP_WRITE_ZEROES operation everywhere we can kill this hack. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
274 lines
10 KiB
Plaintext
274 lines
10 KiB
Plaintext
What: /sys/block/<disk>/stat
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Date: February 2008
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Contact: Jerome Marchand <jmarchan@redhat.com>
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Description:
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The /sys/block/<disk>/stat files displays the I/O
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statistics of disk <disk>. They contain 11 fields:
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1 - reads completed successfully
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2 - reads merged
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3 - sectors read
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4 - time spent reading (ms)
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5 - writes completed
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6 - writes merged
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7 - sectors written
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8 - time spent writing (ms)
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9 - I/Os currently in progress
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10 - time spent doing I/Os (ms)
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11 - weighted time spent doing I/Os (ms)
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For more details refer Documentation/iostats.txt
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What: /sys/block/<disk>/<part>/stat
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Date: February 2008
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Contact: Jerome Marchand <jmarchan@redhat.com>
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Description:
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The /sys/block/<disk>/<part>/stat files display the
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I/O statistics of partition <part>. The format is the
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same as the above-written /sys/block/<disk>/stat
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format.
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What: /sys/block/<disk>/integrity/format
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Date: June 2008
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Metadata format for integrity capable block device.
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E.g. T10-DIF-TYPE1-CRC.
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What: /sys/block/<disk>/integrity/read_verify
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Date: June 2008
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Indicates whether the block layer should verify the
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integrity of read requests serviced by devices that
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support sending integrity metadata.
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What: /sys/block/<disk>/integrity/tag_size
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Date: June 2008
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Number of bytes of integrity tag space available per
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512 bytes of data.
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What: /sys/block/<disk>/integrity/device_is_integrity_capable
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Date: July 2014
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Indicates whether a storage device is capable of storing
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integrity metadata. Set if the device is T10 PI-capable.
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What: /sys/block/<disk>/integrity/protection_interval_bytes
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Date: July 2015
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Describes the number of data bytes which are protected
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by one integrity tuple. Typically the device's logical
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block size.
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What: /sys/block/<disk>/integrity/write_generate
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Date: June 2008
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Indicates whether the block layer should automatically
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generate checksums for write requests bound for
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devices that support receiving integrity metadata.
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What: /sys/block/<disk>/alignment_offset
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Date: April 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Storage devices may report a physical block size that is
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bigger than the logical block size (for instance a drive
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with 4KB physical sectors exposing 512-byte logical
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blocks to the operating system). This parameter
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indicates how many bytes the beginning of the device is
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offset from the disk's natural alignment.
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What: /sys/block/<disk>/<partition>/alignment_offset
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Date: April 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Storage devices may report a physical block size that is
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bigger than the logical block size (for instance a drive
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with 4KB physical sectors exposing 512-byte logical
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blocks to the operating system). This parameter
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indicates how many bytes the beginning of the partition
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is offset from the disk's natural alignment.
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What: /sys/block/<disk>/queue/logical_block_size
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Date: May 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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This is the smallest unit the storage device can
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address. It is typically 512 bytes.
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What: /sys/block/<disk>/queue/physical_block_size
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Date: May 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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This is the smallest unit a physical storage device can
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write atomically. It is usually the same as the logical
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block size but may be bigger. One example is SATA
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drives with 4KB sectors that expose a 512-byte logical
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block size to the operating system. For stacked block
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devices the physical_block_size variable contains the
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maximum physical_block_size of the component devices.
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What: /sys/block/<disk>/queue/minimum_io_size
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Date: April 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Storage devices may report a granularity or preferred
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minimum I/O size which is the smallest request the
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device can perform without incurring a performance
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penalty. For disk drives this is often the physical
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block size. For RAID arrays it is often the stripe
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chunk size. A properly aligned multiple of
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minimum_io_size is the preferred request size for
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workloads where a high number of I/O operations is
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desired.
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What: /sys/block/<disk>/queue/optimal_io_size
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Date: April 2009
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Storage devices may report an optimal I/O size, which is
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the device's preferred unit for sustained I/O. This is
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rarely reported for disk drives. For RAID arrays it is
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usually the stripe width or the internal track size. A
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properly aligned multiple of optimal_io_size is the
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preferred request size for workloads where sustained
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throughput is desired. If no optimal I/O size is
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reported this file contains 0.
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What: /sys/block/<disk>/queue/nomerges
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Date: January 2010
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Contact:
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Description:
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Standard I/O elevator operations include attempts to
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merge contiguous I/Os. For known random I/O loads these
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attempts will always fail and result in extra cycles
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being spent in the kernel. This allows one to turn off
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this behavior on one of two ways: When set to 1, complex
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merge checks are disabled, but the simple one-shot merges
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with the previous I/O request are enabled. When set to 2,
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all merge tries are disabled. The default value is 0 -
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which enables all types of merge tries.
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What: /sys/block/<disk>/discard_alignment
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Date: May 2011
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Devices that support discard functionality may
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internally allocate space in units that are bigger than
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the exported logical block size. The discard_alignment
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parameter indicates how many bytes the beginning of the
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device is offset from the internal allocation unit's
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natural alignment.
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What: /sys/block/<disk>/<partition>/discard_alignment
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Date: May 2011
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Devices that support discard functionality may
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internally allocate space in units that are bigger than
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the exported logical block size. The discard_alignment
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parameter indicates how many bytes the beginning of the
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partition is offset from the internal allocation unit's
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natural alignment.
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What: /sys/block/<disk>/queue/discard_granularity
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Date: May 2011
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Devices that support discard functionality may
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internally allocate space using units that are bigger
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than the logical block size. The discard_granularity
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parameter indicates the size of the internal allocation
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unit in bytes if reported by the device. Otherwise the
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discard_granularity will be set to match the device's
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physical block size. A discard_granularity of 0 means
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that the device does not support discard functionality.
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What: /sys/block/<disk>/queue/discard_max_bytes
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Date: May 2011
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Devices that support discard functionality may have
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internal limits on the number of bytes that can be
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trimmed or unmapped in a single operation. Some storage
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protocols also have inherent limits on the number of
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blocks that can be described in a single command. The
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discard_max_bytes parameter is set by the device driver
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to the maximum number of bytes that can be discarded in
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a single operation. Discard requests issued to the
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device must not exceed this limit. A discard_max_bytes
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value of 0 means that the device does not support
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discard functionality.
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What: /sys/block/<disk>/queue/discard_zeroes_data
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Date: May 2011
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Will always return 0. Don't rely on any specific behavior
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for discards, and don't read this file.
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What: /sys/block/<disk>/queue/write_same_max_bytes
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Date: January 2012
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Contact: Martin K. Petersen <martin.petersen@oracle.com>
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Description:
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Some devices support a write same operation in which a
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single data block can be written to a range of several
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contiguous blocks on storage. This can be used to wipe
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areas on disk or to initialize drives in a RAID
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configuration. write_same_max_bytes indicates how many
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bytes can be written in a single write same command. If
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write_same_max_bytes is 0, write same is not supported
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by the device.
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What: /sys/block/<disk>/queue/write_zeroes_max_bytes
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Date: November 2016
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Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
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Description:
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Devices that support write zeroes operation in which a
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single request can be issued to zero out the range of
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contiguous blocks on storage without having any payload
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in the request. This can be used to optimize writing zeroes
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to the devices. write_zeroes_max_bytes indicates how many
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bytes can be written in a single write zeroes command. If
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write_zeroes_max_bytes is 0, write zeroes is not supported
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by the device.
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What: /sys/block/<disk>/queue/zoned
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Date: September 2016
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Contact: Damien Le Moal <damien.lemoal@hgst.com>
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Description:
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zoned indicates if the device is a zoned block device
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and the zone model of the device if it is indeed zoned.
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The possible values indicated by zoned are "none" for
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regular block devices and "host-aware" or "host-managed"
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for zoned block devices. The characteristics of
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host-aware and host-managed zoned block devices are
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described in the ZBC (Zoned Block Commands) and ZAC
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(Zoned Device ATA Command Set) standards. These standards
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also define the "drive-managed" zone model. However,
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since drive-managed zoned block devices do not support
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zone commands, they will be treated as regular block
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devices and zoned will report "none".
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What: /sys/block/<disk>/queue/chunk_sectors
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Date: September 2016
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Contact: Hannes Reinecke <hare@suse.com>
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Description:
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chunk_sectors has different meaning depending on the type
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of the disk. For a RAID device (dm-raid), chunk_sectors
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indicates the size in 512B sectors of the RAID volume
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stripe segment. For a zoned block device, either
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host-aware or host-managed, chunk_sectors indicates the
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size of 512B sectors of the zones of the device, with
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the eventual exception of the last zone of the device
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which may be smaller.
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