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diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block new file mode 100644 index 000000000000..b16b0c45a272 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-block @@ -0,0 +1,346 @@ +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>/inflight +Date: October 2009 +Contact: Jens Axboe <axboe@kernel.dk>, Nikanth Karthikesan <knikanth@suse.de> +Description: + Reports the number of I/O requests currently in progress + (pending / in flight) in a device driver. This can be less + than the number of requests queued in the block device queue. + The report contains 2 fields: one for read requests + and one for write requests. + The value type is unsigned int. + Cf. Documentation/block/stat.rst which contains a single value for + requests in flight. + This is related to nr_requests in Documentation/block/queue-sysfs.rst + and for SCSI device also its queue_depth. + + +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>/<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. |