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@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/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.