What: /sys/block//stat Date: February 2008 Contact: Jerome Marchand Description: The /sys/block//stat files displays the I/O statistics of 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///stat Date: February 2008 Contact: Jerome Marchand Description: The /sys/block///stat files display the I/O statistics of partition . The format is the same as the above-written /sys/block//stat format. What: /sys/block//integrity/format Date: June 2008 Contact: Martin K. Petersen Description: Metadata format for integrity capable block device. E.g. T10-DIF-TYPE1-CRC. What: /sys/block//integrity/read_verify Date: June 2008 Contact: Martin K. Petersen Description: Indicates whether the block layer should verify the integrity of read requests serviced by devices that support sending integrity metadata. What: /sys/block//integrity/tag_size Date: June 2008 Contact: Martin K. Petersen Description: Number of bytes of integrity tag space available per 512 bytes of data. What: /sys/block//integrity/write_generate Date: June 2008 Contact: Martin K. Petersen Description: Indicates whether the block layer should automatically generate checksums for write requests bound for devices that support receiving integrity metadata. What: /sys/block//alignment_offset Date: April 2009 Contact: Martin K. Petersen 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///alignment_offset Date: April 2009 Contact: Martin K. Petersen 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//queue/logical_block_size Date: May 2009 Contact: Martin K. Petersen Description: This is the smallest unit the storage device can address. It is typically 512 bytes. What: /sys/block//queue/physical_block_size Date: May 2009 Contact: Martin K. Petersen 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//queue/minimum_io_size Date: April 2009 Contact: Martin K. Petersen 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//queue/optimal_io_size Date: April 2009 Contact: Martin K. Petersen 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//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//discard_alignment Date: May 2011 Contact: Martin K. Petersen 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///discard_alignment Date: May 2011 Contact: Martin K. Petersen 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//queue/discard_granularity Date: May 2011 Contact: Martin K. Petersen 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//queue/discard_max_bytes Date: May 2011 Contact: Martin K. Petersen 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//queue/discard_zeroes_data Date: May 2011 Contact: Martin K. Petersen Description: Devices that support discard functionality may return stale or random data when a previously discarded block is read back. This can cause problems if the filesystem expects discarded blocks to be explicitly cleared. If a device reports that it deterministically returns zeroes when a discarded area is read the discard_zeroes_data parameter will be set to one. Otherwise it will be 0 and the result of reading a discarded area is undefined. What: /sys/block//alias Date: Aug 2011 Contact: Nao Nishijima Description: A raw device name of a disk does not always point a same disk each boot-up time. Therefore, users have to use persistent device names, which udev creates when the kernel finds a disk, instead of raw device name. However, kernel doesn't show those persistent names on its messages (e.g. dmesg). This file can store an alias of the disk and it would be appeared in kernel messages if it is set. A disk can have an alias which length is up to 255bytes. Users can use alphabets, numbers, "-" and "_" in alias name. This file is writeonce.