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:
|
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/<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.
|
