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Based on kernel version 4.13.3. Page generated on 2017-09-23 13:54 EST.

1	What:		/sys/block/<disk>/stat
2	Date:		February 2008
3	Contact:	Jerome Marchand <jmarchan@redhat.com>
4	Description:
5			The /sys/block/<disk>/stat files displays the I/O
6			statistics of disk <disk>. They contain 11 fields:
7			 1 - reads completed successfully
8			 2 - reads merged
9			 3 - sectors read
10			 4 - time spent reading (ms)
11			 5 - writes completed
12			 6 - writes merged
13			 7 - sectors written
14			 8 - time spent writing (ms)
15			 9 - I/Os currently in progress
16			10 - time spent doing I/Os (ms)
17			11 - weighted time spent doing I/Os (ms)
18			For more details refer Documentation/iostats.txt
19	
20	
21	What:		/sys/block/<disk>/<part>/stat
22	Date:		February 2008
23	Contact:	Jerome Marchand <jmarchan@redhat.com>
24	Description:
25			The /sys/block/<disk>/<part>/stat files display the
26			I/O statistics of partition <part>. The format is the
27			same as the above-written /sys/block/<disk>/stat
28			format.
29	
30	
31	What:		/sys/block/<disk>/integrity/format
32	Date:		June 2008
33	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
34	Description:
35			Metadata format for integrity capable block device.
36			E.g. T10-DIF-TYPE1-CRC.
37	
38	
39	What:		/sys/block/<disk>/integrity/read_verify
40	Date:		June 2008
41	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
42	Description:
43			Indicates whether the block layer should verify the
44			integrity of read requests serviced by devices that
45			support sending integrity metadata.
46	
47	
48	What:		/sys/block/<disk>/integrity/tag_size
49	Date:		June 2008
50	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
51	Description:
52			Number of bytes of integrity tag space available per
53			512 bytes of data.
54	
55	
56	What:		/sys/block/<disk>/integrity/device_is_integrity_capable
57	Date:		July 2014
58	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
59	Description:
60			Indicates whether a storage device is capable of storing
61			integrity metadata. Set if the device is T10 PI-capable.
62	
63	What:		/sys/block/<disk>/integrity/protection_interval_bytes
64	Date:		July 2015
65	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
66	Description:
67			Describes the number of data bytes which are protected
68			by one integrity tuple. Typically the device's logical
69			block size.
70	
71	What:		/sys/block/<disk>/integrity/write_generate
72	Date:		June 2008
73	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
74	Description:
75			Indicates whether the block layer should automatically
76			generate checksums for write requests bound for
77			devices that support receiving integrity metadata.
78	
79	What:		/sys/block/<disk>/alignment_offset
80	Date:		April 2009
81	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
82	Description:
83			Storage devices may report a physical block size that is
84			bigger than the logical block size (for instance a drive
85			with 4KB physical sectors exposing 512-byte logical
86			blocks to the operating system).  This parameter
87			indicates how many bytes the beginning of the device is
88			offset from the disk's natural alignment.
89	
90	What:		/sys/block/<disk>/<partition>/alignment_offset
91	Date:		April 2009
92	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
93	Description:
94			Storage devices may report a physical block size that is
95			bigger than the logical block size (for instance a drive
96			with 4KB physical sectors exposing 512-byte logical
97			blocks to the operating system).  This parameter
98			indicates how many bytes the beginning of the partition
99			is offset from the disk's natural alignment.
100	
101	What:		/sys/block/<disk>/queue/logical_block_size
102	Date:		May 2009
103	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
104	Description:
105			This is the smallest unit the storage device can
106			address.  It is typically 512 bytes.
107	
108	What:		/sys/block/<disk>/queue/physical_block_size
109	Date:		May 2009
110	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
111	Description:
112			This is the smallest unit a physical storage device can
113			write atomically.  It is usually the same as the logical
114			block size but may be bigger.  One example is SATA
115			drives with 4KB sectors that expose a 512-byte logical
116			block size to the operating system.  For stacked block
117			devices the physical_block_size variable contains the
118			maximum physical_block_size of the component devices.
119	
120	What:		/sys/block/<disk>/queue/minimum_io_size
121	Date:		April 2009
122	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
123	Description:
124			Storage devices may report a granularity or preferred
125			minimum I/O size which is the smallest request the
126			device can perform without incurring a performance
127			penalty.  For disk drives this is often the physical
128			block size.  For RAID arrays it is often the stripe
129			chunk size.  A properly aligned multiple of
130			minimum_io_size is the preferred request size for
131			workloads where a high number of I/O operations is
132			desired.
133	
134	What:		/sys/block/<disk>/queue/optimal_io_size
135	Date:		April 2009
136	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
137	Description:
138			Storage devices may report an optimal I/O size, which is
139			the device's preferred unit for sustained I/O.  This is
140			rarely reported for disk drives.  For RAID arrays it is
141			usually the stripe width or the internal track size.  A
142			properly aligned multiple of optimal_io_size is the
143			preferred request size for workloads where sustained
144			throughput is desired.  If no optimal I/O size is
145			reported this file contains 0.
146	
147	What:		/sys/block/<disk>/queue/nomerges
148	Date:		January 2010
149	Contact:
150	Description:
151			Standard I/O elevator operations include attempts to
152			merge contiguous I/Os. For known random I/O loads these
153			attempts will always fail and result in extra cycles
154			being spent in the kernel. This allows one to turn off
155			this behavior on one of two ways: When set to 1, complex
156			merge checks are disabled, but the simple one-shot merges
157			with the previous I/O request are enabled. When set to 2,
158			all merge tries are disabled. The default value is 0 -
159			which enables all types of merge tries.
160	
161	What:		/sys/block/<disk>/discard_alignment
162	Date:		May 2011
163	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
164	Description:
165			Devices that support discard functionality may
166			internally allocate space in units that are bigger than
167			the exported logical block size. The discard_alignment
168			parameter indicates how many bytes the beginning of the
169			device is offset from the internal allocation unit's
170			natural alignment.
171	
172	What:		/sys/block/<disk>/<partition>/discard_alignment
173	Date:		May 2011
174	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
175	Description:
176			Devices that support discard functionality may
177			internally allocate space in units that are bigger than
178			the exported logical block size. The discard_alignment
179			parameter indicates how many bytes the beginning of the
180			partition is offset from the internal allocation unit's
181			natural alignment.
182	
183	What:		/sys/block/<disk>/queue/discard_granularity
184	Date:		May 2011
185	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
186	Description:
187			Devices that support discard functionality may
188			internally allocate space using units that are bigger
189			than the logical block size. The discard_granularity
190			parameter indicates the size of the internal allocation
191			unit in bytes if reported by the device. Otherwise the
192			discard_granularity will be set to match the device's
193			physical block size. A discard_granularity of 0 means
194			that the device does not support discard functionality.
195	
196	What:		/sys/block/<disk>/queue/discard_max_bytes
197	Date:		May 2011
198	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
199	Description:
200			Devices that support discard functionality may have
201			internal limits on the number of bytes that can be
202			trimmed or unmapped in a single operation. Some storage
203			protocols also have inherent limits on the number of
204			blocks that can be described in a single command. The
205			discard_max_bytes parameter is set by the device driver
206			to the maximum number of bytes that can be discarded in
207			a single operation. Discard requests issued to the
208			device must not exceed this limit. A discard_max_bytes
209			value of 0 means that the device does not support
210			discard functionality.
211	
212	What:		/sys/block/<disk>/queue/discard_zeroes_data
213	Date:		May 2011
214	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
215	Description:
216			Will always return 0.  Don't rely on any specific behavior
217			for discards, and don't read this file.
218	
219	What:		/sys/block/<disk>/queue/write_same_max_bytes
220	Date:		January 2012
221	Contact:	Martin K. Petersen <martin.petersen@oracle.com>
222	Description:
223			Some devices support a write same operation in which a
224			single data block can be written to a range of several
225			contiguous blocks on storage. This can be used to wipe
226			areas on disk or to initialize drives in a RAID
227			configuration. write_same_max_bytes indicates how many
228			bytes can be written in a single write same command. If
229			write_same_max_bytes is 0, write same is not supported
230			by the device.
231	
232	What:		/sys/block/<disk>/queue/write_zeroes_max_bytes
233	Date:		November 2016
234	Contact:	Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
235	Description:
236			Devices that support write zeroes operation in which a
237			single request can be issued to zero out the range of
238			contiguous blocks on storage without having any payload
239			in the request. This can be used to optimize writing zeroes
240			to the devices. write_zeroes_max_bytes indicates how many
241			bytes can be written in a single write zeroes command. If
242			write_zeroes_max_bytes is 0, write zeroes is not supported
243			by the device.
244	
245	What:		/sys/block/<disk>/queue/zoned
246	Date:		September 2016
247	Contact:	Damien Le Moal <damien.lemoal@hgst.com>
248	Description:
249			zoned indicates if the device is a zoned block device
250			and the zone model of the device if it is indeed zoned.
251			The possible values indicated by zoned are "none" for
252			regular block devices and "host-aware" or "host-managed"
253			for zoned block devices. The characteristics of
254			host-aware and host-managed zoned block devices are
255			described in the ZBC (Zoned Block Commands) and ZAC
256			(Zoned Device ATA Command Set) standards. These standards
257			also define the "drive-managed" zone model. However,
258			since drive-managed zoned block devices do not support
259			zone commands, they will be treated as regular block
260			devices and zoned will report "none".
261	
262	What:		/sys/block/<disk>/queue/chunk_sectors
263	Date:		September 2016
264	Contact:	Hannes Reinecke <hare@suse.com>
265	Description:
266			chunk_sectors has different meaning depending on the type
267			of the disk. For a RAID device (dm-raid), chunk_sectors
268			indicates the size in 512B sectors of the RAID volume
269			stripe segment. For a zoned block device, either
270			host-aware or host-managed, chunk_sectors indicates the
271			size of 512B sectors of the zones of the device, with
272			the eventual exception of the last zone of the device
273			which may be smaller.
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