1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
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.
|
