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Commit | Line | Data |
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0e53c2be JM |
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: | |
af901ca1 | 7 | 1 - reads completed successfully |
0e53c2be JM |
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. | |
c1c72b59 MP |
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 | ||
3aec2f41 MP |
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 | ||
4c241d08 MP |
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. | |
3aec2f41 | 70 | |
c1c72b59 MP |
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. | |
c72758f3 MP |
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: | |
7e5f5fb0 MP |
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. | |
c72758f3 MP |
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: | |
7e5f5fb0 MP |
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. | |
c72758f3 MP |
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 | |
7e5f5fb0 MP |
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. | |
488991e2 AB |
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. | |
d70d0711 MP |
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 | Devices that support discard functionality may return | |
217 | stale or random data when a previously discarded block | |
218 | is read back. This can cause problems if the filesystem | |
219 | expects discarded blocks to be explicitly cleared. If a | |
220 | device reports that it deterministically returns zeroes | |
221 | when a discarded area is read the discard_zeroes_data | |
222 | parameter will be set to one. Otherwise it will be 0 and | |
223 | the result of reading a discarded area is undefined. | |
4363ac7c MP |
224 | |
225 | What: /sys/block/<disk>/queue/write_same_max_bytes | |
226 | Date: January 2012 | |
227 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
228 | Description: | |
229 | Some devices support a write same operation in which a | |
230 | single data block can be written to a range of several | |
231 | contiguous blocks on storage. This can be used to wipe | |
232 | areas on disk or to initialize drives in a RAID | |
233 | configuration. write_same_max_bytes indicates how many | |
234 | bytes can be written in a single write same command. If | |
235 | write_same_max_bytes is 0, write same is not supported | |
236 | by the device. | |
237 |