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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 | ||
56 | What: /sys/block/<disk>/integrity/write_generate | |
57 | Date: June 2008 | |
58 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
59 | Description: | |
60 | Indicates whether the block layer should automatically | |
61 | generate checksums for write requests bound for | |
62 | devices that support receiving integrity metadata. | |
c72758f3 MP |
63 | |
64 | What: /sys/block/<disk>/alignment_offset | |
65 | Date: April 2009 | |
66 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
67 | Description: | |
68 | Storage devices may report a physical block size that is | |
69 | bigger than the logical block size (for instance a drive | |
70 | with 4KB physical sectors exposing 512-byte logical | |
71 | blocks to the operating system). This parameter | |
72 | indicates how many bytes the beginning of the device is | |
73 | offset from the disk's natural alignment. | |
74 | ||
75 | What: /sys/block/<disk>/<partition>/alignment_offset | |
76 | Date: April 2009 | |
77 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
78 | Description: | |
79 | Storage devices may report a physical block size that is | |
80 | bigger than the logical block size (for instance a drive | |
81 | with 4KB physical sectors exposing 512-byte logical | |
82 | blocks to the operating system). This parameter | |
83 | indicates how many bytes the beginning of the partition | |
84 | is offset from the disk's natural alignment. | |
85 | ||
86 | What: /sys/block/<disk>/queue/logical_block_size | |
87 | Date: May 2009 | |
88 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
89 | Description: | |
90 | This is the smallest unit the storage device can | |
91 | address. It is typically 512 bytes. | |
92 | ||
93 | What: /sys/block/<disk>/queue/physical_block_size | |
94 | Date: May 2009 | |
95 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
96 | Description: | |
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97 | This is the smallest unit a physical storage device can |
98 | write atomically. It is usually the same as the logical | |
99 | block size but may be bigger. One example is SATA | |
100 | drives with 4KB sectors that expose a 512-byte logical | |
101 | block size to the operating system. For stacked block | |
102 | devices the physical_block_size variable contains the | |
103 | maximum physical_block_size of the component devices. | |
c72758f3 MP |
104 | |
105 | What: /sys/block/<disk>/queue/minimum_io_size | |
106 | Date: April 2009 | |
107 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
108 | Description: | |
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109 | Storage devices may report a granularity or preferred |
110 | minimum I/O size which is the smallest request the | |
111 | device can perform without incurring a performance | |
112 | penalty. For disk drives this is often the physical | |
113 | block size. For RAID arrays it is often the stripe | |
114 | chunk size. A properly aligned multiple of | |
115 | minimum_io_size is the preferred request size for | |
116 | workloads where a high number of I/O operations is | |
117 | desired. | |
c72758f3 MP |
118 | |
119 | What: /sys/block/<disk>/queue/optimal_io_size | |
120 | Date: April 2009 | |
121 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
122 | Description: | |
123 | Storage devices may report an optimal I/O size, which is | |
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124 | the device's preferred unit for sustained I/O. This is |
125 | rarely reported for disk drives. For RAID arrays it is | |
126 | usually the stripe width or the internal track size. A | |
127 | properly aligned multiple of optimal_io_size is the | |
128 | preferred request size for workloads where sustained | |
129 | throughput is desired. If no optimal I/O size is | |
130 | reported this file contains 0. | |
488991e2 AB |
131 | |
132 | What: /sys/block/<disk>/queue/nomerges | |
133 | Date: January 2010 | |
134 | Contact: | |
135 | Description: | |
136 | Standard I/O elevator operations include attempts to | |
137 | merge contiguous I/Os. For known random I/O loads these | |
138 | attempts will always fail and result in extra cycles | |
139 | being spent in the kernel. This allows one to turn off | |
140 | this behavior on one of two ways: When set to 1, complex | |
141 | merge checks are disabled, but the simple one-shot merges | |
142 | with the previous I/O request are enabled. When set to 2, | |
143 | all merge tries are disabled. The default value is 0 - | |
144 | which enables all types of merge tries. | |
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145 | |
146 | What: /sys/block/<disk>/discard_alignment | |
147 | Date: May 2011 | |
148 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
149 | Description: | |
150 | Devices that support discard functionality may | |
151 | internally allocate space in units that are bigger than | |
152 | the exported logical block size. The discard_alignment | |
153 | parameter indicates how many bytes the beginning of the | |
154 | device is offset from the internal allocation unit's | |
155 | natural alignment. | |
156 | ||
157 | What: /sys/block/<disk>/<partition>/discard_alignment | |
158 | Date: May 2011 | |
159 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
160 | Description: | |
161 | Devices that support discard functionality may | |
162 | internally allocate space in units that are bigger than | |
163 | the exported logical block size. The discard_alignment | |
164 | parameter indicates how many bytes the beginning of the | |
165 | partition is offset from the internal allocation unit's | |
166 | natural alignment. | |
167 | ||
168 | What: /sys/block/<disk>/queue/discard_granularity | |
169 | Date: May 2011 | |
170 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
171 | Description: | |
172 | Devices that support discard functionality may | |
173 | internally allocate space using units that are bigger | |
174 | than the logical block size. The discard_granularity | |
175 | parameter indicates the size of the internal allocation | |
176 | unit in bytes if reported by the device. Otherwise the | |
177 | discard_granularity will be set to match the device's | |
178 | physical block size. A discard_granularity of 0 means | |
179 | that the device does not support discard functionality. | |
180 | ||
181 | What: /sys/block/<disk>/queue/discard_max_bytes | |
182 | Date: May 2011 | |
183 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
184 | Description: | |
185 | Devices that support discard functionality may have | |
186 | internal limits on the number of bytes that can be | |
187 | trimmed or unmapped in a single operation. Some storage | |
188 | protocols also have inherent limits on the number of | |
189 | blocks that can be described in a single command. The | |
190 | discard_max_bytes parameter is set by the device driver | |
191 | to the maximum number of bytes that can be discarded in | |
192 | a single operation. Discard requests issued to the | |
193 | device must not exceed this limit. A discard_max_bytes | |
194 | value of 0 means that the device does not support | |
195 | discard functionality. | |
196 | ||
197 | What: /sys/block/<disk>/queue/discard_zeroes_data | |
198 | Date: May 2011 | |
199 | Contact: Martin K. Petersen <martin.petersen@oracle.com> | |
200 | Description: | |
201 | Devices that support discard functionality may return | |
202 | stale or random data when a previously discarded block | |
203 | is read back. This can cause problems if the filesystem | |
204 | expects discarded blocks to be explicitly cleared. If a | |
205 | device reports that it deterministically returns zeroes | |
206 | when a discarded area is read the discard_zeroes_data | |
207 | parameter will be set to one. Otherwise it will be 0 and | |
208 | the result of reading a discarded area is undefined. |