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imported>ThorstenStaerk |
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| − | iostat is a [[program]] that shows how many I/O operations happen in a specified timeframe.
| + | #REDIRECT [[ConVersIOn]] |
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| − | = Install it =
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| − | To install iostat, install the package sysstat. For example with SUSE Linux you [[open a console]] and enter:
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| − | yast -i sysstat
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| − | | |
| − | = Run it =
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| − | Just call IOstat plus the time interval in seconds:
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| − | <pre>
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| − | # iostat 10 | |
| − | Linux 2.6.34.7-0.5-desktop (tweedleburg) 12/11/10 _x86_64_ (8 CPU)
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| − | avg-cpu: %user %nice %system %iowait %steal %idle
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| − | 0.67 0.00 0.17 0.07 0.00 99.09
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| − | Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
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| − | sdb 1.35 5.76 28.55 1387011 6870465
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| − | sda 1.35 5.56 28.55 1337701 6870465
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| − | md126 4.26 11.32 28.38 2723674 6830024
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| − | </pre>
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| − | You will get a new block every 10 seconds in this case.
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| − | | |
| − | Zoom in to one device, 1 second interval:
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| − | <pre>
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| − | # iostat -xmt 1 -d /dev/sda
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| − | Linux 2.6.34.7-0.7-desktop (tweedleburg) 03/03/11 _x86_64_ (8 CPU)
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| − | 03/03/11 08:46:33
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| − | Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
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| − | sda 0.03 1.63 0.06 0.72 0.00 0.01 26.56 0.08 108.28 4.64 0.36
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| − | 03/03/11 08:46:34
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| − | Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
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| − | sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
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| − | </pre>
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| − | | |
| − | == avgrq-sz ==
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| − | avgrq-sz is the average request size in 512 byte sectors. You can influence it with [[dd]]'s iflag/oflag parameter, for example:
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| − | dd if=/dev/dm-11 of=/dev/null iflag=direct bs=64K
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| − | Note there is a max block size under /sys/block/''device''/queue/max_sector_kb
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| − | | |
| − | = See also =
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| − | * [[diagnostics]]
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| − | * [[vmstat]]
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| − | * [[sar]]
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