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For following SSD disk, await time is high but %util is less.

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
dm-3              0.00     0.00  132.00 2272.00   892.00 100244.00    84.14  1111.70  658.36    5.00  696.32   0.20  49.20

%util is ((r/s + w/s) * svctm/1000)*100 and util represents percentage of time device spent in servicing requests. So, ~50% util is not high.

On the other hand, await time is pretty high. Tasks actual await time in the queue is "await - svctm" i.e. (658.36 - 0.20)*100/658.36, which is close to 100%. That means that tasks are spending most of time waiting in the queue.

If util is low but await time is high, is disk being utilized properly? Which one of these two metrics is more reliable for SSDs?

Tarun Kumar
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1 Answers1

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Screenshot shows your write wait time is high. SSD write generally tend to get slow after usage as they fill up and because of many other reasons like,

  1. Compatibility issues - Check compatibility with your HW
  2. If you clone the partition from HDD to SSD
  3. If TRIM is not enabled
  4. If its not initialized with zeros/ones
  5. If its behind any IOcontroller then IOcontroller itself might be slow

Check what all scenarios fits you and perform cleanup/initialization once and see if it resolves the issue. For compatibility issues, you might need to contact support team.

Nachiket Kate
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