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What is the definition of "Average Read Time" and "Average Write Time" for a LUN?
What is the definition of "Average Read Time" and "Average Write Time" for a LUN?
When calling the getlun command with the -readtime and -writetime flag, the documentation says this (Command Line Interface Reference for Block):
-readtime
Returns the cumulative read time in microseconds.
-writetime
Returns the cumulative write time in microseconds.
There is even a sample output:
naviseccli -h ss1_spa getlun 0 -readtime -writetime
Cumulative Read Time (microseconds): 87937
Cumulative Write Time (microseconds): 0
However, when running the command, I do not get the same output. I get an "Average" instead of a cumulative:
Average Read Time: 895296858
Average Write Time: 655934380
Does anybody knows the definition of those average values in this context?
Thanks,
Laurent.
kelleg
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April 21st, 2016 14:00
I believe those numbers are the total time for all the reads in a period of time. I believe the counters are 32-bit, so they would roll over after a certain amount of time. Analyzer uses these when calculating values for the LUN.
glen
Laurent_1
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April 22nd, 2016 08:00
Hi Glen,
What I'm trying to find is a defintiion. How is this value computed, and what is the unit. Microseconds? milliseconds? 100 ms? So far I have always assumed microseconds because the doc shows the output to be "cumulative time (microseconds)" but the output I see ("average read time") doesn't match the documentation.
Laurent.
kelleg
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April 25th, 2016 13:00
Are you running this against a Pool LUN or a raid group LUN? Found a note in the CLI guide:
If the target LUN is a pool LUN, we recommend that you use the storagepool -list command (see
storagepool -list on page 535) instead of the getlun command to return information about the pool
LUN.
glen
kelleg
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April 25th, 2016 13:00
What version of Flare is running on the array?
glen
Laurent_1
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April 25th, 2016 13:00
The Flare version is 05.32.000.5.215
Laurent_1
30 Posts
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April 25th, 2016 13:00
Raid group LUN. I know that getting performance data about pool LUNs from the CLI needs to be a bit different but here I'm only worried about raid group LUNs.
kelleg
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April 26th, 2016 14:00
As far as I can determine the information in the CLI guide is accurate - the times are in microseconds.
glen