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Displaying posts with tag: iowait (reset)

Don’t play with innodb_io_capacity! (with standard HDDs)
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A beautiful picture is sometimes better than words :

With standard HDDs (here in RAID 10), the innodb_io_capacity variable may have non expected effects.

You can see on this picture the result of a test on one of my server with only the replication thread activated. The value of the innodb_io_capacity variable was the single modification during the period.

So, don’t touch this parameter without a strong reason…
(Of course 30000 was a bit snooty)

[MAJ 2013-01-08] : I know 30k is a too high value for innodb_io_capacity, I used this value to make the graphe really eloquent.
Read this excellent post from Chris for more details : 


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Does "mpstat" can replace "vmstat" ?
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I prefer to say right now, the answer is no !
However, mpstat can provide a minimum service to show essentials information about your CPU usage :

Show usage for all CPU (every 1s) : mpstat 1

Show usage for CPU number 2 (every 1s) : mpstat -P 2 1

It’s possible to retrieve CPU load (user/sys) and IO waits via a simple interface.
And I like the opportunity to focus on a single CPU. It can be a usefull tool for monitoring and scripting.

But there isn’t any information about the run queue processes and this is the bad news here !



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Showing entries 1 to 2

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