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My server has been steady at about 2-3%, but today the CPU usage has raised to about 25%

When I run top in command line this is what I see.. user is still low about 1.3% and the same with system about 1.2% but then I look at wa.. 16.1% !?

What is wa and why is it suddenly so high?!

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clarkk
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1 Answers1

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According to the man page, wa is:

wa  --  iowait
Amount of time the CPU has been waiting for I/O to complete.
ricksebak
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  • Could you explain what it is – clarkk Jan 30 '14 at 15:53
  • The CPU is waiting for the disk to give it some data to work on. You should look into what the disk is doing. A more in depth answer is here, including tools that can be used to look into what the disk is doing: http://serverfault.com/questions/12679/can-anyone-explain-precisely-what-iowait-is – ricksebak Jan 30 '14 at 16:06
  • I don't think it is only disk, but any IO device which blocks a process from continuing. – ZeissS Jan 31 '14 at 17:34