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On my Debian VPS, I am getting peaks of IO wait, which blocks my server for a few minutes. On the screenshot, you can see the Idle (green) which suddenly drops for IOwait (pink), which eventually blocks even the logging process (white stripe).Processor time

There is nothing strange happening on the machine (as you can see, most of the time, the machine is waiting) and the system resources are free (800 MB of RAM is unused).

I am worried that this is actually a problem of my VPS provider, but I don't know how to prove that.

Is there a way to find which can be causing this?

Thanks!

EDIT:

What can be the other small peaks, which are repeating probably every 5 minutes? How can I find how they are caused?

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Is it regular? How frequent? Anything in /var/log during the hangs? Does it coincide with and cron jobs? Install iotop and run iotop -Pbto > /tmp/io.log. Leave it running through one of those hangs and check the file to see heavy users. Please add any items of interest to your original post. –  SmallClanger Jun 14 '12 at 7:09
    
I usually find about this few minutes too late - is there a way to log these automatically once this start happening? –  Vojtěch Jun 14 '12 at 8:06
    
It is completely irregular and there are no cron jobs. I am the only user of the VPS. –  Vojtěch Jun 14 '12 at 8:16
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Start that iotop command now and leave it running. Wait until one of those spikes and then you can look back at the file /tmp/io.log and match up the timestamps with the period you're interested in. You should be able to see high I/O usage processes, if there are any. –  SmallClanger Jun 14 '12 at 12:20
    
It seems that nothing is happening with my application - iotop and top aren't showing any problems with my application. So I suppose it must be the VPS. –  Vojtěch Jun 17 '12 at 8:00
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1 Answer 1

Yes,

this behaviour look slike some other VM on the same physical host i susing up all bandwidth. Another explenation could be that your VM is just migrated over to another physical host, but this only your VM provider can answer...

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Will check with the provider. –  Vojtěch Jun 14 '12 at 8:06
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