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drtanz
Joined: 19 Jul 2011
Posts: 24
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| Posted: Sat Oct 29, 2011 1:29 am Post subject: Reducing Disk IO rate |
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Hi I'm getting frequent messages that my Linode is having a lot of disk IO. How can I analyse this with a view to reducing it if necessary?
Typical message I get via email:
Your Linode, my-VPS, has exceeded the notification threshold (1000) for disk io rate by averaging 1442.34 for the last 2 hours. |
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Emufarmers
Joined: 07 Jan 2010
Posts: 19
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| Posted: Sat Oct 29, 2011 8:42 pm Post subject: |
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| You want to figure out what your server is doing when these messages are generated. If it's just, say, that your weekly backup is running, you probably don't have anything to worry about. |
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drtanz
Joined: 19 Jul 2011
Posts: 24
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| Posted: Sun Oct 30, 2011 2:24 am Post subject: |
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| How can I view that? |
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Guspaz
Joined: 26 May 2009
Posts: 1150
Location: Montreal, QC
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| Posted: Mon Oct 31, 2011 9:28 am Post subject: |
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| Try iotop during a period of high IO. |
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ahmadzz
Joined: 18 Feb 2012
Posts: 1
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| Posted: Sat Feb 18, 2012 2:50 am Post subject: |
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| I am running CentOS 5.5 and I am unable to install iotop on it. Please help |
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umdenken
Joined: 11 Aug 2004
Posts: 31
Location: Spokane, WA
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| Posted: Fri Mar 30, 2012 5:46 am Post subject: Wondering about the default 1000 IO Ops/sec default |
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The CPU usage and transfer quota are measured in percent, and so they make some kind of cognitive sense.
But the 1000 ops/sec doesn't have a meaning without context. Is that a lot? Or, busy but not overwhelmed? |
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Nuvini
Joined: 17 Feb 2012
Posts: 39
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| Posted: Fri Mar 30, 2012 9:05 am Post subject: |
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My cronjob consumes ~30K OPS - it's not like you're almost at your limit, it'll manage.
To be nice for the other people on your physical node it'll be good to watch with iotop though, to see what's causing it. |
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Guspaz
Joined: 26 May 2009
Posts: 1150
Location: Montreal, QC
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| Posted: Tue Apr 17, 2012 12:47 pm Post subject: Re: Wondering about the default 1000 IO Ops/sec default |
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umdenken wrote: The CPU usage and transfer quota are measured in percent, and so they make some kind of cognitive sense.
But the 1000 ops/sec doesn't have a meaning without context. Is that a lot? Or, busy but not overwhelmed?
Unfortunately, you can't transfer IOPS into a useful percentage since there are so many factors that can determine the max IOPS. Read versus write, sequential versus random, 4KB versus 32KB, etc. |
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