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 Post subject: High disk I/O rate
PostPosted: Sun May 30, 2010 1:14 pm 
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Junior Member

Joined: Mon May 24, 2010 6:39 pm
Posts: 20
Hello,

I am wondering how I can tell what is using up all the disk I/O on my linode. I have been receiving emails about a high I/O rate and can't figure out why.

Quote:
has exceeded the notification threshold (1000) for disk io rate by averaging 6776.14 for the last 2 hours


It seems way to high for the time period these occur (overnight during slow usage hours).

Is there any command I could run to tell what is using the current disk I/O? I could easily set that up to run as a cron during these problematic hours and see if I can capture anything useful.


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 Post subject:
PostPosted: Sun May 30, 2010 1:31 pm 
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Senior Member

Joined: Fri May 02, 2008 8:44 pm
Posts: 1121
iotop might do the job.

By the way, do you have any disk-intensive cron jobs scheduled in the night? Such as backups, log analysis, etc.?


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 Post subject:
PostPosted: Sun May 30, 2010 4:43 pm 
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Junior Member

Joined: Mon May 24, 2010 6:39 pm
Posts: 20
I haven't configured any cron tasks yet. I am currently pulling backups weekly via a ssh (ssh key) remote machine. My issues are nightly.

iotop looks like it may do the job. I should be able to setup a task to run for an entire hour every second and dump the I/O usage.

As for running crons, it is default for a ubuntu 10.4 server.

Quote:
root@server:~# ls /etc/cron.*/
/etc/cron.d/:
nsd3 php5

/etc/cron.daily/:
apache2 apt aptitude bsdmainutils dpkg locate logrotate man-db ntp popularity-contest standard

/etc/cron.hourly/:

/etc/cron.monthly/:
standard

/etc/cron.weekly/:
man-db


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 Post subject:
PostPosted: Mon May 31, 2010 8:18 am 
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Senior Member

Joined: Sun Mar 07, 2010 7:47 pm
Posts: 1970
Website: http://www.rwky.net
Location: Earth
Does the io load time match the logrotate time? That can chew up a lot of IO.


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 Post subject:
PostPosted: Mon May 31, 2010 2:51 pm 
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Senior Newbie

Joined: Wed Jan 20, 2010 6:13 am
Posts: 6
Disable the cronjob for locate. That sweeps the file system nightly to build an index of where files are located.


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 Post subject:
PostPosted: Mon May 31, 2010 6:43 pm 
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Junior Member

Joined: Mon May 24, 2010 6:39 pm
Posts: 20
Ahh, locate does make sense since I don't get the emails every night. Now that I think about it, I usually get them after I have been adding, removing or updating software.


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