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Disk I/O Monitoring for Cent 5.6
Disk I/O Monitoring for Cent 5.6
Das Capitolin




msg:4352330
 5:10 am on Aug 17, 2011 (gmt 0)

For the past month my Cent 5.6 server has suffered random I/O spikes that last from several minutes to many hours. I'm struggling to find the ideal tool to help track down the culprit, and hope the users here can offer some suggestions.

I've got Webmin installed which tells me basic I/O usage in %, but stops short of pointing out process I/O usage. I've also installed Cacti, but it doesn't appear I can run down the problem with it either. Using the vmstat command (vmstat 1 10) tells me almost nothing useful.

Please offer some guidance.

 

phranque




msg:4352348
 6:41 am on Aug 17, 2011 (gmt 0)

perhaps iostat will provide the information you need.

Das Capitolin




msg:4352695
 2:34 pm on Aug 17, 2011 (gmt 0)

Thank you, but iostat (iostat -d -k -x) only shows me read/write activity on the disk. What I need is to see that information at a process level.

Das Capitolin




msg:4352697
 2:38 pm on Aug 17, 2011 (gmt 0)

sar -b produces roughly the same results, so it won't work either.

bakedjake




msg:4352699
 2:40 pm on Aug 17, 2011 (gmt 0)

block_dump is what you're looking for.

Be careful; only use it sparingly for short amounts of time as it generates massive (additional) disk activity.

Enable it with sysctl, then use /var/log/debug to find the culprit. Remember to disable it when you're done!

Das Capitolin




msg:4352710
 2:52 pm on Aug 17, 2011 (gmt 0)

This one looks like a winner, thank you!

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