How can I pinpoint the I/O hogs in my systems?

How can I pinpoint the I/O hogs in my systems?

I'm looking for commands that pinpoint and check a process that is generating a high disk I/O (input/output) read.

What would that command be in Solaris 8? What would it be in Linux?

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If you had said CPU or disk, that question would be very easy. Variations of the ps command could give you what you need.

I/O is much trickier! You'll need to do some work here -- there is no one magic command, though I'll mention a neat one at the end.

I like to try a variation of ps, iostat and lsof to determine what is eating up my I/O resources. You may need to download this utility from a site like http://www.stokely.com/unix.sysadm.resources/shareware.www.html.

iostat will give you a sense of what disks are busy and lsof will tell you what files are open at a given time and the placement of the files by filesystems and/or directory. Variations of the ps command will help you identify the top running processes on your system.

Did I say top? If your system does not come with it already, you can also get a copy of TOP, available for Solaris and Linux, that will also identify the top running processes on your system. From there, with a little more work, you should be able to find the I/O hogs.

This was first published in May 2003