My disk often is utilized, but top (and htop, a custom replacement) show nothing suspicious.

Is there a way to sort processes by I/O (more specific: disk) utilization?

Found out using iotop that those strange processes are flush-8:16 and jbd2/sdb3-7. Seems to have to do with usual filesystem operations.

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    If I'm correct flush and jbd concerns the sync of the journal (FS metadata) to the disk. Which means you must have some processes either writing to the disk or reading a lot of data and you have the atime option on your mount. I don't recommend this because some software relies on it (mutt and I have heard one backup tool) but you can set your mount to relatime or even "better" noatime. The latter will completely stop updating the access time (which incures a disk write) each time a file is read. – Huygens Jul 27 '12 at 21:48

Have you tried iotop ?

You may need to install it before. Also, it depends on a kernel feature that may or may not enabled in your specific distribution.

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    Works on Mac OS X, too. Not sure that it is going to help with the problem at hand, though. – dmckee Mar 2 '10 at 16:27
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    wow. That's fantastic. 15+ years of admin work and I've never run into that. Thanks! – skarface Mar 2 '10 at 17:06
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    Root access needed, FYI. – Paul Draper Jan 24 '15 at 17:27

You might want to give atop a try. It seems to do a good job of letting you know what is going on.

  • Seems to be better than iotop because it also shows IO busy percent. – sorin Mar 18 '14 at 13:36
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    Also no root or suid needed. – Rolf Feb 25 '18 at 21:08

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