[Gllug] what is causing disk activity ?

[Kostas Georgiou]

On Thu, Nov 20, 2008 at 12:26:31PM +0000, Alain Williams wrote:

> The disk on my main-server/desktop seems to be continually chattering.
> What is causing it. I'm not really doing anything other than type stuff in
> emacs. So what is causing it ? Being paranoid I am wondering if I have been
> rooted.
> 
> Is there any way that I can relate the disc activity to processes ?
> 
> It is a Centos 5 based system.
> 
> 
> iostat output below (not the first block that contains totals since boot):
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            3.20    0.00    1.20    1.00    0.00   94.59
> 
> Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
...
> dm-4             61.40         0.00       491.20          0       2456
....

Finding out where dm-4 is mounted might give you enough hints to track
down the process. 

With a newer kernel you can use iotop to find out which process is
generating the IO but with Centos 5 you options are limited to using
/proc/sys/vm/block_dump and maybe blktrace might be able to give you the
list of processes generating IO (I mostly use it with seekwatcher so I
can't remember if the traces give you enough info for what you want).

Cheers,
Kostas Georgiou
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