[Gllug] what is causing disk activity ?

[Luke Dudney]

On 20/11/08 12:26, 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
> sda              34.80         0.00       550.40          0       2752
> sdb              35.00         0.00       552.00          0       2760
> sdc               0.00         0.00         0.00          0          0
> md1              66.80         0.00       534.40          0       2672
> md0               0.00         0.00         0.00          0          0
> dm-0              5.20         0.00        41.60          0        208
> dm-1              0.00         0.00         0.00          0          0
> dm-2              0.00         0.00         0.00          0          0
> dm-3              0.00         0.00         0.00          0          0
> dm-4             61.40         0.00       491.20          0       2456
> dm-5              0.00         0.00         0.00          0          0
> dm-6              0.00         0.00         0.00          0          0
> dm-7              0.00         0.00         0.00          0          0
> dm-8              0.00         0.00         0.00          0          0
> dm-9              0.00         0.00         0.00          0          0
>
>
>   
All of that output refers to stats since boot. For real-time info try 
"iostat -x 5" and wait 5 seconds for the second lot of output

First thing to check would be to see if any processes are blocking on IO:

while true; do ps auwx |awk '$8 ~ /D/'; sleep 1; done

Cheers
Luke


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