[CentOS] Extremely slow disk transfers with SATA disks

Peter Kjellström cap at nsc.liu.se
Thu Mar 23 15:54:44 UTC 2006


On Thursday 23 March 2006 15:37, Vanja Hrustic wrote:
> I have installed CentOS 4.2, recently, on new computer.
>
> Everything seemed to work fine.
>
> However, we've found out that disk transfers are incredibly slow, and I
> just can't figure out what to do in order to fix it.
>
> Computer is now running CentOS 4.3 (updated it 1 hour ago), and same
> thing is still present. I hoped kernel upgrade might fix it, but it
> didn't.

Very interesting, you do have working sata drivers (your device is /dev/sd*) 
and your hdparm -t gives expected number and yet you see really bad 
performance... wow.

Have you tried to figure out if it's reading or writing or both that suck? try 
this:

time dd if=/dev/zero of=testfile bs=1M count=1000

time dd if=testfile of=/dev/null bs=1M

If you have 1 gig ram or more adjust count...

/Peter

-- 
------------------------------------------------------------
  Peter Kjellström               | E-mail: cap at nsc.liu.se
  National Supercomputer Centre  |
  Sweden                         | http://www.nsc.liu.se
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