Re: Raid1: sdb has a lot mor work then sda

[Daniel Spannbauer <ds@marco.de>]

Hello,

here is a screendump of a atop -dD in such a situation.

Regards

Daniel




Am 04/24/2012 05:00 PM, schrieb Roberto Spadim:
> it´s a read, a write, or both operation?
> about load i think it´s a very big read (sdb) with a very low write (sda)
> the disk balance on raid1 is based on nearest (current position - next
> read position) disk
> on a sequencial read only one disk is better used
> 
> i checked that raid1 'have this problem' but it´s a hardware limit, i
> didn´t found a solution, maybe others friends can found
> 
> Em 24 de abril de 2012 11:46, Daniel Spannbauer <ds@marco.de
> <mailto:ds@marco.de>> escreveu:
> 
>     Hello,
> 
>     at the moment I'm trying to find a bottleneck on my lamp-server with
>     opensuse 11.4 (Kernel 2.6.37.6)
> 
>     Sometimes the system has a very poor performance because of a high
>     io-wait.
>     If I watch the systems disk-access with "atop -dD" I can see that sda is
>     the most of the time at a load of 10%, sdb sometimes is at 100% or
>     higher at the same time.
> 
>     In my opinion in a Raid1-System both disk should have nearly the
>     same load.
> 
>     Or may I wrong whis this?
> 
>     Both harddisks where changed 3 Weeks ago, /proc/mdstat shows that the
>     rebuild was successfull and the array is functional. Today I've changed
>     th SATA-Cable and the Port on the Maindboard of sdb, but the behaviour
>     is still the same. Both disks passed the extended smart-self-test.
> 
>     Any ideas about that?
> 
>     Regards
> 
>     Daniel
> 
> 
> 
>     --
>     Daniel Spannbauer                         Software Entwicklung
>     marco Systemanalyse und Entwicklung GmbH  Tel   +49 8333 9233-27
>     <tel:%2B49%208333%209233-27> Fax -11
>     Rechbergstr. 4 - 6, D 87727 Babenhausen   Mobil +49 171 4033220
>     <tel:%2B49%20171%204033220>
>     http://www.marco.de/                      Email ds@marco.de
>     <mailto:ds@marco.de>
>     Geschäftsführer Martin Reuter             HRB 171775 Amtsgericht München
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> 
> 
> 
> -- 
> Roberto Spadim
> Spadim Technology / SPAEmpresarial


-- 
Daniel Spannbauer                         Software Entwicklung
marco Systemanalyse und Entwicklung GmbH  Tel   +49 8333 9233-27 Fax -11
Rechbergstr. 4 - 6, D 87727 Babenhausen   Mobil +49 171 4033220
http://www.marco.de/                      Email ds@marco.de
Geschäftsführer Martin Reuter             HRB 171775 Amtsgericht München
--
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