Re: poor write performance

[Wolfgang Hennerbichler <wolfgang.hennerbichler@risc-software.at>]

Hi James,

This is just pure speculation, but can you assure that the bonding works
correctly? Maybe you have issues there. I have seen a lot of incorrectly
configured bonding throughout my life as unix admin.

Maybe this could help you a little:
http://www.wogri.at/Port-Channeling-802-3ad.338.0.html

On 04/18/2013 01:46 PM, James Harper wrote:
> I'm doing some basic testing so I'm not really fussed about poor performance, but my write performance appears to be so bad I think I'm doing something wrong.
> 
> Using dd to test gives me kbytes/second for write performance for 4kb block sizes, while read performance is acceptable (for testing at least). For dd I'm using iflag=direct for read and oflag=direct for write testing.
> 
> My setup, approximately, is:
> 
> Two OSD's
> . 1 x 7200RPM SATA disk each
> . 2 x gigabit cluster network interfaces each in a bonded configuration directly attached (osd to osd, no switch)
> . 1 x gigabit public network
> . journal on another spindle
> 
> Three MON's
> . 1 each on the OSD's
> . 1 on another server, which is also the one used for testing performance
> 
> I'm using debian packages from ceph which are version 0.56.4
> 
> For comparison, my existing production storage is 2 servers running DRBD with iSCSI to the initiators which run Xen on top of a (C)LVM volumes on top of the iSCSI. Performance not spectacular but acceptable. The servers in question are the same specs as the servers I'm testing on.
> 
> Where should I start looking for performance problems? I've tried running some of the benchmark stuff in the documentation but I haven't gotten very far...
> 
> Thanks
> 
> James
> 
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-- 
DI (FH) Wolfgang Hennerbichler
Software Development
Unit Advanced Computing Technologies
RISC Software GmbH
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