Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 2008-10-14T18:32:50, Bart Coninckx <bart.coninckx at telenet.be> wrote:
> Hi all,
>
> I previously posted about a sync going somewhat slow (managed to get it up to
> 18MB/sec).
> I figured this could be just the syncing, so I decided to do some performance
> tests as mentionned in the webinar.
>
> I used:
> dd if=/dev/zero of=/dev/drbd0 bs=1G count=1 oflag=direct
oflag=direct uses direct sync'ing (obviously), which means there's not
very much optimization going on. bs=1G also means that a huge memory
block is allocated and flushed.
So at least these parameters are far from sane - bs=16384 oflag=fsync
might provide better performance.
The next step might be to check whether you're using internal meta-data,
which also might not exactly perform very well (seek time issues).
> The server is a HP ML370 G5 with a 1TB RAID-5 setup. The controller used the
> cciss driver. DRBD is 0.7.22. OS is SLES 10 SP1. The network link is gigabit,
> full duplex, set to 1000 Mbit.
Of course, I am inclined to advise an upgrade to SP2, which might help
with a newer cciss driver ;-)
> I plan to enable write back cache, but I wonder if that is going to make THE
> difference.
If you're using internal metadata, that is going to make a huge
difference.
Regards,
Lars
--
Teamlead Kernel, SuSE Labs, Research and Development
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde