Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Tuesday 14 October 2008 23:17, Lars Marowsky-Bree wrote: > 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. I see. I used this exact command from the webinar, assuming it was a good way to test performance. > So at least these parameters are far from sane - bs=16384 oflag=fsync > might provide better performance. I get about 1.3 MB/sec when using these values :-s > 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). I indeed use internal meta-data. There is somewhat of a problem in using external meta-data since I have no disk left. I could reconfigure the RAID-5 and dedicate a virtual disk to this, but would this enhance performance? > > 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 also use OES2, which doesn't work with SP2 I'm told. But I could always extract the 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. OK, will try that then! Thank you!!! Bart > Regards, > Lars