Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
0.7.22 Reply-To: X-Mailer: anchor v0.0 X-No-CC: Please respect the setting of my Mail-Followup-To header Hi, I've recently upgraded a couple of machines we already had running DRBD 0.7.22 and previously the performance we were seeing seemed ok so I didn't do comprehensive tests. Now that the machines have been upgraded and are doing a bit more we are starting to notice the performance isn't quite what it should be. Briefly the systems are: Supermicro X7DBP 2 x Intel Xeon 5160 dual core @ 3GHz 4GB ECC DDR400 Adaptec 2020ZCR RAID card 2 x 147GB 15krpm SCSI drives 2 x 300GB 10krpm SCSI drives RHEL4ES 64bit on 2.6.9-67.0.7.ELsmp kernel DRBD 0.7.22 (which is the latest stable version that was available at the time the cluster was built) Each of the drives is only set up as a logical drive in the RAID card, and RAID1 is done in the software for each pair of drives. We have write-caching turned on for the 147GB drives. If I test write speed with something like 'time sync; time dd if=/dev/zero of=test bs=1G count=4; time sync' on a non-DRBD partition of the 147GB RAID, I see write speeds of about 53MB/s. If I perform the same test on a DRBD partition on the 147GB RAID that is disconnected, I'm seeing write speeds of about 38MB/s. To go down to about 70% of non-DRBD performance before we have even taken into account slowdowns due to the network is a very big performance hit. I'm also seeing similar results on the 300GB drives, but about 33% less performance overall again due to the drop in spindle speed. DRBD-connected speed is even worse but I'm holding off on persuing that until I have the disconnected speeds sorted out. Some other info: al-extents 601 meta-disk is internal (I know this represents a metadata write after only 2.3GB or so, but we see the same slow performance with smaller write sizes) comms over 1GbE NICs directly connected MTU of 9000 syncer rate 50M sndbuf-size 256K max-buffers 2048 max-epoch-size 2048 As I said, the network side probably needs attention as well but for the moment I need to address the large discrepancy between the non-DRBD and disconnected-DRBD speeds first. Any suggestions would be appreciated. -- Regards, Oliver Hookins