Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Thu, Nov 13, 2008 at 04:13:42PM +0100, Felix Zachlod wrote: > Hello Group! > > I have been trying to set up a drbd configuration with two storage servers > running under rpath Linux (openfiler). The Kernel version is 2.6.26. The > Systems are each running on a q-core Xeon processor, 4GB memory and have a > 16 channel icp raid controller with BBWC and are configured with raid 60 > underlying. Trying to write to a sample partition /dev/sdbX on each of the > machines will reach about 120MByte/s write performance which seems is poor > for a raid of 16 1TB SATA drives but okay that is not the point here. > > Trying > to write to the drbd1 device gives a performance of ~ 3MByte/s if both nodes > are online and ~8Mbyte if writing to the primary node where the secondary is > offline. > > I watched the webinar about performance tuning for drbd and tried > several options such as max-buffers, al-extents and no-disk-flushes which > all in all did not help at all. Performance increases with this tuning > parameters are not more than 10-15 percent whereby this might be measuring > inaccuracy too. as your controller cache has a working BBU, you can safely use "no-disk-flushes;" starting with drbd 8.2.7, you should then also say "no-disk-barriers;". verify that the settings are actually used with drbdsetup /dev/drbd0 show > Both machines are connected with two crossover cables and a balance-rr > bonding device which gives a throughput of ~ 210MByte/s using tcp. But the > fact that writing on a local disk is very slow using the drbd driver either > I think the fault has to found somewhere in the io-configuration. in that setup, I'd expect to be able to saturate your raid controller. > I tested performance using: > > dd if=/dev/zero of=/dev/drbd1 bs=512M count=1 > > giving me a performance of ~ 8Mbyte /s > > and > > dd if=/dev/zero of/dev/sdb3 bs=512M count=1 > > giving me a performance of ~ 110-120Mbyte/s > > (where drbd1 is pointing to /dev/sdb1 on each node). > > Read performance is not as bad as write performance so I get 230Mbyte/s vs > 125Mbyte/s (but its bad enough) does "oflag=direct" resp. "iflag=direct" change anything in those micro benchmarks? > > If anyone has a hint what to try next it would be greatly appreciated. > > > Thank you in advanced > With kind regards, Felix > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed