Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Apr 6, 2006, at 1:35 AM, Michael Paesold wrote: > Ben wrote: >> For what it's worth, I'm doing exactly what you're looking to do >> right now with a whopping 7 DRBD devices. My write performance >> stinks - I can only sync at 4MB/sec before a CPU core becomes >> entirely busy in IO wait - but I suspect that's due to some >> misconfiguration, and haven't had much time to look into it. > > Thanks for the bit of information. > > 4MB/sec initial re-sync? Or 4MB/sec write performance in dom0 or in > domU? If its write performance in domU, you should look into > scheduling configuration. Both resync and steady-state write performance. Unfortunately I don't have any drbd resources mounted in my dom0 domains, but scp claims sustained write performance from one dom0 to another is around 25MB/s over my gigabit link. More interestingly, I do have a domU that isn't backed by DRBD, and it also only sees about 4MB/s write speeds. So I suspect my slowness has something to do with Xen, and not DRBD. > See for example this thread: > http://lists.xensource.com/archives/html/xen-users/2006-04/ > msg00115.html > Doing something like the mentioned 'xm sched-sedf 0 0 0 0 1 1' > could help. Alas, this did not help, but at least it gives me a place to look for more information. >> Other than the write performance, using DRBD and xen with >> heartbeat is really, really cool. > > Did you also try with less drbd devices and measure performance? Nope. I suspect that drbd is capable of far more than my piddling little usage scenario, and I suspect that my performance issues have nothing at all do to it. I don't need more than I've configured right now (or rather I need more RAM before I configure more domUs) so I haven't tested with anything larger.