Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Dec 20, 2007 3:05 AM, Lars Ellenberg <lars.ellenberg at linbit.com> wrote: > On Wed, Dec 19, 2007 at 04:41:37PM -0800, Art Age Software wrote: > > I have run some additional tests: > > > > 1) Disabled bonding on the network interfaces (both nodes). No > > significant change. > > > > 2) Changed the DRBD communication interface. Was using a direct > > crossover connection between the on-board NICs of the servers. I > > switched to Intel Gigabit NIC cards in both machines, connecting > > through a Gigabit switch. No significant change. > > > > 3) Ran a file copy from node1 to node2 via scp. Even with the > > additional overhead of scp, I get a solid 65 MB/sec. throughput. > > this is streaming. > completely different than what we measured below. > > > So, at this stage I have seemingly ruled out: > > > > 1) Slow IO subsystem (both machines measured and check out fine). > > > > 2) Bonding driver (additional latency) > > > > 3) On-board NICs (hardware/firmware problem) > > > > 4) Network copy speed. > > > > What's left? I'm stumped as to why DRBD can only do about 3.5 BM/sec. > > on this very fast hardware. > > doing one-by-one synchronous 4k writes, which are latency bound. > if you do streaming writes, it probably get up to your 65 MB/sec again. Ok, but we have tested that with and without DRBD by the dd command, right? So at this point, by all tests performed so far, it looks like DRBD is the bottleneck. What other tests can I perform that can say otherwise? > sorry, latency tuning can be complex, > and is not easily covered by "general advice". > > -- > : Lars Ellenberg http://www.linbit.com : > : DRBD/HA support and consulting sales at linbit.com : > : LINBIT Information Technologies GmbH Tel +43-1-8178292-0 : > : Vivenotgasse 48, A-1120 Vienna/Europe Fax +43-1-8178292-82 : > __ > please use the "List-Reply" function of your email client. > _______________________________________________ > > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user >