Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
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. 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.