[DRBD-user] Speeding up sync rate on fast links and storage

Gennadiy Nerubayev parakie at gmail.com
Fri Dec 19 15:24:32 CET 2008

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, Dec 18, 2008 at 1:50 PM, Lars Ellenberg
<lars.ellenberg at linbit.com>wrote:

>
> try and you'll find out. if you allow more CPUs,
> try the drbd cpu-mask setting again.
>
> just for the record, iirc, I have benchmarked Connected DRBD streaming
> writes at ~600 MByte/sec in our lab with 10GbE as well as Dolphin
> Interconnect.  so the drbd code should be able to handle this.
>

Hmm. Just moving the interrupts didn't help, so I upgraded the kernel to the
current on kernel.org - prior to this I was using the stock RHEL 5.2 kernel.
The interesting thing after the upgrade is that the interrupts were now
spread out evenly between both cores, and amongst the tweaks that you've
mentioned, sndbuf-size 0 now had a positive effect, improving the
performance to ~380-390MB/s average on both IPoIB and 10Gbe. The odd thing
is that I see the sync rate spike sometimes (the first number) upwards to
700MB/s, so it's fluctuating a lot for whatever reason, and only averaging
the aforementioned 380-390.

What sort of kernel/cpu/memory configuration allowed you to get that 600MB/s
number?

Thanks,

-Gennadiy
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