[DRBD-user] drbdadm verify speed

J. Ryan Earl oss at jryanearl.us
Wed Oct 20 03:26:08 CEST 2010


On Tue, Oct 19, 2010 at 1:35 PM, Ravi Kanth <raveeknth at gmail.com> wrote:

> I am trying to use drbdadm verify resources and I can only get 60Mbps data
> rate. I am using infiniband and my syncer rate is 500Mbps.
>

InfiniBand doesn't matter, you'd get the same verification performance on a
GigE network as you are CPU limited; single-thread limited to be precise.
 You need a faster CPU or a dedicated checksum engine such as the CRC32C
implementation in the newer 32nm Intel processors with a sufficiently new
revision of the kernel: http://lwn.net/Articles/292984/

Is there any setting that I can change for the verification to happen at the
> full bandwidth speed? I want to use the full bandwidth for verification.
>

You can try different checksum algorithms.  The bandwidth used by the
checksum verify is a small fraction of the reported checksumming speed.
 Unfortunately the verify requires a checksumming algorithm at the moment,
in your case where bandwidth between hosts is gratuitous, it would be more
efficient to NOT calculate checksums at all and just compare raw data.  To
my knowledge, DRBD does not support this currently.

-JR
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