[CentOS] DRBD very slow....

Thu Jul 23 01:16:06 UTC 2009
Ian Forde <ian at duckland.org>

On Wed, 2009-07-22 at 11:16 +0200, Coert Waagmeester wrote:
> The highest speed I can get through that link with drbd is 11 MB/sec
> (megabytes)

Not good...

> But if I copy a 1 gig file over that link I get 110 MB/sec.

That tells me that the network connection is fine.  The issue is at a
higher layer...

> Why is DRBD so slow? 

Let's see...

> common {
>   protocol C;
>   syncer { rate 80M; }
>   net {
>     allow-two-primaries;
>   }
> }

You want allow-two-primaries?  That implies that you're using something
like ocfs2, but that's probably immaterial to the discussion... Here's a
question - do you have another syncer statement in the resource
definition that's set to a lower number?  That would definitely throttle
the sync rate...