[CentOS] DRBD very slow....

Coert Waagmeester

lgroups at waagmeester.co.za
Thu Jul 23 07:51:18 UTC 2009


On Wed, 2009-07-22 at 18:16 -0700, Ian Forde wrote:
> 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...
> 
> 	-I

I occasionally do migration from one dom0 to the other

I do not have clustered file sytems, so I make sure that two are only
primary during the migration.

I have no automation yet, I do it all manually to be sure.

I only have one syncer defenition, and according to the drbd manual that
is the rate for full resyncs?
> 
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