[CentOS] DRBD very slow....

On Mon, 2009-07-27 at 12:37 +0200, Coert Waagmeester wrote:
> On Mon, 2009-07-27 at 12:02 +0200, Alexander Dalloz wrote:
> > >
> > > On Mon, 2009-07-27 at 08:30 +0200, Coert Waagmeester wrote:
> > 
> > >> Hello Roman,
> > >>
> > >> I am running drbd 8.2.6 (the standard centos version)
> > 
> > 
> > Hi,
> > 
> > have you considered to test the drbd-8.3 packages?
> > 
> > http://bugs.centos.org/view.php?id=3598
> > 
> > http://dev.centos.org/centos/5/testing/{i386,x86_64}/RPMS/
> > 
> > Best regards
> > 
> > Alexander
> > 
> > 
> > 
> > _______________________________________________
> > CentOS mailing list
> > CentOS at centos.org
> > http://lists.centos.org/mailman/listinfo/centos
> 
> Thank you very much for this tip! It was one very obvious place where I
> did not look yet.
> 
> 
> Would it be necessary to still recompile it for the TCP_NODELAY and
> such?
> 
> I am just making sure, because
> http://www.nabble.com/Huge-latency-issue-with-8.2.6-td18947965.html
> makes it seem unnecessary.
> 
> Why do the repositories provide both DRBD 8.0.x and 8.2.6?
> 
> Thank you all again,
> Coert
> 
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos



Hello all,

Here is a status update....
_______________________________________________________________________________
on both hosts I now run from the testing repository:
# rpm -qa | grep drbd
drbd83-8.3.1-5.el5.centos
kmod-drbd83-xen-8.3.1-4.el5.centos
_______________________________________________________________________________
Here is my config (slightly condensed):
-----------------------------------------------------
global {
  usage-count yes;
}
common {
  protocol C;
  syncer { rate 50M; }
  net {
#        allow-two-primaries; }
         sndbuf-size 0; }
#  disk {no-disk-flushes;
#        no-md-flushes; }
  startup { wfc-timeout 0 ; }
}
resource xenfilesrv {
  device    /dev/drbd1;
  disk      /dev/vg0/xenfilesrv;
  meta-disk internal;

  on baldur.mydomain.local {
    address   10.99.99.1:7788;
  }
  on thor.mydomain.local {
    address   10.99.99.2:7788;
  }
}
resource xenfilesrvdata {
  device    /dev/drbd2;
  disk      /dev/vg0/xenfilesrvdata;
  meta-disk internal;

  on baldur.mydomain.local {
    address   10.99.99.1:7789;
  }
  on thor.mydomain.local {
    address   10.99.99.2:7789;
  }
}
_______________________________________________________________________________

xenfilesrv is a xen domU
in this domU i ran a dd with oflag direct:
---------------------------------------------------------
# dd if=/dev/zero of=1gig.file bs=1M count=1000 oflag=direct
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 147.997 seconds, 7.1 MB/s

Just before I ran the dd this popped up in the secondary hosts syslog:
----------------------------------------------------------------------
Jul 27 21:51:42 thor kernel: drbd2: Method to ensure write ordering:
flush
Jul 27 21:51:42 thor kernel: drbd1: Method to ensure write ordering:
flush


_______________________________________________________________________________

What more can I try?

To be quite honest, I have no idea what to do with/ where to find the
TCP_NODELAY socket options......


Kind regards,
Coert