[DRBD-user] primary / primary as shared storage

Robert Verspuy robert at exa-omicron.nl
Mon Jul 23 20:26:38 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I just red http://sources.redhat.com/cluster/doc/nfscookbook.pdf

And the purpose of the quorum disk is to have a device, which can be used, 
to determine which of the two nodes will continue, after they loose all 
other contact. So If you don't have a SAN or 3rd machine, you probably use 
an ethernet connection to sync the data????.
DRBD would transfer over the same ethernet connection.
If you loose the sync, (which could be caused by the ethernet connection, 
which is not working anymore). Then DRBD can't get any data synced also.
So the whole purpose of a quorum disk can not be used in this situation.

(Correct me if I'm wrong.. I'm also currently looking for a way to setup a 
loadbalanced NFS server with DRBD, and probably GFS2, but still searching, 
and reading, to find the way I really want to...)


On Mon, 23 Jul 2007, Chris Harms wrote:

> Hi all,
> DRBD appears to be my last resort for salvaging a 2-node Red Hat Cluster
> installation.  I need to setup a quorum disk to which both nodes need to have
> read / write access.  Having not a SAN or a 3rd machine to devote to the
> process presently, I am hopeful that DRBD can function in this fashion.  Both
> nodes will need to make the partition primary and write to it.  The cluster
> accesses the device directly, i.e. I point it to /dev/drbd2.  Preliminary
> results show it could work, but minimalistic startup procedures seem to put it
> into a split-brain state. 
> [From the qdisk manpage]
>    This quorum daemon requires a shared block device with concurrent
> read/write access from all nodes in the
>    cluster.  The shared block device can be a multi-port SCSI RAID array, a
> Fiber-Channel RAID SAN, a RAIDed
>    iSCSI target, or even GNBD.  The quorum daemon uses O_DIRECT to write to
> the device.
> Will some more advanced init scripts make this workable and stable, or is this
> a fool's errand?
> Thanks,
> Chris
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