[linux-lvm] Mirroring a Drive for load-balancing AND failover

[AJ Lewis]

On Wed, Jul 27, 2005 at 09:06:01AM -0400, Matthew Gillen wrote:
> Fury wrote:
> > I've racked my brain on this one, so hopefully someone will be of some help.
> > 
> > I'm trying to set up two servers which share a drive and do not have a
> > Single Point of Failure.  They are on a local network with each other.
> >  The best solution would be to have /dev/sda1 on one server mirrored
> > with /dev/sda1 on the second server.
> > ...
> > A second solution was to use GFS/GNBD.  I can export each drive to the
> > other server, and do RAID 1 (on both servers) between the local
> > /dev/sda1 and the remote gnbd device.  I then format the raid device
> > with GFS so both servers can mount it.
> > 
> > Surprisingly, this last system works.  Both systems can mount the
> > drive and read-write to it.  However, if either server in this
> > configuration drops dead, the other server cannot deal with the dead
> > gnbd device, and the raid device and mount point are no longer usable.
> >  I'm sure there are numerous other problems with this setup, also.
> > 
> > So I'm looking for ideas.  With two servers, how can I mirror a drive
> > in real-time, and allow for failover?
> 
> You might want to use something more like iSCSI + RAID:
> http://linux-iscsi.sourceforge.net/

How is that different than GNBD + RAID?  The issue isn't the network
transport, it's recovery of a RAID on two nodes simultaneously.

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