[Linux-cluster] Mirror Volume Pairs

[pheeh at nodeps.org]

I am purchasing the equipment to attempt a configuration I found here:

http://www.redhat.com/magazine/008jun05/features/gfs/#fig-mirroring

How does GNBD able to export the mirrored drives?  How would the mirror be
created?  If gnbd exports a local device, lets call it /dev/md0, how does
the local drive actually get mirrored from the drive of the second
machine?

I haven't been able to locate too much information on this mirror volume
pairs, is there a document anywhere that could explain the setup?

The goal is to get two machines, each with two 500 Gig drives to use gnbd
multipath to export their local drives as a single source...thus there
would be failover just as described in the document.