I'm looking at providing replication for a KVM setup, so I'm reading some literature to get a sense of what the best approach is for data replication. I'd prefer to use something free but off the shelf. A solution like Gluster exporting iSCSI luns might work, but it appears their quorum methods are not very applicable for n=2. Failover capable NAS platforms don't appear to be a thing. So far, I'm leaning towards DRBD either on bare metal or on top of MD on the VM hosts themselves. Of course, this is somewhat limited in terms of expansion capability. What have others used in the past and had success with?