Thanks for that symm.

I agree that having 2 SAS Raid controllers accessing the same disks is a scarey thought, but we would be using 2 SAS HBAs accessing the same (external SAS) LUN, which sounds like something EVMS (after a quick read up on it) could do, if it was still current.

So the final verdict is that...
- for iSCSI automatic failover, we must duplicate all storage yes?
- for NAS services though, with the use of async volume replication, we could use fewer bigger & slower SATA disks, if faster smaller SAS drives were on the "primary" side, yes?

Thanks