SAN replication

[ShadowMan]

I'm not using the latest version of the Lefthand software so maybe this has changed but you'll be better off going for 3 units, having 2 in the same location. The SAN needs quorum so if the link goes down between the sites (split brain scenario) then the 2 units will still be working, the last unit will stop exporting volumes.

You can accomplish this with 2 units by starting a virtual manager but that is a manual action and your san will be down until done.

Best option if you only want 2 physical SAN's is a Failover Manager (FOM). Runs as a virtual appliance in VMplayer on any physical server and acts as the 3rd node for quorum. Place this on a box and off you go. It is also free and included on the management DVD which comes with the LeftHands or from the HP website.

For a cheaper SAN solution look at HP VSA (Virtual SAN Appliance) if you have or are going to have a VMware environment. Runs as a virtual machine under the VMware hypervisor and turns physical storage on a pizza box server into a fully presented LeftHand.

I managed to spec up a dual node HP VMware cluster solution with 2 HP VSA's (1.5TB per node) and a management box to run the VMware Vcentre server and FOM for around £23k. This presented 16 Cores and 96GB of RAM to the VMware environment.

This was inclusive of all licensing for VMware and the VSA with 24/7 (3 years) support on all components including the LeftHand software. VSA license is about £2.5k so makes a cheap SAN option.

We decided not to go for it at work as our Technical Architect does not like the stability of HP LeftHands (His opinion not mine).

The HP VSA's are basically the software from a P4000 LeftHand running in a virtual environment and worked great in my test lab.

 

[Vanilla]

If your environment has a third site, even it it's just a remote office that has connectivity to both DCs then that's the best place for the 3rd node witness.