[Gluster-users] Question about Volume Type when bricks are on SAN

[Mike Hanby]

Howdy,

I'm in the process of setting up GlusterFS for our users to test. I'd like some opinions about which volume type makes sense for our configuration.

Here's our hardware config:
2 x Gluster servers with 4Gbit FC and 10Gbit Ethernet (both FC and 10GigE are dual path to their respective switches)

Each Gluster server has been allocated a single 9TB LUN (if it makes any sense to do so, I could have the SAN admin provide many smaller LUNs per server and use LVM to combine into single brick)

The servers are attached to the SAN via 4Gbit fiber channel. The SAN uses RAID 5'like to create the LUNs (or more likely the volume from which the LUNs are carved).

So, here's my dilemma. Part of me says, 18TB of raw storage is a whole lot better than 9TB, and given that the LUNs are on enterprise hardware, why not create a Distributed volume? It should be safe pretty safe, right?

But then I think, well if server2 goes down, then all of the files on its LUN are not accessible to the clients, so maybe Distributed Replicated makes more sense, at the cost of only providing 9TB raw to the end users.

Would a Distributed Stripe (or Distributed Replicate for that matter) make any sense in this configuration, given that both bricks are physically on the same SAN?

One final question, is there were a way in Gluster to have a Distributed with failover, where if server2 dies, server1 can mount server2's LUN, once server2 was back online, server1 could be told to stop hosting the brick and return it to server2.

We do this with Lustre and it's worked well so far.

Thanks for any insight,

Mike