Hi,
I have a small cluster that I use to host a collection of Xen virtual
machines. I just expanded from 2 nodes to 4 nodes and am looking for
some advice re. configuring a storage subsystem.
The current (2-node) configuration is simple:
- 4 disks per node
- md-based raid
- lvm
- DRBD to replicate (some) volumes between the two nodes
- (some) VMs set up for auto-failover on node failure (pacemaker, etc.)
In moving to 4 nodes, I'd like to add some flexibility to move VMs
across all 4 nodes, but... that requires using something other than DRBD
to replicate volumes. I'm thinking of something with the following
characteristics:
- 4-node storage cluster (4 drives per node, total of 16 drives in the
storage pool)
- 4-node VM cluster
- using the SAME 4 nodes for both
- note: I've got 4 gigE ports to play with on each box (plan on using 2
for outside access, 2 for storage/heartbeat networking)
GlusterFS stands out as the package that seems most capable of
supporting this (if we were using KVM, I'd probably look at Sheepdog as
well).
So... a few questions:
- it looks like running replicated volumes, across 4 nodes, will provide
for redundancy and support migration/failover (am I right in this? or
should I be looking at running RAID on the individual nodes as well?)
- what kind of performance hit is involved in replicated volumes?
- is there anything more efficient in disk use (i.e., mirroring 4 copies
eats up lots of disk, is there anything equivalent to RAID 5/6 that is a
little more efficient while maintaining redundancy?)
- am I missing anything (either re. GlusterFS or other alternatives)
Thanks very much for any suggestions and advice.
Miles Fidelman
--
In theory, there is no difference between theory and practice.
In<fnord> practice, there is. .... Yogi Berra
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