[Gluster-users] Gluster on a Xen cloud - Questions

Paul Hieromnimon paul.hieromnimon at gmail.com
Mon Mar 2 19:48:46 UTC 2009

I am considering using Gluster to build a Xen hosting cluster/cloud. Xen
requires shared storage in order to do a "live migration" (move a virtual
machine from one host to another without taking it down) so that the vm's
disk image is available on the machine it gets moved to.  The typical
deployment scheme for this is a SAN, but a SAN is expensive both in terms of
the hardware, and rack space - compute node can hold 4TB worth of drives, so
why not use that instead of getting a big SAN box?

I'd like to be able to use Gluster in such a way that:

1. The deployment is "symmetrical" - every machine is both a server and a

2. I can add another machine to the pool and add its storage space to the
pool without having to take down the whole cluster.

3. Use Gluster for redundancy instead of RAID.  It would be nice if I can
lose any single hard drive and/or entire server and still have access to
100% of all the data in the pool.  In this sort of setup, is it possible to
limit the number of copies of data to 2 or 3, or if I have 10 machines, will
I be forced to have 10 copies of the data?

4. Get good performance.  Will i get acceptable performance through gigabit
ethernet, or do I need 10 gigabit ethernet or infiniband to have something
decent?  Because I want a configuration where each machine is both a client
and a server, will performance degrade as I add more machine such that the
network needs to handle n^2 connections, where n is the number of servers?
Or will performance improve because data will be striped across a lot of

5. How is OpenSolaris support?  I'd like to be able to use ZFS as the
underlying filesystem, although I'd be happy with Linux or NetBSD too.

6. I spoke to Hitesh and he said that files have an affinity for the machine
that's accessing them.  Suppose I live migrate a Xen vm to another machine,
will it's disc image eventually physically make its way over to that

I would like to thank in advance anyone who answers these questions for me.
I am new to Gluster and distributed filesystems so I apologize if any of my
questions are stupid.
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