[Gluster-users] GlusterFS on a two-node setup

[Brian Candler]

On Sun, May 20, 2012 at 01:26:51AM +0200, Ramon Diaz-Uriarte wrote:
> Questions:
> ==========
> 
> 1. Is using GlusterFS an overkill? (I guess the alternative would be to use
>   NFS from one of the nodes to the other)

In my opinion, the other main option you should be looking at is DRBD
(www.drbd.org).  This works at the block level, unlike glusterfs which works
at the file level.  Using this you can mirror your disk remotely.

If you are doing virtualisation then look at Ganeti: this is an environment
which combines LVM plus DRBD and allows you to run VMs on either node and
live-migrate them from one to the other.
http://docs.ganeti.org/ganeti/current/html/

If a node fails, you just restart the VMs on the other node and away you go.

> 2. I plan on using a dedicated partition from each node as a brick. Should
>   I use replicated or distributed volumes?

A distributed volume will only increase the size of storage available (e.g. 
combining two 600GB drives into one 1.2GB volume - as long as no single file
is too large).  If this is all you need, you'd probably be better off buying
bigger disks in the first place.

A replicated volume allows you to have a copy of every file on both nodes
simultaneously, kept in sync in real time, and gives you resilience against
one of the nodes failing.

Regards,

Brian.