[Gluster-users] Bricks suggestions

[Brian Candler]

On Wed, Apr 18, 2012 at 09:54:58PM +0200, Gandalf Corvotempesta wrote:
>    we are planning a new infrastructure based on gluster to be used by
>    some mail servers and some web servers.
> 
>    We plan 4 server, with 6x 2TB SATA disks in RAID-5 hardware each.
> 
>    In a replicate-distribute volume we will have 20TB of available space.
> 
>    What do you suggest, a single XFS volume and then split webstorage and
>    mailstorage by directory or do you suggest to create two different
>    mount points with different replicate-distribute volume?
> 
>    any performance degradation making 2 or more volumes instead a single
>    one?

Much less than the performance degradation you'll get from using RAID-5!

If you use 6 x 3TB disks in RAID10 you'll have almost the same amount of
storage space, but far better performance, at almost the same price.  I'd
say this is very important for a mail server where you are constantly
writing and deleting small files.

RAID10 with a large stripe size should localise file I/O from one user to
one disk (read) or two disks (write), so that there is spare seek capacity
on the other 4 disks for concurrent accesses from other users.

As for partitioning: note that you can create separate bricks on the same
disk.  e.g. if the RAID arrays are mounted on server1:/data, server2:/data
etc then you can create your web volume out of

  server1:/data/web server2:/data/web ...etc

and your mail volume out of

  server1:/data/mail server2:/data/mail ...etc

This doesn't gain you any performance, but gives you a little more
flexibility and manageability (e.g. you can more easily look at I/O usage
patterns separately for the two volumes, or migrate your web volume onto
other bricks without moving your mail volume)

Regards,

Brian.