[Gluster-users] RAID options for Gluster

[Fernando Frediani (Qube)]

Disks are generally cheap, but there are other things that people normally don't think about like the power to run them, the space they consume in a array, etc. Use RAID 10 in a Gluster environment I think it's a total waste of space as that will give you 1/4 of the Raw space. I'm of the opinion that if you need something to perform better than the concern with amount of total space you would use another solution with RAID 10. (pure XFS or XFS+DRBD, etc)
Given that Gluster is not for high performance (low latency) applications, RAID 5 seems to be a good option given that you still have the ability to replace a disk if it fails and even in a very unlikely event that a you loose a entire array you will have you data replicated somewhere. Hopefully for reads Gluster should be able to read round-robin from both copies to improve throughput.
Unfortunately Gluster doesn't yet have the ability to be aware of bricks on the same node and don't put data there. That would allow create more than one set of RAID on the same server and avoid going over 12-16 disks in a RAID 5 array.

Fernando

-----Original Message-----
From: gluster-users-bounces at gluster.org [mailto:gluster-users-bounces at gluster.org] On Behalf Of Arnold Krille
Sent: 15 June 2012 23:10
To: gluster-users at gluster.org
Subject: Re: [Gluster-users] RAID options for Gluster

Gotta wear my BAARF-hat:

On 15.06.2012 12:14, Fernando Frediani (Qube) wrote:
> Going to the idea of using RAID controllers would you think that for say 16 disks(or 12) Raid 5 would be fine  given the data is already replicated somewhere in another node in a very unlikely event you loose a node.
> Now in a node with more number of disk slots could create multiple Raid 5 logical volumes, but will Gluster be smart enough to not put replicated data on two logical volumes residing on the same node ?

Using raid5 will just leave you with reading from at least two disks then writing to two disks instead of just writing your data to disk.
Unless write-performance is of no interest to you, you should re-think raid5...

If disks are pricey for you, just use all of them and deal with the failed bricks. If disks are cheap, just put always two together in a raid1.

Have fun,

Arnold

(*) http://www.miracleas.com/BAARF/
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