[Gluster-users] Best practices for creating bricks

[Jeff Darcy]

On 10/31/2012 03:59 PM, Kushnir, Michael (NIH/NLM/LHC) [C] wrote:
> I am working with several Dell PE720xd. I have 24 disks per server at my
> disposal with a high end raid card with 1GB RAM and BBC. I will be building a
> distributed-replicated volume. Is it better for me to set up one or two large
> RAID0 arrays and use those as bricks, or should I make each hard drive a brick?
> 
> This will be back end storage for an image search engine with lots of small
> file reads from multiple application servers.

As a very general rule, the "one big RAID" type of configuration will work a
little better, especially for workloads where accesses to blocks within the
same RAID stripe will come close together - large requests, sequential
requests, requests with some other locality of reference.  For workloads
lacking that characteristic, the "many small bricks" approach - essentially
letting GlusterFS manage scheduling instead of the RAID controller - might work
better.  However, there are so many exceptions both ways that no rule of thumb
really suffices.  I highly recommend running your workload or a close
simulation of it on both configurations, to see which really performs better
for your I/O patterns on your hardware.  It's worth the effort.