[Gluster-users] Best practices for creating bricks
B.Candler at pobox.com
Thu Nov 1 17:36:55 UTC 2012
On Wed, Oct 31, 2012 at 03:59:15PM -0400, 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?
I would recommend neither. Remember that drives *will* fail and you need to
be ready to handle these events.
- a RAID0 array has the problem that if one disk fails, you lose the entire
filesystem. Therefore you replace the bad drive, make a fresh filesystem,
and then have to resync the *entire* contents from the other gluster node.
If you get a second disk failure during that time, you have lost everything.
- separate disks per brick is less bad, but is harder to manage. A disk
failure involves swapping the drive, building a new filesystem on it,
re-adding it into gluster, and letting it resync across. This needs to be a
well-trodden path operationally, and also you need suitable monitoring in
place to know when a brick has gone down.
Personally I would say: if write performance is relatively unimportant, then
use RAID6 for the arrays. If write performance is important, then use
RAID10 (and accept a 50% loss of capacity)
What you get from either RAID6 or RAID10 is a no-brainer way to replace
failed disks and have the array reconstruct itself automatically, plus
standard tools for monitoring and managing the array.
This is my personal point of view: others may differ. It also depends on how
important your data is to you (but the implication from building a
replicated volume is that your data *is* important)
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