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) Regards, Brian.
