Big JBOD: What would you do?
By relling on Jul 17, 2006
I'm preparing some analyses on RAS for large JBOD systems such as the Sun Fire X4500 (aka Thumper). Since there are zillions of possible permutations, I need to limit the analyses to some common or desirable scenarios. Naturally, I'd like your opinions. I've already got a few scenarios in analysis, and I don't want to spoil the brain storming, so feel free to think outside of the box.
If you had 46 disks to deploy, what combinations would you use? Why?
- 46-way RAID-0 (I'll do this just to show why you shouldn't do this)
- 22x2-way RAID-1+0 + 2 hot spares
- 15x3-way RAID-Z2+0 + 1 hot spare
Because some people get all wrapped up with the controllers, assume 5 8-disk SATA controllers plus 1 6-disk controller. Note: the reliability of the controllers is much greater than the reliability of the disks, so the data availability and MTTDL (mean time to data loss) analysis will be dominated by the disks themselves. In part, this is due to using SATA/SAS (point-to-point disk connections) rather than a parallel bus or FC-AL where we would also have to worry about bus or loop common cause failures.
I will be concentrating on data availability and MTTDL as two views of RAS. The intention is that the interesting combinations will also be analyzed for performance and we can complete a full performability analysis on them.