The RAID in the Mirror

If you have lots of data to store and are figuring out how to lay out your disks, check out Roch Bourbonnais’ WHEN TO (AND NOT TO) USE RAID-Z. (Hey Roch; could you find a slightly less brutal way to format your blog?) For RAID & filesystem wonks only. It’s a lucid, quantitative explanation of the trade-offs between mirroring, striping, and RAID-ing. Some of the narrative is ZFS-specific, but I suspect that the lessons are pretty general. Out there in the real world of production applications, you’d be surprised how often it is, when you’re waiting for a slow app, you’re waiting for the disk, not the CPU. This stuff matters.