On 23/02/2011 13:56, David Brown wrote: [...]
Incidentally, what's your opinion on a RAID1+5 or RAID1+6 setup, where you have a RAID5 or RAID6 build from RAID1 pairs? You get all the rebuild benefits of RAID1 or RAID10, such as simple and fast direct copies for rebuilds, and little performance degradation. But you also get multiple failure redundancy from the RAID5 or RAID6. It could be that it is excessive - that the extra redundancy is not worth the performance cost (you still have poor small write performance).
I'd also be interested to hear what Stan and other experienced large-array people think of RAID60. For example, elsewhere in this thread Stan suggested using a 40-drive RAID-10 (i.e. a 20-way RAID-0 stripe over RAID-1 pairs), and I wondered how a 40-drive RAID-60 (i.e. a 10-way RAID-0 stripe over 4-way RAID-6 arrays) would perform, both in normal and degraded situations, and whether it might be preferable since it would avoid the single-disk-failure issue that the RAID-1 mirrors potentially expose. My guess is that it ought to have similar random read performance and about half the random write performance, which might be a trade-off worth making.
Cheers, John. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
