On Wed, May 31, 2006 at 04:27:54PM +0200, Mattias Wadenstein wrote: > On Wed, 31 May 2006, Bill Davidsen wrote: > >Where I was working most recently some systems were using RAID5E (RAID5 > >with both the parity and hot spare distributed). This seems to be highly > >desirable for small arrays, where spreading head motion over one more > >drive will improve performance, and in all cases where a rebuild to the > >hot spare will avoid a bottleneck on a single drive. > > > >Is there any plan to add this capability? > > What advantage does that have over raid6? You use exactly as many drives > (n+2), with the disadvantage of having to do a rebuild without parity when > a drive fails and a raid failure at a double disk failure. Advantage: - Easier to calculate the checksum (RAID5 XOR instead of a generator polynome with RAID6) - Higher throughput compared to standard RAID5 - Actually uses the hot spare Disadvantage: - Doesn't protect against double disk failures, but RAID5 also doesn't Note that you could also do RAID6E. Erik -- +-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 -- | Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands - 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
