On Mon, 3 Jun 2002, Roy Sigurd Karlsbakk wrote: > It'll waste 9 drives, giving me a total capacity of 7n instead of 14n. > And, by definition, RAID-6 _can_ withstand _any_ two-drive failure. This is certainly not true. Combining N RAID-5 into a stripe wastes on N disks. If you combine two it wastes 2 disks, etc. That is, for each RAID-5 you waste a single disk worth of storage for partiy. I don't know what equation you're using where you get 9 drives from. As far as it's ability to withstand _any_ 2-disk failure... I'm not sure what you mean by definition. RAID-6 implemations don't follow a standard because there isn't one. Depending on how it's implemented, RAID-6 is not necessarily able to withstand a filaure of any two disks. We can argue as much as you want, but I'm not willing to invest the time. > With a 1500MHz Athlon on a typical file server where there's not much > writes, the CPU is sitting there chrunching RC5-64 som 99,95 % of the > time. I don't think it'll make much differnce with today's CPUs It's up to you to decide if the performance trade-off is worthwhile. I merely trying to point out that system with 2 RAID-5 is likely to incur the same CPU hit as a single RAID-6, implemented in the kernel. --- Derek Vadala, derek@cynicism.com, http://www.cynicism.com/~derek - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
