On Tue, 2002-03-26 at 13:19, Frank Samuelson wrote: > 900TB with 100G disks striped 3 disk mirrors: 27 disks > 900TB with 100G disks RAID5 x RAID5: 16 disks > 900TB with 100G disks RAID6: 11 disks > > RAID5 x RAID5 would survive any three disk losses. > > Mirroring is always much more expensive. It's cheaper to do things > intelligently. Mirroring is always much more expensive in terms of disk space. It's always much cheaper computationally. The converse is true of doing one of the more complex RAID levels. Processing power is in abundance on x86 machines, while memory bandwidth, and I/O bandwidth are incredibly hard (I'd say impossible, but somebody would flame me) to come by. On other machines, such as the S/390, processing power may not be as readily available, but the I/O bandwidth is measured in completely different orders of magnitude. So, there's probably a place for all of the above RAID levels, although the latency in RAID 5 and RAID 6 will keep me away from them. Greg -- Portland, Oregon, USA. - 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
