+-- "Bruce Sterling Woodcock" sirbruce@ix.netcom.com once said: | Depends on the amount of disk you are talking. Note that I didn't | say you could buy a second duplicate filer, just that you could get a | second one. Do the math and you'll come out on top.
I agree, certainly if you're talking about 2TB or something like that, the cost of the additional disk gets very high. | | That's because the "some cheaper DAS with X diskspace" would | not have compareable performance and RAID protection. If you | cost out your DAS of comparable performance to a filer, but with | twice the disk (for RAID 0+1), it will be more expensive.
I'll argue that you get just fine "RAID protection" from 0+1 on any reasonable array. Performance is another matter, but I didn't think we were trying to compare apples-to-apples there. Performance and features are why you'd spend the extra money on a Netapp in the first place.
Oz