Whatever you do, there is always a tradeoff between reliability, performance and efficiency. I think all concerns are well answered in NetApps storage resiliency paper: Do Raid-DP, do backups, do HA, do multi-pathing, do disk auto assign, have spare parts (etc) and you'll have 99,999% availability and a max of performance, as long as you can afford it.
And btw., limiting you and your system to have 1 aggregate/shelf produces a lot of work reassigning disks/spares over time when your systems grows. After 10+ years of operating netapp systems, I always had my aggregates (volumes earlier) spread across all shelves and never had any trouble with it.
-SF
Am 07.04.2011 21:58, schrieb Ray Van Dolson:
Best practice (based on my reading of the archives) seems to be to distribute disk membership in an aggregate across disk shelves.
This would appear to be for performance reasons primarily (less chance of saturating a shelf's "uplink" to the controller), but how does it affect reliability?
If I limit myself to one aggregate per shelf, if I lose that shelf I lose only the one aggregate. If aggregates are distributed I could lose all of them.
My thought is that the chance of the shelf failing is actually pretty slim as its hardware isn't all that sophisticated.
And obviously there are performance penalties for limiting to one aggregate per shelf (disk count maximums).