"A shelf can certainly have problems like any electronic device, I just question whether isolating aggregates to particular shelves solves a real problem."--- That's been my thinking the whole thread.
All great thoughts, but it's really deep in the weeds to waste time over thinking the problem on enterprise HW, using retail JBOD thinking.
We're way down into the .00x afr percentages here even where specific targeted/found bugs actually exist. Add more decimal points for the much more rare smoke events that can kill a shelf.
ONTAP does a good job at layout given a lot of practical experience/data based on best placement for highest reliability. _________________________________Jeff MohlerTech Yahoo, Storage Architect, Principal(831)454-6712 YPAC Gold Member Twitter: @PrincipalYahoo CorpIM: Hipchat & Iris