We've done that, but when a single project out grows a volume, then we start needing to shuffle data... it's a pain.
If I could have more volumes, then I'd use them over qtrees, but then when an Aggr fills, I need to move volumes. It's a pain.
That's why I like the idea of the Acopia product. I wish NetApp would realize that and come out with their own storage virtualization product to put in front of backend NetApps. Would be really nice.
Course I'm a mostly NFS only shop.
Aren't you basically describing ONTAP GX (on the fly volume moves, 1000 volumes per pair of filers, up to 24 filers using a single namespace which can be used to stitch volumes together etc)?