I've recently had a number of projects at work that want to mix multiple volume managers on a single server, specifically ZFS and VxVM for SAN volumes (actually, three including SVM for internal boot disk mirroring). The projects generally are for database servers, and want to use VxVM for database volumes because ZFS currently has some serious limitation on database size (limited number of devices recommended in a single zpool) and performance (single threaded checksumming, for one). However, at the same time, they want to have access to some of ZFS's features (in particular, the ability to oversubscribe filesystems, dynamic resize, snapshots and rollback) for some of the other filesystems.

While taking part in a storage install the last few days, including creating and deleting quite a few RAID groups and so forth, I've had to click on quite a few "Are you SURE?!" dialog boxes, even for completely idle, never-used LUNs. Here's an idea for storage management folks: keep a bitmap of recently-accessed LUNs. Specifically, keep two; every five minutes zero the old one and flip them, then set a bit in the active bitmap for each LUN when it's accessed. Then pop up an extra "You've accessed this LUN in the last five minutes! Are you SUPER-SURE?!" scary box if someone tries to delete or in some other way imperil one of those.