As feared, it turns out that we cannot do an afs volume dump to the afs volume partition of the fileserver without grinding hcoop to a halt. ClintonEbadi's early test resulted in fritz thrashing itself into oblivion, and the entire site losing access to the fileserver (never fear! services recovered flawlessly on their own mere minutes after killing the dump). Neither deleuze nor mire nor hopper have the free space required for backing up all of the data we have in afs now, never mind future data. The new server is at least a month and a half away, and we really need backups to have not stopped working six months ago.
Thus: we need a pair of drives for a third RAID1 on fritz, dedicated to backups. We have nearly 200G in data that needs backing up now, so 500G is the absolute minimum. However, much larger drives are not much more expensive and it's not unrealistic that we would have well over 500G of data in need of backing up 18 months from now (inserting new stuff at the data center is a pain).
1. Drive Options
We have a single hot swap caddy on hand because of the failed drive. We need a single 3.5" caddy for the PowerEdge 2970.