I have a question of anyone who either has done , or has fully proven the
process of, a  backout to V2  via a restore of the DB after upgrading to V3
and running for some period of time. Searching  the list archive  I have
seen some discussion about this topic but no definitive answers to these
specific questions:

Prior to the Upgrade my plan is to migrate all data from our primary disk
storage pool to tape, mark  the tapes 'readonly' so that initially no
storage pool volume  (disk or tape) contains both V3 and V2 data. So If
after the server is upgraded, then data under V3 having been stored in the
disk storage pools, I decide to restore back the V2 DB,  in addition to the
DB restore do I need to:

A)Put the disks in the storage pool back like they were (empty) prior ro the
upgrade? I If so would I need to 'format'   those disks or  use a DFDSS
backup  to restore them back?( my thought was to speed things up by taking a
backup of a single disk storage pool  volumes then restore all the volumes
using that one backup by renaming the data set each time)

B) Restore the ''volume history" file or preserve the old V2 file and fall
back to it?

C) Restore the "recovery log"  file or preserve the old V2 file and fall
back to it?