Based upon current technological realities, my current belief is that
traditional backup schemes are just no longer tenable for file system
recoveries.  Disks are much too big these days, tapes are sluggish,
and needs too immediate.

What makes more sense now is to protect against file system loss via
mirroring, which allows immediate "recovery" should one of the concurrent
images be lost.  Standard file system backups should also occur, but
rather than a primary recovery vehicle, they would serve as "safety"
backup, plus serve the purpose of recovering from the inadvertent
deletion of individual files.  And the multiple generations of
conventional backups allow for data recovery when some kind of data
corruption had gone unnoticed for a while.

In the past we could do one backup a day and in a file system recovery
could luxuriously tell the file owners that N hours of data could not
be recovered, per standard conventions.  That model just doesn't work
any more.  I remain a supporter of the ADSM philosophy, but the
approach to utilization has to be tempered by contemporary realities.

    Richard Sims, BU