backing up several machines to one tape?

[Neal Feinberg <nealf@harlequin.com>]

   Date: Fri, 30 Apr 1993 08:38-0400
   From: Craig Lanning <CLanning@pdesds1.atg.trc.scra.org>

       Date: Fri, 30 Apr 1993 01:50 EDT
       From: kmp@harlequin.com

	   Date: Thu, 29 Apr 1993 20:46 EDT
	   From: K. Mark Alexander <kma@samson.cadr.amis.com>

	   ... The real question is: How do you retrieve from a specific hosts' lmfs
	   backup dump?

       Speaking of "how do you retrieve", I recently contemplated buying an
       exabyte drive for my Macivory and was independently warned by several
       people that (in their opinion) exabyte is a terrible medium in which to
       do backups.  The word I got is that people have found it to have
       higher-than-average risk of not being able to retrieve data from at all,
       and that it's especially bad in the case where you're reusing the same
       tape over and over (as one would presumably do with incrementals).  I
       didn't try it myself, so this is third-hand info at best, but it's worth
       actually checking some of your exabyte backups before you are desperate
       for them to convince yourself that they're really storing your data in a
       retrievable way.  Personally, I wish smbx would provide support for DAT
       drives, which are more popular, more widely available, much cheaper, and
       reputed to be more reliable.

   The Exabyte tapes seem to be fairly reliable.  I backup my XL1200 onto
   one every week and we backup several Gigabytes worth of Sun and DEC
   filesystems onto them each day.  The real important thing to remember is
   that Exabyte drives show the effects of dirty heads sooner than other
   drives so it is very important to clean the drive regularly.
   Fortunately, Exabyte produces their own head cleaner which makes the job
   very easy (you put the cleaning tape into the drive and it does the
   rest).

   Craig Lanning <CLanning@trc.scra.org>
   Grumman Data Systems
   North Charleston, SC

If you decide to use exabyte technology, be sure to use data-grade 8mm
tape.  The K-mart special 8mm video-grade tapes might appear to work
until you really need the data off the tape.  Be sure to use the
compare backup tape facility for checking your backups from time to
time.  As Craig says, clean heads are also vital.