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backing up Statice databases

    Date: Thu, 9 May 91 16:26:35 EDT
    From: rshapiro@arris.com (Richard Shapiro)

    According to the documentation, there are only two ways to back up
    Statice dbs: (1) perform a real backup using one of several obsolete
    (and very limited capacity) tape formats or (2) dump the dbs as ascii
    files. Neither of these seem like very attractive options. Are there,
    by any chance, other unpublicised forms of backup? In particular, it
    would be useful if the regular Statice backup facility could be made
    to work on some modern, fast, high capacity medium (DAT, for
    instance); or if it could quickly generate relatively small binary
    files on a Unix system, which could then be backed up in the usual
    Unix fashion. Ascii dumps take far too long to generate and reload,
    and produce huge files; and it seems silly at best to be using ancient
    (and slow) 40 MB cart tape formats.  It seems especially silly to have
    to go out and buy a drive of this sort in 1991.

When we upgraded from a 3650 to an XL last summer, we started using the
Exabyte 2.3 gb tape drive; it uses a SCSI interface.  Statice dumps came
down from 30 minutes to 3 minutes.  LMFS dumps, from the better part of
a day to 35 minutes, and from 3 tapes to << 1.  We don't even do
incremental back-ups any more.  The Exabyte is a helical-scan device,
and uses the small Video-8 tapes, which can be bought for around $8 at
most stores that sell video tapes, which makes them about 300 times more
cost-effective than the 40mb cart tapes.

We certify our own tapes by writing/reading 4 different patterns.  Even
with their incredible speed, and using buffering and some low-level
Ivory block-register optimizations, it takes 21 hours to certify one
tape.  In the process of pushing the tape so hard, we uncovered an Ivory
IO bug that would cause a byte or two at a time to cross over to another
stream; this would usually appear as isolated garbage in, say, a file
transfer.  We have a temporary patch that has been working fine; the
real one will be in 8.1.

You might ask Symbolics if these drives could be attached to a MacIvory,
and whether the performance would be as good.

    Any suggestions? Please reply by email to rshapiro@arris.com. 

    Thanks --