ADSM-L

No query restore rep=all -ifn

1998-11-12 18:01:33
Subject: No query restore rep=all -ifn
From: Julie Phinney <jphinney AT HUMANA DOT COM>
Date: Thu, 12 Nov 1998 17:01:33 -0600
I just got very bad news today from IBM about ADSM and I'm hoping that it's
wrong and one of you can shed some light on this situation.
Our "theoretical" disaster recovery plan is to use ArcServe weekly and ADSM
nightly and when a disaster happens, restore from the weekly backup with
Arcserve... then do an ADSM restore  -REP=ALL  -IFN     to JUST restore
anything  that's newer than the weekly backup done by Arcserve.   We'd
expect a reasonable few hours to scan a 10 GB drive and restore anything
that's newer.
Well we had a  Novell machine die a couple weeks ago.  Around 10GB,  and
450,000 files.  The mainframe ADSM 3.1.2.0 server is using OS/390 2.5,
TCPIP 3.4 and a Fast Ethernet 100mbs  OSA2 adaptor.
We restored using a weekly Arcserve backup.  There should have been few
changes left to restore using ADSM.    The ADSM Client was 3.1.0.3.
We started the restore with ADSM  using -REP=ALL  and -IFN   which is a No
Query Restore - our supposed ace-in-the-hole for fast restore.   We let it
run for about 20 hours a day, every day, when we had to stop it for some
reason or another.  It started back in the beginning every day, because
RESTART RESTORE  doesn't work with the -IFN parameter  (IBM created an APAR
on that for me).    After 5 days of starting it back from the beginning
and letting it run for 20 hours and it never finished and not letting the
users have the machine  back   we finally  GAVE UP.   and gave the machine
back to the users.
I noticed the session counts on that 20hour thing  every day   showed  6 or
more GB  being sent.  And I KNEW  very little should actually be moving,
and it SHOULD be less and less every day.   And it was mounting many tapes
every day.   It was as if we weren't using -IFNewer.

So I did a trace for IBM.   I picked a small directory that has 30 files in
it and no subdirectories.  It needs nothing restored.  I did a RES
-REP=ALL  -IFN.    It mounted 9 tapes and showed session counts with more
bytes than the total of what was in the directory.  And NOTHING was
bytes than the total of what was in the directory.  And NOTHING was
restored (as nothing should have been).
And IBM told me that is how a No Query Restore works with -IFN.     EVERY
tape is mounted, EVERY FILE MOVED to the client    OVER THE NETWORK   where
it is then compared.   And only replaced if the file is newer.
They will submit a design change request for me.

So then, is our only choice for Disaster Recovery  to use nightly Arcserve?
Or nightly ADSM, which has already been ruled out as un-viable for quick
simultaneous recovery of many large drives.   Can't we make these things
work together?   How can I get ADSM to do a reasonably quick scan of the
drive and only move what's newer.  I am astonished that that is how it
works.   I've been using ADSM for years and can't believe I never noticed
before that -IFN moves every file first before it compares it.   Goodness,
it's got to be faster to skip the -IFN and just use  -REP=ALL.
Somebody please tell me  that my IBM rep is wrong before I have to break
this news to management.  Or help me come up with a different combination
of parms to offer as an alternative.
THANKS!!!
Julie
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