ADSM-L

EXPORT NODE - VM server

1994-03-01 14:29:18
Subject: EXPORT NODE - VM server
From: "Wayne T. Smith" <WTS AT CAPSLAN.CAPS.MAINE DOT EDU>
Date: Tue, 1 Mar 1994 14:29:18 EST
In an effort to get "point-in-time-restore" capability for a few of our crutial
systems, I've been looking at EXPORT NODE.  The process is not a
pretty sight. :-(

        EXPORT NODE is good because it doesn't cost me DB
        space.  It is bad because I have to manage the process
        including what's where.  But the reason for this mail are
        a few other problems ...

A minor problem: the EXPORT NODE messages are not returned to the
command sender, at least when entered via the SMSG interface (they are
in the ACTLOG and are nicely labeled EXPORT NODE).

A less minor problem: the number of bytes to be copied was reported as
a negative number for my 2-3 gigabyte node.  (There is an open (last I
looked) problem on this).  The actual amount of data copied is also a
negative number;  I'm not sure if this is the same message or another
problem.

A strange-ness, but not necessarily a problem:  if you don't give ADSM
enough volsers on which to place the data, ADSM issues a mount for
volume "export.n", where "n" is one more than the number of volsers you
gave it.  Not a problem, but not documented (anyplace I could find).

A larger problem was the cpu and wall-clock time used.  An EXPORT
NODE with PREVIEW=YES crunched for a couple of hours on a smallish
50,000 file node.  I canceled a similar request on a 250,000+ file node a
day or so later.  In all cases, a QUERY PROCESS output seems to imply
ADSM is sorting.  Actually writing to tape was no better.  On a recent trial,
ADSM took the following times filling 3490 cartridges: 80 minutes, 25
minutes, 190 minutes, and 60 minutes (with no interference from other
applications).  Given that our mainframe backup software (SYBACK) can
spinoff a tape in 10 minutes or less ... this is horrible.  Considering what
the PREVIEW=YES took, it's not unexpected.

These things just make EXPORT NODE less useful.  Where I have my
ADSM server physically close to client nodes, it makes "offsite backup"
expensive indeed.

Thanks for listening,

cheers,

Wayne T. Smith
Systems Group -- CAPS        internet: wts AT maine.maine DOT edu
University of Maine System   BITNET/CREN: WTS@MAINE
<Prev in Thread] Current Thread [Next in Thread>
  • EXPORT NODE - VM server, Wayne T. Smith <=