RE: Why not IPL? (Was: RE: Long backup time after IPL)

Check the size of journal receivers before the shorter and longer save
times.  If the receivers are bigger then it is taking longer to copy them to
tape.

Make sure that the journal receiver you are saving is detached before you
start to save it.

Check to see if you use more tape on the longer days than on the shorter
days (DSPTAP).  If the tape usage is the same then the system is doing more
associated work.  If the tape usage is higher, then it is taking longer
because there is more data.

The save time for a source file is very long compared to the save time for a
single member file of the same size.  Each member takes time similar to
saving a file.  If the long save includes a source file and the short saves
don't include that file, well then, there you are.

If you recently added disk drives and you didn't run Disk Balance to
conclusion, I have another idea.  As the system runs, all new objects will
be allocated to the new drives - that's where most of the empty space is.
After an IPL, the job temporary spaces are all gone so those drives are
relatively empty.  If you are saving to a save file, it will be allocated to
the relatively empty space.  If that empty space is on just a few disk
drives, the save operations may overload the disk IOP or (possibly) the disk
arms during the operation.  I think you would need a very fast machine to
overload the arms.

If there are several concurrent save operations executing to save files on a
relatively few disk arms and if those disk arms are all in one RAID set and
the system is fast, overload is likely.

If it isn't any of these and if this is important to you, please contact me
offline.  I can find it.  If it isn't important to you, why worry?  I assume
that you have tested your backups to insure that you can restore your
systems from any of them ... is it possible that the short ones don't have
the same data as the longer ones?

Richard Jackson
mailto:richardjackson@richardjackson.net
www.richardjacksonltd.com
Voice: 1 (303) 808-8058
Fax:   1 (303) 663-4325

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of
oliver.wenzel@cibavision.Novartis.com
Sent: Tuesday, July 18, 2000 5:04 AM
To: MIDRANGE-L@midrange.com
Subject: AW: Why not IPL? (Was: RE: Long backup time after IPL)


        Hello,

        > 1) are you running 24/7?
        > 2) are you doing save while active?
        > 3) are you just saving changed objects?
        > 4) are you journaling?

        No, no, no and yes (partially). Our system is closed to users each
night to do day-end
        processing and backups.
        The backup job in question runs mon-fri and the joblogs from each
session are identical.
        Most of our data is backed up in two other jobs (about 40GB). So
there's mostly static
        stuff in this backup.

        Regards,

        Oliver


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