ADSM-L

How does changingretries work?

2015-10-04 18:03:48
Subject: How does changingretries work?
From: INTERNET.OWNERAD at SNADGATE
To: Jerry Lawson at ASUPO
Date: 11/13/97 12:14AM
Be careful with the distinction between an open file and shared dynamic
backups.  While they sort of imply the same thing, sometimes they don't.

Dynamic backups mean that if the data changes while doing the backup, it will
be backed up anyhow.  Changed means that ADSM detected that the file was
different.  As I understand it, this is done by comparing date/time stamps,
as well as file size information.

If you say Shared Dynamic (or Shared Static), this means that if ADSM detects
a change, it will retry the backup.  The default is 4 times.

The detection of the file changing is made while it is being backed up.  If
it is determined that a change occurred, the retry is done immediately.

Open file handling will vary somewhat between operating systems, but I
believe the basic concepts are the same.  If a file is "open" it is not
necessarily changing.  Therefore, a backup can be made of an open file
without having ADSM detect a change, and thus will not be retried.

Most operating systems support some way of opening a file in an "exclusive"
manner - that is when the file is open, no other user/application can access
the file.  When this occurs, ADSM, like any other application, cannot access
the file, and cannot back it up.  This has nothing to do with whether you
have static or dynamic mode set - the operating system will not permit the
access.

I hope this helps clarify the situation.

Jerry Lawson
jlawson AT thehartford DOT com

______________________________ Forward Header __________________________________
Subject: How does changingretries work?
Author:  INTERNET.OWNERAD at SNADGATE
Date:    11/13/97 12:14 AM


Hi,

I am a little unclear as to how the changingretries option works.

We are performing an incremental backup to a copy group that uses shared
dynamic serialisation. A large proportion of the files being backed up are
open. We have changingretries set to 4.

When ADSM encounters one of these open files, it should retry (and I guess
is because all of the files get backed up). My question is how long does
ADSM wait before retrying? Is it immediate? A fixed interval? Random?
Something else?

We are trying to reduce the backup times for some machines and are trying
to work out if reducing changingretries will be beneficial.


thanks,

Trevor
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