Re: Copy Serialization Dynamic Impact

If the large files are SEQUENTIALLY written files, a fuzzy backup is usually
OK.
An example of this is the dsmsched.log file - it's always being written to
during a backup.
Same thing on some AIX clients that have sequentially written logs.
We set up a special management class with SHARED DYNAMIC and use that for
these files.
Usually what you get is a backup of the file UP TO THE POINT that was being
written at the time TSM tried to backup, and that is fine (and certainly
better than nothing).

However, if the files are DATA BASES of some kind where the changes could be
made in the middle of the file, DON"T use SHARED DYNAMIC.  You will get a
backup that looks oK, but when you restore it, you could have damage in the
middle somewhere that will not be apparent until you try to access that
record.

For files like this, you have to figure out what program is using the file,
and schedule your backups sometime when you can shut it down.  Or use a TDP,
if it's a data base.  Or export the data to a flat file and back up the flat
file.
There are many techniques, depending on your circumstances.  .



-----Original Message-----
From: Scott Walters [mailto:scott_walters AT MACKTRUCKS DOT COM]
Sent: Thursday, October 03, 2002 2:17 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Copy Serialization Dynamic Impact


Hey all,

        In setting up our TSM server, we've noticed that many clients have
large
sessions because they have been re-transmitting files that are changing.
  We had the Copy Serialization set to Shared Dynamic CHANGINGRETRIES=4.
  We then bumped CHANGINGRETRIES down to 1.

        At this point we still have a few boxes that are backing up large
files
that are being retransmitted.  We've now set the Copy Serialization to
Dynamic.

        Our previous backup product, StorageTek's CAM, had no changing
retries
feature and we never had any problems.   But there is no gurantee TSM
and CAM backup a changing file the same way.

        The TSM Admin User guide warns that this can result in a 'fuzzy
copy'.
Has anyone had a negative experience with fuzzy copies?


--
Scott Walters
Packet Pusher - "The world speaks IP"

Mack Trucks, WHQ        http://www.MackTrucks.com
2100 Mack Boulevard     Ph: 610.709.3728
Allentown, PA 18103     Fx: 610.709.2809