DB backups seems to work ok and I have run them alongside clients
sessions. This how I understand it works, similar to and Oracle backup
really.
The DB backup seems to 'freeze' database activity even if client sessions
are active and generates its image to backup. While the database activity
is frozen and the database backup running the transactions generated by
the client are written to the Logvolumes instead of Database volumes. When
the backup complete these Log volume transactions are sync'd back binto
the database.
Some considerations to here are that your DB backup is out of date as
soon as it completes if it backed up while clients were active.
Should you need to recover your DB you will be losing data straight away.
Roll forward recovery mode may be an option here plus the various ways of
running incrementals etc so you could look into that option.
You must have sufficient recovery log space available to take all the
client transactions whilst the backup is running. You can monitor how much
log is used between dbbackups by reset log consumption statistics.
John
"Sam Sheppard" <SHS AT sddpc.sannet DOT gov>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT vm.marist DOT edu>
06-Nov-2002 17:08
Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT vm.marist DOT edu>
To: ADSM-L
cc:
Subject: Safe to backup DB while c
---------------------------- Top of message ----------------------------
>>--> 11-06-02 09:06 S.SHEPPARD (SHS) Safe to backup DB while c
I have never heard of or seen any restrictions or problems with backing
up the DB while backups are running.
Sam Sheppard
San Diego Data Processing Corp.
(858)-581-9668
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---------------------------- Top of message ----------------------------
>>--> 11-06-02 07:48 ..NETMAIL (001) Safe to backup DB while c
Date: Wed, 6 Nov 2002 10:40:17 -0500
From: "Matt Simpson" <msimpson AT UKY DOT EDU>
Subject: Safe to backup DB while client backups running?
To: ADSM-L AT VM.MARIST DOT EDU
_________________________________Top_of_Message_________________________________
We're trying, usually in vain, to get our TSM environment under
control. We have daily scripts that perform backups of our database,
one onsite and one offsite. The scripts check to see if any backup
sessions are active, and if they are, they reschedule themselves to
try again in 10 minutes.
It's getting more and more difficult to find any time during the day
when backups aren't running. We keep spreading backup schedules out
to try to get stuff to run successfully. Our offsite tapes are
supposed to be sent offsite by 8 AM, but sometimes they're not
getting completed until mid-afternoon.
Ideally, I know it would be safer to backup the database when it's
not being updated by backup processes. But it seems like there's no
way we're going to be able to reach Nirvana. If I want my DB backups
to run at any kind of predictable time, it looks like we're going to
have to allow them to run while client backups are running. Am I
setting myself up for major trouble if I do that?
Actually, I'm not 100% sure it's not already happening. I know we
don't start the database backup if any client backup sessions are
active. But I'm not sure if there's anything in place that prevents
a client backup from starting after the DB backup starts. If that's
true, are we just wasting time spinning our wheels waiting for a
window when no backups are running to start the DB backup?
--
Matt Simpson -- OS/390 Support
219 McVey Hall -- (859) 257-2900 x300
University Of Kentucky, Lexington, KY 40506
<mailto:msimpson AT uky DOT edu>
mainframe -- An obsolete device still used by thousands of obsolete
companies serving billions of obsolete customers and making huge obsolete
profits for their obsolete shareholders. And this year's run twice as
fast
as last year's.
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