Networker

Re: [Networker] Why Oracle incremental backup is as large as a full?

2007-05-03 10:57:16
Subject: Re: [Networker] Why Oracle incremental backup is as large as a full?
From: George Sinclair <George.Sinclair AT NOAA DOT GOV>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Thu, 3 May 2007 10:57:01 -0400
All very interesting responses. Thanks! Yes, indeed, it could have been the fact that we were not running a level 0 that was causing this mischief, but I read somewhere that if you run a level 1 cumulative , and it does not have a level 0 to build on then it will force one, which I would think would then allow any subsequent level 1 backups to run as normal, but maybe not? In other words, maybe unless you overtly run a level 0 then any following level 1 cumulative incremental
will not run as expected?

We, too, have noticed that these incrementals take as long to run as level 0 backups, but they are very fast to recover from. I notice, for example, that when recovering from a full (level 0) backup of say 4 save sets that NetWorker will recover the first one, and then there will be a time lapse (maybe 20-30 min) before it will recover the second one. It does this for each one recovered. I suspect that Oracle is doing something with the recovered data during this time or reorganizing the closet or whatever. However, when recovering the subsequent incremental, it only takes minutes to run, and there is virtually
no lag time between the recovered save sets.

I will ask our DBA about the block change tracking, but I thought ORacle 10g used this
by default? Must it be overtly turned on?

George

Uwe Weber wrote:
Preston de Guise schrieb:

I always followed their instructions, and always got proper
full+"incremental" backups. One thing of course is that while the
"incremental" is usually much smaller than the full, many of my
customers have found that it takes almost as long as the full, and is
more intensive on database processing than the full, due to the
tablespace scans that have to be done.
If you are backing up Oracle 10, you could ask your
DBA to enable Block Change tracking. This will
speed up incrementals a lot.
Regards,
uwe

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