Re: RMAN question
- From: "Jared Still" <jkstill@xxxxxxxxx>
- To: joseph.armstrong-champ@xxxxxxxxx
- Date: Mon, 17 Sep 2007 19:04:40 -0700
I'll get on my soapbox for this one.
Using RMAN without a Repository Catalog in a separate database
(on a separate server!) is a mistake.
Oracle would have you believe that RMAN is just as robust with
CF only as it is with a repository.
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From ML Note 360416.1 on 10g
Except for stored scripts, all of RMAN's features work equally well with or
without a recovery catalog.[1] <#_ftn1>
[1] <#_ftnref1> Don't believe it.
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Next see:
ML Note 304305.1 Limitations of TSPITR Without a Recovery Catalog
----------------------
Database incarnations require an external recovery catalog.
----------------------
retrieving the DBID of a database is easy with a recovery catalog:
select * from rc_database where lower(name) = 'orcl'
Why would you need the DBID?
To recover an autobackup controlfile.
Of course with a recovery catalog, you don't need to look up the DBID, as
RMAN does it for you.
Without a recovery catalog, you must know the DBID to recover an autobackup
controlfile.
------------------------------
Experience with different recovery scenarios has shown the
a recovery catalog makes many recoveries much easier.
Many difficult recovery scenarios can be done with a CF only,
but the expense in doing so comes at recovery time when you
are trying to determine what to restore, and how to do the recovery
with a CF only.
The restoration of autobackup controlfiles is one example.
--------------------------------
A recovery catalog allows you to maintain backup data for long periods of
time.
Using Netbackup as an example, even after backup pieces have been removed
from the NBU catalog and the tapes have gone offsite, the recovery catalog
can
retain that information.
Once the tapes have been re-cataloged in NBU, there's nothing else to do in
RMAN
except perform the recovery. This assumes that you do not run CROSSCHECK to
sync up RMAN with the NBU catalog.
Leaving that much data in a controlfile can make for some rather large CF's,
but no
problems for a recovery catalog.
Why leave backup data in a recovery catalog for long periods of time?
If you delete the information a backup piece from the catalog, putting it
back
in is a bit of a pain. The backup piece must be on disk to recatalog it.
So, most things are possible with CF only, but you may not want to rely
exclusively on a CF for recovery.
... stepping of the soapbox now
--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
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