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RMAN Confusion [message #321912] Wed, 21 May 2008 15:59 Go to next message
lotusdeva
Messages: 198
Registered: March 2005
Senior Member
Hello --

I was wondering if someone can remove the following confusion about RMAN. We have many databases, which we would like to back up using RMAN. My understanding is that if we have allot of databases it is best to use recovery catalog, rather then store backup information in the control file of the target database. It is also my understanding that RMAN with its recovery catalog should be preferably on a separate from target database(s) server. However, "Oracle Database 10g RMAN Backup & Recovery" book states that it is preferable to run RMAN from the target database's ORACLE_HOME rather then remotely. So if we have 10 databases and we don't go with a recovery catalog on a separate server, we would configure RMAN locally on each of the 10 databases? This doesn't make sense. This book also states that the reason for why you would want to run RMAN locally (in target database's ORACLE_HOME) is because it is simpler this way, you don't need to add password file nor modify tnsmaes.ora. In fact the book states the following:

Running RMAN locally from each target database is really the only way to manage a large enterprise with hundreds or thousands of database targets. Because of RMAN's legendary compatibility headaches, keeping the rman.exe bundled tightly to the target database will save you time in the long run.

Someone please explain...If we have over 50 databases, isn't it better to have a recovery catalog that would manage all of them on the separate server, rahter then running RMAN locally from each of these 50 databases? Thank you

[Updated on: Wed, 21 May 2008 16:03]

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Re: RMAN Confusion [message #321925 is a reply to message #321912] Wed, 21 May 2008 18:56 Go to previous messageGo to next message
skempins
Messages: 16
Registered: June 2005
Location: Florida
Junior Member

That does sound a bit confusing. You should be able to use a single database for the RMAN catalog. I, personally, think it is advantageous to have only one RMAN catalog database.

Although, here are a couple of reasons I can think of to consider more than one:
1. If your databases are spread physically across a WAN, you may want more than one to not worry about network latency.
2. If the databases vary by version, it will probably be simpler to have one for each database version. This is probably where the "...legendary compatiblity headaches..." statement comes from. There is a MetaLink doc on rman catalog version compatibility, but I cannot find it at the moment.

Keep in mind that the RMAN Recovery Catalog is just a database schema that the rman executable is designed to work with. That can be a single schema in a single database that is used by every rman "connect catalog..." statement, or more than one schema or database depending on reasons I mentioned above.

I use one RMAN catalog to manage all of our 25 databases which are either 10g R1 or R2. Hopefully I have helped some and not just rambled on.
Re: RMAN Confusion [message #321941 is a reply to message #321925] Wed, 21 May 2008 20:54 Go to previous messageGo to next message
lotusdeva
Messages: 198
Registered: March 2005
Senior Member
I guess I am mostly confused about the location of RMAN executable, which this book is describing. When they say about running RMAN locally versus remotely. If I am running RMAN locally for my 20 databases, that means that I would have 20 RMAN executables? Then there is no point in recovery catalog, correct? If, on the other side, we are running RMAN remotely then the only way to do so is by the use of the recovery catalog, which in a way centralizes the whole thing? Or am I confusing recovery catalog with network topology (remote vs local)? Thank you for the answer!

[Updated on: Wed, 21 May 2008 21:00]

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Re: RMAN Confusion [message #321943 is a reply to message #321912] Wed, 21 May 2008 21:11 Go to previous messageGo to next message
BlackSwan
Messages: 25042
Registered: January 2009
Location: SoCal
Senior Member
>that means that I would have 20 RMAN executables
Yes, you'll have 20 RMAN executables, 20 Oracle executables, 20 exp executables, 20 imp executables, 20 sqlplus executables, etc.

So, exactly what is the point about having 1 set of execuatbles for every RDBMS system.
You just don't share executable across the network.

This reality has NOTHING to do with 1 or more Recovery Catalogs.
Re: RMAN Confusion [message #321944 is a reply to message #321943] Wed, 21 May 2008 21:17 Go to previous message
lotusdeva
Messages: 198
Registered: March 2005
Senior Member
I think I got it. thank you!

[Updated on: Wed, 21 May 2008 22:26]

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