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| Re: restore 11g to 19c using rman [message #685722 is a reply to message #685721] |
Mon, 14 March 2022 13:45   |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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Thanks John for the reply.
I just got confused looking at the RMAN compatibility matrix.
Also what do you mean when you say unless you going cross-platform?
Do you mean Migrating using Transportable tablespace on OS with different endian formats
Thanks for clarifying.
Varun
[Updated on: Mon, 14 March 2022 13:50] Report message to a moderator |
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| Re: restore 11g to 19c using rman [message #685724 is a reply to message #685721] |
Mon, 14 March 2022 17:05 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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Hi John,
I want to test it if its really possible.
Our production database on 11g is really huge and full restore wont be possible on test server because of that.
Can I backup spfile or a tablespace from 11g prod and then restore it to 19c test to prove that restore is possible?
Thanks,
Varun
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| Re: restore 11g to 19c using rman [message #685725 is a reply to message #685724] |
Mon, 14 March 2022 18:24 |
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EdStevens
Messages: 1376
Registered: September 2013
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Senior Member |
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Quote:Can I backup spfile or a tablespace from 11g prod and then restore it to 19c test to prove that restore is possible?
No. The database exists as a total unit.
Also note that restoreing a database from an rman backup is a process of rebuilding the physical data files, block by block. That means that if the backup was from an 11g database, the rman restore will rebuild that same 11g database. If you were to rebuild (restore/recover) it running under a 19c home, you would have to immediately follow-up with an upgrade in place.
[Updated on: Mon, 14 March 2022 21:02] Report message to a moderator |
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| Re: restore 11g to 19c using rman [message #685726 is a reply to message #685724] |
Tue, 15 March 2022 02:17 |
John Watson
Messages: 8960
Registered: January 2010
Location: Global Village
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Senior Member |
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varunvir wrote on Mon, 14 March 2022 22:05Hi John,
I want to test it if its really possible.
Our production database on 11g is really huge and full restore wont be possible on test server because of that.
Can I backup spfile or a tablespace from 11g prod and then restore it to 19c test to prove that restore is possible?
Thanks,
Varun Theoretically, yes. When you restore and recover, use the SKIP TABLESPACE clause to exclude all except SYSTEM, SYSAUX, and UNDO. However, I have found that when you start stacking up less commonly used features you may have problems.
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| Re: restore 11g to 19c using rman [message #685728 is a reply to message #685726] |
Tue, 15 March 2022 08:19 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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John,
My client has backups for last 7 years on 11g that they want to restore on 19c few times a year.
Is it possible to use RMAN backups for 11g version to restore directly into 19c?
Thanks,
Varum
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| Re: restore 11g to 19c using rman [message #685733 is a reply to message #685729] |
Tue, 15 March 2022 10:24 |
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EdStevens
Messages: 1376
Registered: September 2013
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Senior Member |
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varunvir wrote on Tue, 15 March 2022 08:22Thanks Ed.
So once i upgraded to 19c. Can I use backups taken on 11g to be restored directly on 19c or would it overwrite 11g data-dictionary?
Thanks,
Varun
LIke I said, it is physically rebuilding the entire database. That includes the data dictionary, which is nothing more than some system-maintained tables within the database. And there is potentially more to an upgrade than just the data dictionary. While I have had no reason to see it first hand, I'd strongly suspect that there are also changes to the file structures themselves, particularly information in the file header blocks.
When you restore from an rman backup, you are not "restoring to" another database. You are rebuilding the original database that was backed up. Every time. So if you back up an 11g database and restore it under a 19c home, you have just rebuilt an 11g database. Since you are running it under a 19c home, you will need to upgrade it to 19c. Repeat the restore and you have overwritten your 19c database with a physical copy of the original 11g database, so you again have an 11g that needs to be upgraded.
When rman takes a backup of a database, it is copying the database files file-block by file-block. The backup pieces (files) are not merely OS-level copies of the database files. When it does a restore operation, it is rebuilding those files, block by block. It doesn't know or care what is in those blocks. It only cares that they go back into files in the same position as they were originally. Imagine looking at a stone wall. Imagine having a method of duplicating each and every stone in the wall, along with information regarding the exact position of that stone within the wall. Now, take that load of duplicate stones to another field and re-assemble them according to the placement information. Now, you have an exact duplication of the original wall.
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| Restore tablespace [message #685746 is a reply to message #685720] |
Wed, 16 March 2022 14:39 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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Hi Experts,
I have 35 tbs data on 11g that I want to restore to 19c.
I am doing this exercise for testing purpose to see that restore is possible from 11g to 19c.
Can I take backup of one tablespace instead of whole database and restore it to 19c, Or Does it have to be full backup since I am doing it for testing purpose.
Thanks,
Varun
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| Re: Restore tablespace [message #685748 is a reply to message #685746] |
Wed, 16 March 2022 15:04 |
John Watson
Messages: 8960
Registered: January 2010
Location: Global Village
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Senior Member |
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You referred to a client,Quote:My client has backups for last 7 years on 11g that they want to restore on 19c few times a year.
Are you charging for this service? If so, perhaps you should attend an Oracle Backup And Recovery course because you do seem to be missing a few basic concepts. Ed explained some of them, I tried too, but you still do not seem to appreciate some of the basics.
Can you define the difference between the instance and the database and the Oracle Home? Your use of phrases such as "...Can I take backup of one tablespace instead of whole database and restore it to 19c..." is a bit worrying. And have you read this yet:
https://docs.oracle.com/en/database/oracle/oracle-database/19/bradv/index.html
If not, you had better do so now.
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| Re: Restore tablespace [message #685749 is a reply to message #685746] |
Wed, 16 March 2022 15:07 |
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EdStevens
Messages: 1376
Registered: September 2013
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Senior Member |
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varunvir wrote on Wed, 16 March 2022 14:39Hi Experts,
I have 35 tbs data on 11g that I want to restore to 19c.
I am doing this exercise for testing purpose to see that restore is possible from 11g to 19c.
Can I take backup of one tablespace instead of whole database and restore it to 19c, Or Does it have to be full backup since I am doing it for testing purpose.
Thanks,
Varun
Haven't you already asked that question?
Now, recall what I said earlier about "changes to the file structures themselves, particularly information in the file header blocks. " So, suppose you could do that, using the 'skip tablespace' already mentioned. Now you have some files with 11g block headers and some with 19c block headers. Sounds like a recipe for all kinds of problems.
Recall what I already said about the fact that a restore operation builds the database from scratch - that it does not 'recover into an existing database'? Perhaps I should have also pointed out that rman is simply rebuilding the physical files in the specified location. He doesn't know or care if the database is going to be managed by the proper version and patch level of the rdbms software.
If you are trying to do a proof of concept and are stymied by the fact that your 11g production database is so large, why not create a smaller 11g test database, and work with that? What is the real ultimate goal of this exercise?
[Updated on: Wed, 16 March 2022 15:08] Report message to a moderator |
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| Re: Restore tablespace [message #685750 is a reply to message #685749] |
Wed, 16 March 2022 16:27 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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Thanks Ed,
Thanks for claryifying.
Yes I agree that we can't just restore tablespace since from 11G TO 19c as you explained that RMAN rebuilds it from scratch.
I just wanted to confirm again.
We have a database 35 tbs of backups taken from 11g database that vendor is not gonna provide support 11g for since all the servers have been upgraded to 19c.
The client wants to restore that 35tbs backups once in six months. We could use dump utility for that after restoring that data to 11g(take the dump from that) but that takes long time coz of the size of the database.
So we are thinking to do RMAN restore instead from that 11g bacupk and restore directly to 19c and then do an immediate upgrade everytime we do that.
We want to do this exercise to show the test case to DBA'S working on this since DBA'S working on this say that RMAN restore is not possible between 11g and 19c.
Thanks,
Varun
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| Re: Restore tablespace [message #685751 is a reply to message #685748] |
Wed, 16 March 2022 16:58 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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John,
I do understand these basics that you mentioned.
Its not a realtime migration but just for testing purpose.
But I will definitely go through the document if thats your advice.
Thanks for being a mentor and helping me be humble.
-Varun
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| Re: Restore tablespace [message #685759 is a reply to message #685756] |
Fri, 18 March 2022 00:26 |
varunvir
Messages: 389
Registered: November 2007
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Senior Member |
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Actually I am DBA here and I just recently got into this team.
I am not supporting this particular project and I don't really have access yet to any of the dbs either
The DBA's working on this particular prod server have been telling that it's not compatible(11g to 19c).
I have been advising that it is compatible and Thanks you for guiding me that how is it possible.
My Manager wants to do POC and show the test case to DBA'S working on this.
Thanks a lot Ed.
-Varun
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