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Physical Standby Failover Scenario [message #244067]

Mon, 11 June 2007 09:07

mlgoins
Messages: 116
Registered: March 2007
Location: Denver, CO

Senior Member

In my first FAILOVER test, ALTER DATABASE...FINISH didn't work: I had to use ALTER DATABASE...FINISH SKIP STANDBY LOGFILE. The result is that all of the Standby Redo Logfile content is lost. I'm going to test again, and include the ALTER DATABASE...CANCEL statement first (not sure I did that the last time). If I cannot recover the STANDBY REDO LOG content on FAILOVER, I see NO advantage of using LGWR Transport services compared with ARCH Transport services.

Any experience in failed failover out there? I'm using DG 9.2, with a Primary DB and a Physical Standby DB.

Mike

Ref: (from online documentation)

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
This cancels the normal managed Recovery. To get the Standby
RedoLog Information is still required. Therefore issue this command:

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH;

- If a Standby RedoLog is not used for any reason, then run this one:

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE FINISH SKIP STANDBY LOGFILE;

Please keep in mind that this one causes (Minimal) Data Loss as the latestet information from the down Primary Database is not available anymore.

- Once this is complete (This performs a complete Recovery or incomplete Recovery until the last SCN included in the latest archived Log available at the Standby), you can now make the Standby Database a Primary:

SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY

WARNING: This will only succeed if the correct RECOVER FINISH-statement was issued before. If you forgot the 'SKIP STANDBY LOGFILE' although you have no Standby RedoLogs, the COMMIT to Switchover will fail with the error that more Media Recovery is required here.

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Re: Physical Standby Failover Scenario [message #244077 is a reply to message #244067]

Mon, 11 June 2007 09:50

DreamzZ
Messages: 1666
Registered: May 2007
Location: Dreamzland

Senior Member

Mike

what is the value of your
FAST_START_MTTR_TARGEt parameter?

Do you think this would help full in above scenerio?

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Re: Physical Standby Failover Scenario [message #244083 is a reply to message #244077]

Mon, 11 June 2007 09:59

mlgoins
Messages: 116
Registered: March 2007
Location: Denver, CO

Senior Member

The FAST_START_MTTR_TARGET value is 0 on both databases.

I didn't see any reference to this parameter in the DG 9.2 documentation, but I'll read up on it and see if it might be helpful, thanks!

Mike

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