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RMAN Duplication for Migration and Archived Logs

From: Don Seiler <>
Date: Wed, 1 Aug 2007 14:45:07 -0500
Message-ID: <>

OK here it is. Currently we're on Oracle on 32-bit RHEL 3. We're going to be migrating to the same version ( on a 64-bit RHEL 4 box.

I've done this migration plenty of times to create development instances. However, in the case of the actual production migration, we have the question of downtime. My production-to-development duplications are currently taking 10 hours, in there I use the UNTIL TIME parameter to tell it to do the PITR. I've been given an 12-hour overnight downtime window (10 PM Saturday to 10 AM Sunday).

I'm wondering if I can minimize the downtime by starting the duplication earlier while the production database is still running.

Here is our current backup scenario:
* Full backup Saturday evenings to disk

This is the crazy scheme I've been concocting in my head:

  1. Start the RMAN duplication at, say 3 PM Saturday, specifying UNTIL TIME of 10 PM that night.
  2. While this is going on, new transactions are made (none of them are NOLOGGING) in the current production database. Archived redo logs are generated, backed up and rsynced throughout the day.
  3. At 10 PM, change the listener config in the current production box to only allow the auxiliary server to connect, and manually kick all other connections.
  4. After that, force 3-4 log switches, call the script to back them up.
  5. Call the script to rsync.
  6. Assuming that RMAN won't need them by this point (only 7 hours into a 10-hour restore/recovery), we're golden.

Obviously the big "IFs" are:
1. Will RMAN let me specify UNTIL TIME into the future? e.g. saying UNTIL TIME of 10 PM when it is only 3 PM. 2. Will RMAN need those backup pieces on local disk before it begins duplication? I'm assuming it doesn't since I've found out that pieces are missing 8 hours into a duplication.

If anyone can tell me if this is a crackpot scheme that just might work, or simply not possible with rman, I'd appreciate it. Worst case scenario is that I perform the restore/recovery completely within the downtime window.

Don Seiler
Received on Wed Aug 01 2007 - 14:45:07 CDT

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