Re: Oracle + LVM = Mirrored Backups?

On Fri, 19 Nov 1999 02:21:58 GMT, fpuhan_at_my-deja.com wrote:

>During a recent discussion with a tech from Hewlett Packard, I was
>informed that it is possible to perform backups on VLDBs with a minimum
>of downtime by using LVM (Logical Volume Manager) to create mirrored
>copies of Oracle's data files, then by "breaking" the mirror, backup the
>mirror copies of the data files, and the re-sync the mirror once the
>backup is complete. The total downtime I'm told is in the minutes, if
>not seconds.

When I have seen this done before, it has been in conjuction with an EMC with BCVs or an XP256 with Business Copy. Any of the vendors (HP, Oracle, EMC) will be glad to work with on implementing this solution. It does work quite well, not just for backup, but for testing as well. (Resynching refreshes the test database for another test).

The basic premise is that the breaking of the mirror is the equivalent of doing the tape backup. So, you mark your redo logs, go into full backup mode, break the mirror, exit backup mode, flush your logs. Now you can back up the mirror, the archived logs, and your control files at your leisure. When the back up is done, resynch the mirror, and you are ready for the next backup.

For some businesses, it works best to leave the mirror broken until just before the backup. That way if there is a crash, recovery is done by a reverse synch and roll forward, no need to restore the tapes. The tapes are now just for catastrophic failure. Received on Thu Nov 18 1999 - 22:11:49 CST