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RE: re BCV / SnapShot / SnapClone and the ALTER SYSTEM

From: John Kanagaraj <>
Date: Mon, 12 Jan 2004 16:59:26 -0800
Message-ID: <>


I apologize - I didn't want to imply that you were not aware of the way RMAN works. However, I am not sure I got my point across on the Hot backup issue, so here goes...

You should not take a backup of a BCV mirror _without_ putting the whole database in Hot backup, even if you suspend all I/O using SUSPEND. AFAIK, the SUSPEND command was provided to enable an 'instance recoverable' database copy and NOT a day-to-day backup copy. In other words, a copy taken after a successful SUSPEND can be restored and started up, in which case an _instance_ recovery is done. The issue is that you cannot perform _media_ recovery to this copy to bring it up a particular point in time, which is the whole point of a backup...

The way I see it, a DBA can use the SUSPEND command to backup a Development/Test database, which would not demand a point-in-time recovery requirement but require a end-of-day backup without having to shut it down. The other use of couse is to reduce or even eliminate IO activity to the BCV while the split occcurs. The split can take quite a while to complete if a session performs heavy writing - a Hash join writing to TEMP can very quickly overwhelme the Write cache of a SAN and delay the split.

I found ML Note:91059.1 useful in understanding the SUSPEND command...

John Kanagaraj
DB Soft Inc
Phone: 408-970-7002 (W)

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>-----Original Message-----
>From: Mladen Gogala []
>Sent: Monday, January 12, 2004 11:34 AM
>To: Multiple recipients of list ORACLE-L
>Subject: Re: re BCV / SnapShot / SnapClone and the ALTER SYSTEM
>John, I know that fro RMAN tablespaces need not be in hot backup
>mode. The trick with susspend is quick & dirty way of achieving
>the same effect as with the cold backup, without bringing the
>database down. No RMAN involved.

Please see the official ORACLE-L FAQ:
Author: John Kanagaraj

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Received on Mon Jan 12 2004 - 18:59:26 CST

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