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Re: Backup during no activity

From: <Kenneth>
Date: Thu, 08 Jun 2006 20:45:09 GMT
Message-ID: <448886a6.4155750@news.inet.tele.dk>


On Thu, 8 Jun 2006 21:55:13 +0200, "astalavista" <nobody_at_nowhere.com> wrote:

>Hi,
>
>Why I can't backup my (small) database
>with a copy of all files (spfile, datafile, control, online redolog)
>when there is no activity on the database ?
>Any of these files are modified when there no activity ?
>( something like a heartbeat ?)
>
>Thanks for your lights ....

The short explaination is that Oracle does not support flat-file backup of a running database. Which itself is reason enough.

The long explaination :

Even when there is no "activity" (which I translate into "user activity"), Oracle background processes still hold locks on the DB files. So online backup not supported.

Furthermore, the many optimization features of Oracle may hold the db files in a "fuzzy" state, even if there is no user activity *right now*. Though Oracle is capable of recovering its files from an instance crash, it still requires all files to be fully syncronized *in time*.
Imagine you backup the datafiles and 3 seconds later backup the redo log files. They are simply out of sync, because Oracle may have written to the redo logs during the 3 seconds even if there is no user activity. And recovery will not be possible.

Received on Thu Jun 08 2006 - 15:45:09 CDT

Original text of this message

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