Re: Backing up Oracle using Vertas Backup Exec

Backup Exec has long had the ability to backup all sorts of open files. I use it on a W2K server at home... it backs up plenty of files which W2K's in-built backup utility skips because it doesn't like them being open.

So far, so good. But we return to the usual subject of the last few days here: hot copies of database files are useless, unless you've a mechanism for resolving their internal inconsistency. The mechanism we use for datafiles is to apply redo from the earliest moment they started being copied. How do we know what that 'earliest time' is? Because the headers of the data files tell us... or, rather, they *would* tell us reliably so long as it was the datafile header block that was always, guaranteed, copied *first*.

But O/S copies and agentless Backup Exec don't know anything about the internal structure of datafiles, so which bit they happen to grab first is in the lap of the gods -which is why we have the 'alter tablespace X begin backup' command, which freezes the datafile header, so that whenever the utility finally gets around to copying it, it still tells us the time the datafile started to be copied.

Unless your systems department is issuing that command left right and centre, a Backup Exec backup is going to be of zero use in recovery situations.

With the agent, however, it's all rather different... suddenly Backup Exec understands the internal structure of data files, and can make an intelligent grab for the datafile header as the first thing to copy as it arrives at each file. Works a treat. And rather like RMAN in that respect (which also doesn't need the 'begin backup' technique for the same reasons).

From memory, the Oracle agent is horrendously expensive... but not as expensive as a pile of useless datafiles are going to be one day.

Regards
HJR

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"Robert Bollinger" <robert_bollinger_at_hotmail.com> wrote in message
news:a966437c.0201091056.4656d418_at_posting.google.com...


> Hello -- I am not familiar with Veritas BU Exec, but it seems that our

> Systems department is using it to back up our Oracle databases.  We've

> never done a recovery so the assumption is that everything will be

> okay at recovery time.  That is NOT what I assume, which is why I am

> exploring this issue.

>

> I noticed a number of references to the "Oracle Agent" for BE and

> found that we are NOT using it.  Is the Oracle agent necessary?

>

> Can anyone point me to a good reference for using Backup Exec as the

> primary BU strategy?  Does BE Exec compare to Norton Ghost, or is that

> a different animal altogether?  Is there a dramatic change of

> procedure when using Backup Exec as opposed to doing the usual cold or

> hot backups with Oracle.

>

> Many thanks for your help!  We're getting down to the wire with this

> thing.

>

> Bob Bollinger