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Re: Backup & Restore

From: DA Morgan <>
Date: Fri, 21 Sep 2007 09:20:35 -0700
Message-ID: <>

Ravip via wrote:

> Hi Brian,
> From your feedback I have arrived the following backup strategy.
> Level 0 backup every week.
> Level 1 backup daily.
> Retains the backup for every 4 weeks and it will be a cycle.
> As my intention is to not loose any data but with present setup I didn't
> configured for log shipping or data guard.
> Please have your feedback again on this.
> Thank You.
> Brian Peasland wrote:

>>> Hi Brian,
>> [quoted text clipped - 10 lines]
>>> Thank You.
>> You will not need the archived redo logs from prior to the incremental
>> backup. However, if the last incremental backup was unusable for some
>> reason, you would need the archvied redo logs since the previous
>> incremental backup. Just to be safe, I keep the archived redo logs since
>> the previous incremental level 0. And I keep at least 3 level 0 backups
>> on hand. So if I generate a level 0 once a week, I'll have 3 weeks worth
>> of backups on hand. To make sure that I can use any of those backups, I
>> keep the archived redo logs for the last 3 weeks.
>> Keeping more than one generation of your backups is an old practice. The
>> most recent backup is generation 0. The backup before that is generation
>> -1. You may have generation -2 and maybe generation -3, depending on
>> your retention policy.
>> The reason to keep multiple generations is that backups are often stored
>> on tape media and tape media can fail. If there is only one backup and
>> that tape fails, the safety net is lost. But by having more than one
>> generation, we ensure we can get access to at least some of the data.
>> The other reason to keep multiple generations around is that one may
>> discover a problem (i.e. bad data) and that problem is in the backup.
>> One may occasionally desire to restore before that data became a
>> problem. This is hard to do with only one generation. Multiple
>> generations do not guarantee success here either.
>> In your reply, you stated "Obviously I'm not in a position to lose data
>> generated in last minute as well.". This makes me ask...are you doing
>> some sort of log shipping? Are you ensuring that your logs switch and
>> get archived at least once a minute? If not, then you may be at risk of
>> losing more than one minute's worth of data. Have you looked at Data
>> Guard in your data protection strategy?
>> HTH,
>> Brian

Good start.
Did you do the following?

alter database force logging;
alter database add supplemental log data; alter database flashback on;
alter system set DB_FLASHBACK_RETENTION_TARGET = 2880; -- or other value

If you have EE I would give serious consideration to using Physical Data Guard in Maximum Availability mode.

Daniel A. Morgan
University of Washington (replace x with u to respond)
Puget Sound Oracle Users Group
Received on Fri Sep 21 2007 - 11:20:35 CDT

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