Re: Differential incremental backups

From: Guillermo Alan Bort <cicciuxdba_at_gmail.com>
Date: Thu, 18 Mar 2010 10:50:23 -0300
Message-ID: <172762181003180650r1da00fc8w5fbb845566f6d4ee_at_mail.gmail.com>



According to Oracle Courseware (it's been a while, but I think I remember it right). There are Full Backups and Incremental Backups. Full Backups take the entire database, Incremental backups have different levels. Level 0 Incremental Backup: Takes the entire database (works just like a full backup, but is used for base point to level 1 and 2 incremental backups).
Level 1 Incremental Backup: backs up all blocks changed after the most recent incremental backup at level 1 or 0 Level 2 Incremental Backup (differential): backs up all blocks changed after the most recent incremental backup at level 0

These are executed using the 'INCREMENTAL LEVEL 0|1|2' in the RMAN BACKUP clause.

For level 1 and 2 backups, having block_change_tracking enable significantly speeds up the backup process. This also requires backup optimization to be on.

Now, as to you REAL question: Will I be able to apply backups up to Wednesday night SCN and open the database ?

What you want to do is called a Point in Time Recovery (PITR), this is possible both with Full backup and with any incremental backup strategy.

Example 1:
Level 0 on saturday
Level 1 sunday, monday, wednesday and friday. Level 2 on Tuesday and Thursday.

On Friday you want to recover the database to wednesday night's SCN. You run the following command:
NLS_DATE_FORMAT='yyyy-mm-dd:hh24:mi:ss'
run {
set until time '2010-03-17:23:59:59'
restore database;
recover database;
alter database open resetlogs;
}

RMAN will automatically restore the saturday Level 0 backup, Tuesday Level 2 backup and Wednesday Level 1 backup, plus all archivelogs since the start of Wednesday Level 1 backup up until the requested time, and will perform the recovery accordingly.

Example 2:
Level 0 on saturday
Level 1 sunday to friday (finishes before midnight)

On Friday you want to recover the database to wednesday night's SCN. You run the following command:
NLS_DATE_FORMAT='yyyy-mm-dd:hh24:mi:ss'
run {
set until time '2010-03-17:23:59:59'
restore database;
recover database;
alter database open resetlogs;
}

RMAN will automatically restore the saturday Level 0 backup and all Level 1 backups until Wednesday plus all archivelogs needed. and will perform the recovery accordingly.

hth
Alan.-

On Thu, Mar 18, 2010 at 10:05 AM, William Muriithi < william.muriithi_at_epicadvertising.com> wrote:

> First, you said differential incremental backup. I believe differential and
> incremental are exclusive to each other if I am not wrong.
>
> Now assuming incremental, you use the monday full backup and all
> incrementals up to Thursday.
>
> If its differential, you use the full backup and the last differential
> backup, which is Thursday
>
> ------------------------------
> *From*: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>
> *To*: oracle-l_at_freelists.org <oracle-l_at_freelists.org>
> *Sent*: Wed Mar 17 23:57:28 2010
> *Subject*: Differential incremental backups
>
> Hello
>
> I take a base backup on Sunday and take differential incremental backups
> every night and I want to perform recovery on Friday. Will I be able
> to apply backups up to Wednesday night SCN and open the database ? Or will
> I be forced to apply all the incremental backups upto Thursday night before
> I can do open reset logs?
> Orlando.
>
>
>

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Received on Thu Mar 18 2010 - 08:50:23 CDT

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