Re: Differential incremental backups
- From: Guillermo Alan Bort <cicciuxdba@xxxxxxxxx>
- To: william.muriithi@xxxxxxxxxxxxxxxxxxx
- Date: Thu, 18 Mar 2010 10:50:23 -0300
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@xxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx>
> *To*: oracle-l@xxxxxxxxxxxxx <oracle-l@xxxxxxxxxxxxx>
> *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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