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Re: Using RMAN

From: Jay Hostetter <jhostetter_at_decommunications.com>
Date: Thu, 17 Jan 2002 12:11:23 -0800
Message-ID: <F001.003F31E3.20020117112523@fatcity.com>

I have gone through this process. We used to backup to disk using scripts as described in Velpuri's book. We now use RMAN to backup to disk. Your backups will be faster and smaller in size, because RMAN will skip unused blocks and it also allows you to specify mutilple channels. I can backup a 70 Gb database in about 60 to 90 minutes. Here is a sample script:

run
{
allocate channel ch1 type disk format '/bkup9/oracle/%d/full_s%s_p%p_%t'; allocate channel ch2 type disk format '/bkup3/oracle/%d/full_s%s_p%p_%t'; set limit channel ch1 kbytes=1000000; # Limit sets to 1 Gb. set limit channel ch2 kbytes=1000000;
backup full database
 tag='daily_full_backup';
allocate channel ch3 type disk format '/bkup3/oracle/%d/arc_s%s_p%p_%t'; set limit channel ch3 kbytes=1000000;
backup (archivelog until time 'sysdate-1/24' delete input

        channel ch3
       );

}

I do archivelog backups with a separate command, because RMAN can be a bit touchy when it comes to archivelogs. If none exist for the time specified, then the backup will fail. This way my database backup will be successful if there is a problem with the archivelog backup.

I would skip the incremental stuff. Just do full backups unless you are talking huge databases.

To tell RMAN what backup files are available on disk, prior to a restore, run this command:

# Check which backups are available on disk. allocate channel for maintenance type disk; crosscheck backup;
release channel;

or this one if you are in noarchivelog mode:

# Check which backups are available on disk. allocate channel for maintenance type disk; crosscheck backup of database;
crosscheck backup of controlfile;
release channel;

Jay Hostetter
Oracle DBA
D. & E. Communications
Ephrata, PA USA

>>> sona_us_at_hotmail.com 01/17/02 12:45PM >>>
See currently we are using Unix scripts to do our hot backups .We take the backup on disk and everynight after the disk backup we copy the backup on tape using Veritas Net Backup.
Presently we keep 2 days worth of backups on the disk and 3 days of archive logs.That means at any point in time i have the last 2 days backup on disk (just for fatster recovery so that we can aviod going to tapes in case of a failure).
Now if we start using RMAN ,we would be taking hot backups (mostly using increamental strategy) using RMAN.So for e.g. we start on say sunday taking an incremental level 0 backup on disk.RMAN only remmbers the disk backup ...right???? Note that we will also be copying the backups on tape but that will be independent of RMAN since it is not done using RMAN. Say the next 3 days of the week ,we do increamental level 1 backups .On the 3 rd day (i.e. Wednesday) i would have only Monday's and Tuesdays' backup on disk (which are the inceemental llevel 1 backups since the whole ideas is to keep last 2 days backup om disk).
So if we have a failure on Wednesday then RMAN would look for the incremental level 0 backup of Sunday on the disk but that backup is not present on the disk now.
I hope i have cleared it up enough.
Now my question is can we maintain the same policy of keeping 2 days backup on disk by using RMAN.
What kind of backup strategies do RMAN users follow? Are RMAN backups usually taken on tape directly ? Is it faster to take backups on tape rather on disk while using RMAN?

Could RMAN users share their backup/recovery strategies ,please.

TIA

> If you are using a recovery catalog then rman keeps track of everything
> there.  He knows if you've been naughty, he know if you've been nice, he
> knows....OOOPS I got carried away.  But  when you do a restore using rman
he
> will tell you what backup sets you will need.
>
> Ruth
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Wednesday, January 16, 2002 6:20 PM
>
>
> Hi
> Currently we are using Unix scripts to do backups.We keep last 2 days of
> backups on the disk and also take the backups on tape daily.
> We are planning to use RMAN for backups and would like to maintain the the
> same policy of 2 days backup on disk and daily tape backups.
> Is it possible to implement this using RMAN? Which backup will RMAN
remember
> (while restore) the disk backup or the tape backup? > If we try to use the incremental strategy ,then how would RMAN remember the
> last incremental level 0 backup ? It will not be present on disk since we
> only keep the last 2 days backup on it.
> How do i use RMAN to do restore/recovery in this case?
>
>
> I heard that taking backups on tape is faster than on disk when using
RMAN?
> Is it true?
>
> Could RMAN users share their backup/recovery  strategies ,please.
>
> TIA
>
>
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com 
> --
> Author: Ruth Gramolini
>   INET: rgramolini_at_tax.state.vt.us 
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com 
-- 
Author: Sona
  INET: sona_us_at_hotmail.com 

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--
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--
Author: Jay Hostetter
  INET: jhostetter_at_decommunications.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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Received on Thu Jan 17 2002 - 14:11:23 CST

Original text of this message

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