Re: Suitable backup method for me ?

"Dino Ming" <dinoming_at_hotmail.com> wrote in message news:<absh35$r60$1_at_tenorhorn.hk.dyxnet.com>...
> Dear All,
>
> Can somebody help me to carify which backup method is best for me. ?
>
> I've 1 RS/6000 loaded AIX4.3.3, and which is running an Oracle 8.1.7.2
> + 9iAS. We've 2 newly created tablespaces for our data. And it is
> running under NON-ARCHIVELOG mode..
>
> The box is not too critical, as it can shutdown at night.
>
> Currently, I'm using the exp approach to dump these Tablespaces to a
> file. And back it up into Tape every night.
>
> One of my friend told me that using the exp approach to backup the
> oracle is not suitable for me. So, I'm now confusing... and start to
> find/gather information on using RMAN.
>
> Please share your experience with me.
>
> Rgds,
> Dino
>
> --

Dino,

First point I would make is that running a production database in NON-ARCHIVELOG mode is a bit dangerous, in that you have no way of recovering your database in the event of media failure other than restoring from the last offline backup. If your database is exclusively or predominantly read-only, then this is probably not an issue.

If you continue to operate in NON-ARCHIVELOG mode, then the best way to secure your database is, in addition to doing a full export which secures a LOGICAL backup, to do nightly offline backups, which will secure a PHYSICAL backup. An offline backup involves shutting down the database in NORMAL or IMMEDIATE mode (NOT ABORT) and then making operating system backups of all data files, control files and redo logs.

If you switch to ARCHIVELOG mode then your options are to either backup offline as above or to do online backups, which are done with the database open. Online backups involve putting each tablespace in turn into BACKUP mode, making an operating system backup of the data files associated with the tablespace and then taking the tablespace out of BACKUP mode:

ALTER TABLESPACE MY_TS BEGIN BACKUP; Do O/S backups of data files.....

ALTER TABLESPACE MY_TS END BACKUP; Then you make a backup of the control files:

ALTER DATABASE BACKUP CONTROLFILE TO 'file_spec' REUSE;

Finally I would switch log file a few times to archive off the current redo log:

ALTER SYSTEM SWITCH LOGFILE; Remember that you MUST backup your archived redo logs if doing online backups, as they are your means of recovering the database. In addition, I usually make sure that I keep a copy of the structure of the database by doing an ALTER DATABASE BACKUP CONTROLFILE TO TRACE; and I keep a copy of the parameter file for the database (init<SID>.ora). These last two are not essential, but they make restoring the database a bit less troublesome in some circumstances.

RMAN is Oracle's Recovery Manager and is essentially another way of achieving online backup. It has considerable advantages, but does add another layer of complexity to the understanding of what you are doing.

For better detail on the backup options you need to read a decent manual, but I hope this gives you food for thought anyway.

Regards,
Tim Kearsley
Milton Keynes Council Received on Wed May 15 2002 - 05:08:38 CDT