Re: ORACLE 8.0.5 Backuping Datawarehouses

Try using an export with the direct flag set to Y and piping the output to Tar and GZip. If you have the proper drivers for you tape unit, you should be able to direct the output directly to your tape library without writing anything to disk. This mechanism by itself is fairly inflexible, but it produces the smallest and fastest output for backup without producing any log data. If you have room to write to disk, then you won't have to rely on the tape.

Given the size of your data, perform this operation on chunks of tables until the granularity is acceptable.

I have had 50Gb of data compress down to less than 500MB using direct exports and external compression. You should be able to compress 500GB of data so that it will fit on a single DLT tape with room to spare.

You may have to create clones of your tables in order to get a proper backup of tables that must be available 24/7, that is copy a set of tables, then export the clones and drop the clones. If your frequency of updates is low, you may get away with a direct export on the original tables.

Direct backups of your data files wastes an incredible amount of storage. Exports can compress free space, coalesce extents, and can compress the data itself.

For restores, exports work well because you can import to a new schema and simply copy the data over once it has been verified. If you lose your control and init.ora files, you can still restore from an export by simply re-creating the schemas/users and importing the data. A cold backup of data files also requires you to have the original control files and init.ora. Otherwise, your restore may fail.

Traditional back-up managers (RMAN and other compatibal backup agents) add additional control, but they also waste space and take longer.

Christopher Weiss
Professional Services Division
Compuware Corporation

<sparik_at_my-deja.com> wrote in message news:7n9hjl$jpi$1_at_nnrp1.deja.com...
> Has anyone used RMAN with a Datawarehouse
> environment under unix. We have about 500Gb of
> data that needs to be backed up. The database
> operates in th 24x7 environment. Traditionally we
> have always used Cold Backups with Disk Cloning.
> Hotbackup would generate hugh redo logs. I would
> be interested to know what backup types people in
> a similar environment such as ours use.
>
>
> Sanjeev Parikh
>
>
> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.
Received on Fri Jul 23 1999 - 08:47:44 CDT