Re: Can Anyone Explain ...

On Jan 29, 6:50 pm, "Dereck L. Dietz" <diet..._at_ameritech.net> wrote:
> Why the "DBA" in charge of a database would not use RMAN to back up a
> database? It currently takes nearly 24 hours each weekend to do a cold
> backup.
>
> When I questioned why about all the answer I got was that the RMAN catalog
> "wasn't installed". I also wasn't able to find out what it was he was using
> to do the backup of an over 2,000 GB data warehouse.
>
> Also, can anyone confirm/deny whether he has valid points in not using
> Oracle ASM when we are experiencing bad I/O throughput. His "reasons" were
> that he'd have to shut the database down in order to convert to ASM and he
> had a problem with raw devices.
>
> The I/O throughput problem we've been having is that there are 6 data
> tablespaces, 5 indexes tablespaces and 3 temporary tablespaces (and their
> associated physical files) all on the same drive causing massive waits if
> more than a few people start querying data.

RMAN is great, but it does have it's limits. Particularly in a Data Warehouse. This does not mean it shouldn't be used. It does mean that the DBA might need to be creative. Unfortunately, when it comes to backup and recovery, creativity isn't always the best solution. I have setup RMAN to hotbackup active Warehouses in Archive mode. Getting in Archive mode was the first issue. The second is Nologging direct path inserts. Even so, if the database can be backed up cold, it is simply a matter of skill-set and restoration comfort. RMAN is easy and saves resource and can be paralleled making it much faster than simply cold copying files. However, especially if the database is down, I'd use a disk snap for large multi-terabyte databases. This would be the fastest way to go, but it requires, disk and storage skill-set. I would never simply cold copy the files and have not had to do that in the last 6 years, but my situation is not yours. DBAs are a stubborn bunch. If the catalog argument could be valid if business requirements dictate its usage. It is not a technical requirement.

Here are some links for your DBA.
http://www.nyoug.org/Presentations/2005/20050929rman.pdf http://www.evdbt.com/TD_Rman.pdf Received on Tue Jan 30 2007 - 09:02:02 CST