A note about RMAN

How Oracle Works  - A note about RMAN

Let me first say YOU DON'T HAVE TO USE RMAN TO TAKE HOT BACKUPS!

I'm amazed at how many people still take cold backups because they don't understand RMAN and think it is the only proper way to take backups.

In my opinion, RMAN wasn't even a very good tool when it first came out. It has now matured and is something that should be CONSIDERED by everyone.

Don't forget the most important question...'WHY?"

Well, RMAN is better than OS backups, right? Well, yes or no. If you are not using hot backups at all, then RMAN is useless anyway, right? So first start taking hot backups, then learn how to migrate to RMAN.


INCREMENTAL vs. FULL backups in RMAN

Oracle has made it easy for people to not understand these backups in RMAN.

If you're not using 10g and "true incrementals", just use full. Older versions of RMAN were not much faster because it had to do just as much reading as a full backup (read the whole datafile, backup anything that's changed). They were ONLY designed to save disk/tape speed and/or bandwidth to disk/tape. They certainly didn't speed up recovery.

In 10g, they've FINALLY introduced a "change tracking file" and many other enhancements like incrementally Updated Backups.

So, RMAN started out as a ham fisted tool that caused problems for a lot of people (but did help many who dedicated themselves to it), but has now become much more of an asset to the DBA.

I use RMAN and I am glad I do. But I also use 10g. I still have problems recommending it to people on older versions.

Read through the product docs and you can see what it offers (you'll notice RMAN doesn't have to put your tablespaces in backup mode). It also seems to be a lot easier to use nowadays, but maybe I've just gotten used to it.

Like anything in Oracle, there are lot's of powerful tools and features for you to exploit if you know WHY to. Don't be one of those poor saps that tries to use every feature or tool just hoping that it's the proper way of doing it.

Analyze YOUR needs and use the pieces you'll need. You'll be more successful and get a lot more sleep.