Re: RMAN or Hot Backup
Date: Thu, 26 Mar 2009 19:32:24 -0500
Mladen Gogala wrote:
> On Thu, 26 Mar 2009 11:07:14 -0700, jgar the jorrible wrote:
>> The only reason to use hot backups is if you have an expensive hardware >> solution such as triple mirroring, that can split off a mirror more >> rapidly than other ways of moving data around.
> Not quite. There are open source backup products that do not work with
> RMAN and do work with hot backup mode. Examples of such software are
> Bacula and Amanda, both excellent pieces of software which can control
> robots, catalog backups and do most of the stuff that very expensive
> commercial backup pieces can do. If your company wants to cut costs and
> use open source, Bacula can be a real money saver. I know that RMAN is
> the mainstream, but hot backup can be cheaper. Much cheaper. On the other
> hand, backup system is the last system that I would consider for saving
> Also, NetApp has snapshots which are not supported by RMAN. They also have
> a backup, based on hot backup mode, which can do quick snapshot backups
> for you. Hot backups are very useful.
Be VERY careful how you use the NetApp "snapshot" - make sure your database is "quiet" when doing this or you may not get the results you expect when you try to "restore". Oracle, SUN and NetApp having been working an issue for my previous employer for a month or two now for an EXTREMELY busy and VERY large db. They add more data in a day than the average db in America adds in a year (or more) - sorry no numbers - at least not until I get all my severance pay :) )
EMC has the BCV (Business Continuity Volume) where they use HotBackup Mode to "clone" a database by breaking a mirror and importing it into another instance. Again, On a very busy system, once or twice/week they would end up with corrupt undo-segments causing ORA-600 errors pointing to those corrupt segments. Basically, if you continually do a "controlled" crash like this, you are lucky more often than not if it works...
Been there, Done That and didn't like it...
Both methods become very difficult and almost unusable when you try to use Transparent Data Encryption or other Advance Security Options. (requirement for both SOX and PCI (credit-card processing))
For most medium-sized large databases (rarely see the sizes as my last employer had..) RMAN to DISK would be my first choice - going directly to tape is suicide. In my career, I have seen FAR too may instances where for example, tape 14 of 15 craters and you are hosed.
And with an ONLINE FULL backup and the ability to do block-level restores - why would you do anything else? (BTW- this is another feature that came from the Oracle/Rdb (formerly DEC/Rdb) product. Received on Thu Mar 26 2009 - 19:32:24 CDT