Re: UNIX root backup/SAN disk image vs. Oracle Hot Backups

idogan_tech_at_yahoo.com (Ibrahim DOGAN) wrote in message news:<6bf58828.0409010559.5ccd70bb_at_posting.google.com>...
> Can UNIX root backup or SAN disk image backup be reliable as Oracle
> database backup?
>
> I don't know internals about root backup or disk images but it sounds
> like you may end up with inconsistent control file/datafiles when you
> load them back ?
>
> is there anybody out there who knows how root backup/disk image works
> and can tell whether they can replace Oracle hot backups?
>
> Thanks a bunch
> i.d.

As Sybrand sort-of intimated, they must work together. So, it depends how fast your mirroring works. The general idea is to [triple-]mirror, put all tablespaces into backup mode, break [extra] mirror, take out of backup mode, and copy the image at your leisure.

Backup mode causes much more writing to logs (look up "fractured blocks" in the Oracle docs), so that's why RMAN is better versus copying one tablespace at a time over a period of time, it has a much lower impact on log writing. Image copies moot that, if they are fast enough. Some configurations take a long time to resilver the mirror, so, it depends, on transaction load, hardware, requirements, data size, etc.

Of course, RMAN has a lot of other benefits that might outweigh a naive site-specific mirroring strategy.

jg

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