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

Frank van Bortel <fvanbortel_at_netscape.net> wrote in message news:<ch6jr7$q4$1_at_news5.tilbu1.nb.home.nl>...
> Joel Garry wrote:
>
> > 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.
> >
>
> Any reason triple is in brackets asif it were optional?
> If not triple, you are breaking a mirror, which you put
> there for a reason...

Technically, it is optional, because if one wanted to accept that one must go to a previous backup and apply all archive logs in the case of a crash during the backup, one could simply run unmirrored (but with archived logs mirrored) while breaking the second mirror. It would be an unusual way to go. Might be necessary temporarily during maintenance [ie, some time before new disks arrive and are installed] or if several disks failed at once with a triple scheme.

> BTW, ever waited for a mirror to be synchronized, in a case where
> a reasonable (30 GB) sized db was located on the other member?
> Did bring the backup schedule in jeopardy (AIX 4.3 / 8 CPU S70).
>
> As Joel stated, but did not emphasize enough, it depends
> how fast your mirroring works.
> And I'd like to add: and how much performance impact it imposes
> on your application!

I started to emphasize it more, but then I'm not up on the most modern SANS and didn't want to judge that which I don't know. As always, testing may trump sales shpiels.

jg

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