Re: Minimizing backup induced downtime

On Jul 12, 7:33 am, Alexander Skwar <alexan..._at_skwar.name> wrote:
> Hello.
>
> As you might have noticed :), I'm trying to learn RMAN and am thinking
> about how to use it right for our backups. As it seems to me right now,
> the use of RMAN will make the downtime because of backup *LARGER* than
> it is right now.
>
> Let me explain how I currently do a backup.
>
> 1) Shut down application, which uses Oracle as a backend
> 2) Shut down Oracle
> 3) Create filesystem snapshots with ZFS on Solaris 10
> 4) Start backup to tape of filesystem snapshots. When done, remove snapshots
> 5) Startup Oracle
> 6) Startup application
>
> The step 4 is run in the background. Because of this, the actual
> downtime is very small (a matter of seconds. At most, it's 1 minute).
> I'm currently shutting down everything, so that the files on backup are
> in a consistent state.
>
> I'm now thinking about how to fit RMAN into this picture. I think it
> might look something like this:
>
> 1) Shut down application, which uses Oracle as a backend
> 2) Have RMAN create backup of database
> 3) Create filesystem snapshots with ZFS on Solaris 10
> 4) Start backup to tape of filesystem snapshots. When done, remove snapshots
> 5) Startup application
>
> Here, step 3 is in background. But I cannot start step 3, before step 2
> is actually finished. Because of this, the downtime of the application
> will be larger, won't it? Granted, I don't have to shutdown the
> application, but then I don't know that I'm in a consistent state. Suppose
> that I do not shutdown the app while RMAN is running. Then a user comes,
> adds/deletes/modifies something. This modification is then, of course, not
> part of the backup I'm doing at this run. Even worse - the FS snapshot
> doesn't "harmonize" with what's in the DB (the application creates/deletes
> files in a so called "vault", which is some directory on the server).
>
> Because of all of this, I'd like to shutdown the application while RMAN
> is running.
>
> In such a scenario/setup, wouldn't RMAN make the downtime larger? Or am
> I overlooking something completely (which might of course be true)? Hm,
> right now, I'm pretty much thinking, that a shell script based backup
> (as I'm currently doing) is a better approach, don't you think?
>
> Regards,
>
> Alexander Skwar

Just take an export...LOL! Given the other concurrent thread, I figured that would get some posters blood boiling :)

RMAN is the way to go. You don't need to have anything down, you can take incremental backups that can be much faster than anything else you have noted, and it is probably (at some point) all Oracle will support going forward.

It's an incredibly powerful technology.

Regards,

Steve Received on Thu Jul 12 2007 - 08:41:14 CDT