Re: Minimizing backup induced downtime

On Jul 13, 8:48 am, Alexander Skwar <alexan..._at_skwar.name> wrote:
> StefanKapitza <skapi..._at_volcanomail.com> wrote:
> > On Jul 13, 8:21 am, Alexander Skwar <alexan..._at_skwar.name> wrote:
> >> sybra..._at_hccnet.nl <sybra..._at_hccnet.nl> wrote:
> >> > On Thu, 12 Jul 2007 23:35:14 +0200, Alexander Skwar
> >> > <use..._at_alexander.skwar.name> wrote:
> >> >>>>From where does RMAN/Oracle
> >> >>>>pull the data about what has been done between 22:46 and 22:59,
> >> >>>>if archive logs aren't available?
>
> >> > The answer to this question is of course: from nowhere.
>
> >> Thanks. So how's that an improvement over doing an EXP?
> [...]
> > The Improvment was (check your Topic) no Downtime.
>
> Well. But please check my OP, <news:2877861.rzr6KgmIHE_at_kn.gn.rtr.message-center.info>,
> where I explained that an RMAN backup would mean either having a larger
> downtime or the odd chance of a user being able to modify something
> "in between". Let me quote the relevant part:
>
> | 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
>
> If I were just to do an EXP, I also would have no downtime, wouldn't I?
> I mean, after all a EXP dump can be done while the database is still in
> production.
>
> The way the application is made, I need to have a downtime, if I want
> to make absolutely sure that the application is in a consistent state.
> I don't need a downtime of Oracle, that's true. But I care much more
> about the downtime of the application then about the downtime of Oracle -
> especially if the Oracle downtime occurs at the same time, the
> application is already down.
>
> But currently I'm not doing just an export. I'm doing cold backups and
> this means a very /short/ downtime. At least in the way it's implemented
> right now.
>
> | 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 advantage here is, that step 3 is very fast and that step 4 is done
> in the background, while steps 5 and 6 are already started or completed.
> As it is right now, I'm doing the exp right before I do step 1. I don't
> care that much about the EXP being in sync with the application. My real
> backup is the one I take from the snapshots. Those snapshots contain the
> database in its shut down state - so it's a cold backup, as far as Oracle
> is concerned. BTW: As the database is running in archivlog mode, I also
> archived redo logs which I store as well on tape.
>
> Alexander Skwar

Backup :
- you take a snapshot a 23:00
- you start an Online Backup with Rman after that

Restore :
- restore your Filesystem Snapshot from 23:00 - Recover your Database until time 23:00

What is your Problem ?

regard

stefan kapitza Received on Fri Jul 13 2007 - 02:23:57 CDT