Re: Backup of large databases

On Oct 28, 1:06 am, zigzag..._at_yahoo.com wrote:
> On Oct 27, 9:20 am, zigzag..._at_yahoo.com wrote:
>
>
>
> > On Oct 26, 8:19 pm, hpuxrac <johnbhur..._at_sbcglobal.net> wrote:
>
> > > On Oct 26, 4:53 pm, zigzag..._at_yahoo.com wrote:
>
> > > > I am still on Oracle 8.1.6.1 on HP UNIX 11, I am using RMAN for
> > > > backups. We are going to setup a large data warehouse which is
> > > > expected to grow to 500GB. My main concerns is backup times taken by
> > > > database backups. Currently, for 20GB database size, full backups take
> > > > 12 hours to complete, I am using RMAN with default parameters and only
> > > > one channel is being used:
> > > > Allocate channel ch1 type 'SBT_TAPE';
>
> > > > I think reason backups take so long is Network band width. Our servers
> > > > reside in a local data center but backups are done over WAN in central
> > > > data center where all Netbackup tape servers and tape drives reside.
> > > > We cannot move our databases to central data center.
>
> > > > Only parameters which I know to experiment are usng multiple channels
> > > > and tuning some init.ora parameters documented in RMAN manual.
>
> > > > I will appreciate any other ideas.
>
> > > RMAN at 8.1.6.x wasn't exactly really stable exactly.
>
> > > I backup a much larger database to tape in less than an hour. Can you
> > > get a bigger pipe over the network for the backup traffic or move to a
> > > local tape unit?
>
> > > You might want to look at disk based backups?- Hide quoted text -
>
> > > - Show quoted text -
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> > If I backup to disk using RMAN and then backup the backupsets (on
> > disk) to tape, why do you think backup times will decrease. Also,
> > since my database size is 500GB, Let us say I want to keep a month's
> > backups on disk everyweek I do full backup and on weekdsays do
> > incremental backup, won't I need 2000GB to 25000GB anount of disk
> > sapce.- Hide quoted text -

RMAN backups are smaller than database size.

> > - Show quoted text -
>
> What I meant was backing up from disk to tape can also take lot of
> time ober network unless I backup to a local tape drive.

Let's accept that you found your bottleneck - the network. If so, you should either avoid it completely or get across something smaller it can cope with. I see a couple of options: - backup locally on tape and ship them off site - backup locally on disk, compress backups and transfer much smaller files over slow network.

In any case, start talking to the management, like yesterday :) You don't want to end up as a scapegoat, do you?

Igor Received on Mon Oct 29 2007 - 18:31:04 CDT