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RE: Methods to clone large production database

From: Pal, Raj <>
Date: Wed, 28 Mar 2007 11:12:20 -0600
Message-ID: <>

9 hours seems long for 750Gb to disk. I'm seeing 10hrs:40min for a 9.8Tb (segment size alone) database. Mind you, there are 32 cpus and 196 Gb mem, but the backup is writing to SAN attached Clariion-ATA disk (fairly slow... and inexpensive). We're also using 33 channels with not too much of a performance hit. So for the 750Gb 0hr backup... are you using a catalog database? If so, how?

Since the original post was for an alternative to RMAN duplicate for the creation of the other database... try "RMAN copy" of datafiles. Recovery will be necessary, but "hot-backup-mode" will not be necessary. When duplicating the database mentioned above, we mount disk to the host, RMAN copy the datafiles over, and then remount the disk to the host we want to duplicate the database on. This was only done due to the size of the database and the fact that we have had past issues with "hot-backup-mode" for large databases. Works well, so is appropriate for same host replication if you can't get the duplicate to work.

-----Original Message-----
[] On Behalf Of Don Seiler Sent: Wednesday, March 28, 2007 9:31 AM
Cc: Allen, Brandon; Subject: Re: Methods to clone large production database

Prior to RMAN, we would go tablespace-by-tablespace, putting them into BACKUP mode, then doing a gzip -c to copy and compress the datafiles on the fly. This was done to disk, and then that disk was copied to tape the next morning. The whole backup process took less than 3 hours on our ~750gb database, which we did in full every night. We could do restores for development by basically emulating a disaster recovery from one of the backups.

Now we're on RMAN on 10gR2, and a level 0 backup takes over 9 hours. I'm certain that I have some tuning to do, but we're living with doing one level 0 on Saturday night when we have an extended window without many users. The rest of the week we do a level 1 with block change tracking enabled, and it takes 20-40 minutes, which is very nice, and makes the 9 hour level 0 much more easier to swallow for now. As before, we backup to disk. I also then use rsync to push copies of the backup disk slab to our development server as well as a third box for safe-keeping.

For cloning, I run an RMAN "duplicate database" command. We have a retention policy of 7 days, so the developers can request a restore to any point in the last 7 days for their development instances.


On 3/27/07, rjamya <> wrote:
> we use raw files. take hot backup and create a create_controlfile.
After the
> hot backup, we run multiple dd's over private network from one server
> another. once those are copied (and renamed) over, we manipulate
> file script and create the control file, and preform recovery to the
> Along with data files, we also copy over archive logs to help in
> rjamya
> On 3/27/07, Allen, Brandon <> wrote:
> >
> >
> > What exactly is the "raw copy method"? Do you just mean that you
put the
> database/tablespaces in backup mode and copy with the OS utilities?
Or is
> it something to do with raw storage, in which case I didn't think you
> use the OS copy utilities, but I'm not really sure since I've never
> with raw storage.
> >
> > Thanks,
> > Branddon

Don Seiler

Received on Wed Mar 28 2007 - 12:12:20 CDT

Original text of this message