Re: Duplicate DBIDs

  • From: Steven Patenaude <spatenau@xxxxxxxxx>
  • To: ntilbury@xxxxxxxxxxxx
  • Date: Wed, 26 Jan 2005 12:03:00 -0600

On Wed, 26 Jan 2005 16:31:47 -0000, Nick Tilbury @ Northampton
<ntilbury@xxxxxxxxxxxx> wrote:
> We also had a similar issue. Which version of Oracle are you on ?
> Renaming the database will not change it's DBID, but it can be done by exec=
> uting a procedure
> (the name of which escapes me for now).
> 8i databases having the same DBID did cause us some problems. However since=
>  upgrading to
> 9i, using RMAN duplicate database feature (which does change the DBID) we h=
> ave had no problems.

If they are not using an RMAN repository but instead keeping the info
in controlfiles there shouldn't be any problems.

I have had problems using the duplicate database feature (in 9.2). 
Specifically, if RMAN hits any problems during the duplicate process,
on a restart it'll start from the beginning instead of continuing
where it left off (like it would if you are doing a simple recovery). 
I guess RMAN's logic is:  the restored file has this DBID while the
file in the backup set has that DBID so I need to restore the file
again.

At my old job we were doing this _constantly_ and it caused many
delays.  The media manager was wont to timeout, or mount points would
run out of space (the crappy disk subsystem didn't handle SAME well),
or whatever.  It turned out to be easier to do a normal recovery and
then use nid to change dbname and dbid.  Things were more tricky when
you wanted to create a duplicate on the same server-- had to use the
LOCK_NAME_SPACE init parameter until you got to the nid step and,
well, that works but I don't think it is a process blessed by oracle
support.

The duplicate command is easy and sweet, though, when you are putting
backups to disk or RMAN and the media manager play nicely.

Steven
(This isn't for the TIERS project, is it?)
--
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