Re: "Mirroring" of DBF files

Keith Kris wrote:

>Hi all,
>
>I'm a UNIX admin, and only have minor oracle experience, so chances
>are this is a stupid question (there are no stupid questions, only
>stupid people.) We have a production database which is growing a
>little large. We're in the process of adding more disk to allow
>growth. We'd like to migrate the existing system away from the 12GB
>volumes it currently uses, and toward 72GB volumes. We'd like to have
>only one size of volume used on the system, so we'd need to move our
>data from the old ones to the new larger filesystems. Talking to our
>DBA, he says the only method to accomplish this is to shut down the
>database, move the files, modify init.ora and bring the instance back
>up. The problem with this is it would create too much down time
>(we're moving more than a quarter terabyte.) Is there any method
>within oracle to have the database either use two identical copies of
>a DBF file simultaneously (essentially mirror them) or to have oracle
>itself relocate a DBF file to prevent downtime? I'm open to ideas
>here, so creative thinking is welcome.
>
>Thanks
>Keith
>
>

Send your DBA to a decent Oracle class. This can all be done with zero down-time assuming
you have 9i and probably even with 8.1.7 (you provided no version information and I haven't
worked with 8i in several years) and I can't imagine any data move that would cause anyone to
change the init.ora. The init.ora knows nothing about the location of datafiles or the names of
tablespaces.

All you need to do is add the new disk to the system and create new tablespaces on them.
Then you can use any number of techniques to move the data while on-line. One that I would
seriously consider is the DBMS_REDEFINITION built-in package.

You might want to look into hiring a consultant for one week to set this up and provide
some training too. Once you know how to do this you can continue the process without
the consultant.

-- 
Daniel Morgan
http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp
http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp
damorgan_at_x.washington.edu
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