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Re: VLDB Backup Solutions

From: Mark Rosenbaum <mjr_at_netcom.com>
Date: 1997/02/11
Message-ID: <mjrE5GorI.Hy1@netcom.com>#1/1

In article <5dq5sq$dv5_at_camel1.mindspring.com>, Doug Anderson <dathedba_at_mindspring.com> wrote:
>One very slick way of performing a backup of a large database involves
>the use of a particular file system structure on Digital Unix. Using
>the AdvFS file system, you can do the following.
> 1. Shutdown Oracle for just a few minutes.
> 2. Create a 'clone' of the file sets involved.
> 3. Startup the database.
> 4. Perform the backup of the 'clone'.
> 5. Remove the 'clone' when the backup is finished.
>
>The main idea here is to let the file system handle what Oracle tries
>to do with the 'hot backup' scheme. Except here the backup is really
>a 'cold backup'. The database only needs to be down for less than
>10 minutes while the clone is created.
>
>What the cloning does is creates a directory structure with all the
>meta-data about the datafiles and such. It also causes the file
>system to copy any BLOCKS (not files) which change. The original
>block is copied to the clone-area anytime that a changed block is
>written to the normal disk files.
>
>Therefore, since most of a large database is static during a backup,
>the clone points to the normal blocks of the datafiles. But when it
>recognizes that a block has changed it points to the copy of the
>original block.
>
>Way cool!
>

Doug,

That is way cool, but I have a few questions.

What does this do to performance?
Can the clone be on differet disk than the original? Does it work with raw files?

tia

mjr Received on Tue Feb 11 1997 - 00:00:00 CST

Original text of this message

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