RE: Fragmentation with restore multiple channels

  • From: "Kenneth Naim" <kennethnaim@xxxxxxxxx>
  • To: <ab80cwb@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 4 Sep 2012 06:38:38 -0400

Rman just allocates the number of datafiles by the number of datafiles so it
you have 120 files and 6 channels, each channel would eventually backup 20
files so no fragmentation is possible with a full backup. With an
incremental or differential backup there could be some validity in theory
but I agree with Tim Gorman that it is just a tuning exercise and most
likely will show another cause but only after conclusive proof would I point
to RMAN as the cause.

Ken

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Alex Cwb
Sent: Monday, September 03, 2012 10:35 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Fragmentation with restore multiple channels

Hi people,

Recently I am facing a problem with fragmentation. A supplier is arguing
that the way we did a restore using RMAN with multiple channels is causing
many fragmentation on the database, and consequently their application on my
company is running slowly.

The restore has been done using 6 channels, and I guess that is not true.
The database is being used for testing purposes only, and during this phase
it's not happening updates.

Anyways, I did some research and I couldnt find a resonable answer. So I am
in doubt if restore in multiple channels really causes fragmentation.
Does someone have any experience on that??

Thank you for sharing.
Alex
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