RE: RMAN Peformance and how to optimise
- From: John Kanagaraj <john.kanagaraj@xxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 17 Feb 2004 12:12:36 -0800
John,
If the number of tape and RMAN channels were equal to the number of drives
available, then you will have optimized tape streaming during backup (saves
backup time) as well as restore time. Increasing the number of channels will
not solve, but only degrade your backup (and restore) timings. Why don't you
look at disk pooling or staging (I know that is available in ADSM now
Tivoli, maybe it is available on Legato 7?) We had a similar issue (with
just normal files) 4 - 5 years back and I am speaking with that in mind...
(so YMMV)!
John Kanagaraj <><
DB Soft Inc
Phone: 408-970-7002 (W)
Listen to great, commercial-free christian music 24x7x365 at
http://www.klove.com
** The opinions and facts contained in this message are entirely mine and do
not reflect those of my employer or customers **
>-----Original Message-----
>From: oracle-l-bounce@xxxxxxxxxxxxx
>[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
>John.Hallas@xxxxxxxxxxxxxxxxx
>Sent: Tuesday, February 17, 2004 11:43 AM
>To: oracle-l@xxxxxxxxxxxxx
>Subject: RMAN Peformance and how to optimise
>
>
>
>We are seeing poor performance when recovering a full database (65 =
>datafiles) , during backup revovery (testing I hasten to add
>so not job =
>or life threatening)
>
>Oracle 9202 Legato Networker 7 (I think) filesperset 1 2 tape
>drives 8 =
>channels
>
>What appears to be the problem is that the order that the backup was =
>taken (full) does not co-incide with the order that the files
>are being =
>recovered (using RMAN logs to tell the order)
>
>From NW we are seeing 1 channel reading from tape and laying down the =
>file to disk and 7 channels idle.
>We suspect that they are waiting on the same tape but for a different =
>part of the tape.
>Ideally what we want is a means of RMAN recovering the
>datafiles in the =
>order they are on the tape.
>
>I have seen a note on Metalink suggesting that either 1 or 2
>channels is =
>best per available tape drive.
>
>We have to strike a balance betweeen the backup time and the recovery =
>time with neither taking extremes.
>
>
>Has anybody done any work in this area that could offer some useful =
>insights
>
>Thanks
>
>
>John
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