Oracle-L: RE: RMAN backup with MULTIPLE CHANNELS ......

From: <Jared.Still_at_radisys.com>
Date: Thu, 20 Feb 2003 13:02:18 -0800
Message-ID: <F001.00553776.20030220130218@fatcity.com>

One possibility is that the backup job is already maxing out the network connection between the client system and the Veritas NetBackup master server and/or media server.

If you have a 10megabit network and LTO drives, the network will never be able to keep the tapes streaming. Adding 3 channels won't help if your network can't keep up.

I'm speculating here, as you don't really supply enough info about your environment.

Jared

Janardhana Babu Donga <jbdonga_at_ucdavis.edu> Sent by: root_at_fatcity.com
02/20/2003 10:47 AM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
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        Subject:        RE: RMAN backup with MULTIPLE CHANNELS ......

Dennis,

Thanks for your reply. Iam taking tape backup with 3 channels as we have multiple tape drives. I don't know where the bottleneck is. In the RMAN output I see it is using all the three channels simultaneously with 10 datafiles per channel. But Iam not getting the throuput. It is taking the same amount of time as it used to take for single channel. I don't know where to look, and don't know how to fix the problem and take advantage of multiple channels.

Babu

-----Original Message-----
Sent: Thursday, February 20, 2003 9:39 AM To: Multiple recipients of list ORACLE-L

Babu - We allocated multiple channels on an RMAN disk backup and the backup
time was reduced. I would suggest you try to figure out where your bottleneck is. Are you writing to multiple tapes? Actually, RMAN has several
features to keep the tape streaming, you may want to look at these. If your
tape isn't streaming, you might get more throughput from a single tape drive
than you are now.

Dennis Williams
DBA, 40%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Thursday, February 20, 2003 10:44 AM To: Multiple recipients of list ORACLE-L

Dear List,

I have changed my RMAN backup script to use multiple channels(3) as we have
plenty of tape drives. It is taking the same amount of time as it used to with single channel. The DB size is 120gig. The output indicates it is using
three channels while backing up. Anyone has any idea why the multiple channels not reduced the backup time. Iam using Veritas Netbackup. Thanks in advance for any help.

Babu
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Author: Janardhana Babu Donga INET: jbdonga_at_ucdavis.edu

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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM

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Author:
INET: Jared.Still_at_radisys.com

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