1) Increasing the number of channels causes additional streams of data.
Depending on how your network is configured, this can increase the
overall speed of the backup.
2) We currently back up single databases using 3 channels for larger
ones and 2 for smaller ones.
3) No, it will stream to the same tape but your overall throughput will
increase. For example, we tried using just one channel and got about
19MB/s throughput. When we increased to 3, we went up to about 35MB/s
to 40MB/s depending on overall network traffic, load on the box, and
etc.
4) Yes, that is exactly what it does.
R. Scott McKnight
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU]
On Behalf Of Bhaskar Mylavarapu
Sent: Tuesday, August 22, 2006 6:07 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Questions on Oracle RMAN channels with NetWorker?
Hi,
We're very confused here about this concept of "channels", as used in
Oracle RMAN scripts, and how this effects NetWorker, and we're hoping
someone can enlighten us. We have NetWorker 7.2.2 on a Solaris 9 server
with the NMO license installed. We're using Oracle 10g on the client
machine which is also running NetWorker 7.2.2 client and has the NMO 4.2
software installed. We're planning to test backing up a test database.
We've read through the Legato Admin. guide for NMO multiplatform
version, but we're unclear exactly how a channel effects the backups.
In other words, is a channel purely an Oracle thing, or does it also
influence how NetWorker will in turn behave? Is it similar to a save
stream or a session? I'm unclear if it makes sense to associate an
Oracle backup with a normal save set stream but just asking if there's
any correlation in the terminology. Let's say I set my RMAN script to
use two channels rather than one. Does this translate somehow to sending
2 streams to the NetWorker tape device on the other end? Or does it
still send a single save stream as far as NetWorker is concerned, but
the dual channels remains purely an Oracle thing?
1. Why would increasing the number of channels be beneficial and what
are the justifications for doing this?
2. If we're only backing up one database, does more than one channel
make sense?
3. If, for example, you set the RMAN script to use two channels, will
this require two tapes on the NetWorker end?
4. Does using multi-channels somehow split the Oracle backup into more
than one stream?
Would greatly appreciate any clarification on this.
Bhaskar
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