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Question on RMAN DB Restore Channels

Created: 12 Nov 2012 • Updated: 24 Dec 2012 | 7 comments
This issue has been solved. See solution.
One of my DBA has triggered this DB Restore which was backed up via RMAN. Even though he have given 3 Channels, it has triggered 12 restore jobs in activity monitor. Not sure how this happened. Any Idea?
run {
allocate channel ch1 device type 'sbt';
allocate channel ch2 device type 'sbt';
allocate channel ch3 device type 'sbt';
send 'NB_ORA_POLICY=DB_rman_full,NB_ORA_SERV=master-bk';
restore database;
release channel ch1;
release channel ch2;
release channel ch3;
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Nicolai's picture

Did he fire off the restore rcv script multiple times?. Check the times in the activity monitor.

Assumption is the mother of all mess ups.

If this post answered your'e qustion -  Please mark as a soloution.

Karthikeyan Sundaram's picture

Nope. he mentioned that he have triggered it with 3 Channels

Thanks, Karthikeyan Sundaram.

Will Restore's picture

Check the details of each item. I'm guessing there are child tasks of the three parent jobs.

Will Restore -- where there is a Will there is a way

Yasuhisa Ishikawa's picture

triggered 12 restore jobs in activity monitor

Does this mean 12 jobs goes active simultaneously or 12 jobs were generated onsecutively?

If you mean later, it is normal. From Oracle perspective, 12 backup pieces were read for restore.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Karthikeyan Sundaram's picture

Yes, I see it was not triggered simultaneously, instead it was one by one..If you say normal, how does the 12 pieces calculated for 3 channels..So does that mean 4 streams will be created for restore read per channel?

I had time to look at documents which all say me that, it will generate jobs as per the channels given.

BTW, Appreciate your help. I have seen many of  the discussions on oracle issues during this issue research. You are really helping many of us.

Thanks, Karthikeyan Sundaram.

Yasuhisa Ishikawa's picture

"it will generate jobs as per the channels given", this is not correct. When oracle request backup pieces to NetBackup througt sbt interface, one job will be generated for each backup piece.
From Oracle perspective, 3 channel means you can read and write up to 3 backup pieces simultaneously.

In this case, your database backup consist of 12 backup pieces. On each channel, Oracle read backup pieces one by one - one piece is eneded, next piece begins.

You can understand this more by comparing RMAN log and reuested files on each restore jobs. Backup piece handle is passed as file name from Oracle to NetBackup.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Karthikeyan Sundaram's picture

thanks Yasuhisa.. let me have a check on it further..appreciate your time in responding.

Thanks, Karthikeyan Sundaram.