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Thread: RMAN took 12hrs to restore

  1. #11
    Join Date
    Sep 2001
    Location
    Ohio
    Posts
    334
    Originally posted by jlakhani
    How many more channels would you recommend? I read somewhere on metalink that for Omniback it requires 4 channels and doesnt use more then 4 channels..
    I don't know anything about Omniback, but if you only have 2 devices, I wouldn't think you would want anymore than 2 channels.

    You can always test it out. Configure 4 channels, run a backup, and see how many channels are used. If you look at the output of your backup, it will tell you which channels are used. It may "allocate" 4 channels, but see how many are actually used at one time. Then run it with 2 and then 1 channel. Look at your times and your throughput.

    Like slimdave and Jeff always say... you need to benchmark!

    Good Luck!

  2. #12
    Join Date
    Jul 2002
    Location
    Northampton, England
    Posts
    612
    Like Jodie said, you may well have something else happening with your tape device... I did an adhoc backup a while back before a major DB change and left it to play golf for a couple of hours (ahem... hope my boss doesn't read this, I was claiming overtime...). When I came back, it had only done about 1% of the backup because the cleaning tape was trying to eject one of my tapes as part of a scheduled maintenence routine. Once I stopped the maintenence plan, the backup flew.

  3. #13
    Join Date
    Aug 2000
    Location
    Chicago IL
    Posts
    586
    I am going to use 4 channels to do a backup and see how fast that runs.. Also, if I wanted to restore RMAN to a different location/Server then do you have a suggestion on how I can do that?

    thanks
    Jigar
    "High Salaries = Happiness = Project Success."

  4. #14
    Join Date
    Feb 2003
    Location
    Leeds, UK
    Posts
    367

  5. #15
    Join Date
    Aug 2000
    Location
    Chicago IL
    Posts
    586
    You see this is our current rman scrpt: We are doing an incrimental 0 backup
    Question 1: If I use backup database or backup full command rather then backup incremental level filesperset 1 will my backup/restore run faster?

    Question 2: Currently my fileperset is 1 for 116 datafiles. If i change that to 52 which is half of 116 then will all the channels be utilized? What if I dont specify a fileperset..will rman figure out he fileperset? Omniback limits fileperset to 1..

    allocate channel 'dev_0' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_1' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_2' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_3' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_4' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_5' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_6' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_7' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_8' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    allocate channel 'dev_9' type 'sbt_tape'
    parms 'ENV=(OB2BARTYPE=Oracle8,OB2APPNAME=trxp,OB2BARLIST=TRXP_RMAN_Online)';
    backup incremental level filesperset 1
    format 'test_rman.dbf'
    database
    include current controlfile
    ;
    }
    "High Salaries = Happiness = Project Success."

  6. #16
    Join Date
    Sep 2001
    Location
    Ohio
    Posts
    334
    Originally posted by jlakhani
    You see this is our current rman scrpt: We are doing an incrimental 0 backup
    Question 1: If I use backup database or backup full command rather then backup incremental level filesperset 1 will my backup/restore run faster?

    Question 2: Currently my fileperset is 1 for 116 datafiles. If i change that to 52 which is half of 116 then will all the channels be utilized? What if I dont specify a fileperset..will rman figure out he fileperset? Omniback limits fileperset to 1..

    Question 1 - Backup database and backup incremental 0 are the same except one can be used in an incremental restore, the other can't. I'll let you guess which one is which!

    Question 2 - I feel like I'm talking to a brick wall here. You can only use as many channels as you have tape devices. Like I said, I know nothing about Omniback, but that's the way it works for all the other media managers I know about.

    I did search google a bit for your problem (You may want to try that too!) A quick look and I found that Omniback DOES appear to limit filesperset to 1. (A MAJOR downfall in my opinion) So if that's the case, and you have 116 datafiles, each backup will consist of 116 pieces. If you open 1 channel, it will back up 1 at a time. If you use 2 channels, you can finish in roughly half the time since you are backing up 2 files at the same time - assuming your bandwidth can handle it. Using more channels is a WASTE since you only have 2 devices!!!!

    Another thing I found in my google search is that omniback implements a wait between each file when doing a restore. (Another downfall in my opinion). The poster (on the IOUG Forum) said that after tweaking some parameters, he got the wait down to 1-1.5 minutes. That means by default, this must be higher. So, with your 116 files, your looking at ~3 hours of wait time on a restore - at least. OUCH!

    All of my opinions are based on my experience which has nothing to do with Omniback. I highly suggest you read (or re-read) the RMAN Users guide and find some good documentation for Omniback! You should also start paying close attention to the output of your backups and restores so you can see exactly what is happening. Watch the output as the backups, etc are happening. You might be surprised at what you learn... like what channels are restoring what pieces and in what order.

    Good Luck
    Jodie

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