4 Replies Latest reply: Aug 27, 2013 4:46 AM by saurabh RSS

    channels in rman

    941949

      dear all,

                    i want to know how the channels in rman backup works? below is the rman backup log and my question is when channel c1:finished piece 1 then why channel c2:is starting the same piece 1.your help appreciated thanks in advance.

       

      Starting backup at 26-AUG-13

      channel c1: starting incremental level 0 datafile backup set

      channel c1: specifying datafile(s) in backup set

      input datafile file number=00379 name=/mnt/oradb/undo01.dbf

      input datafile file number=00040 name=/mnt/oradb/a_media06.dbf

      input datafile file number=00053 name=/mnt/oradb/a_media09.dbf

      input datafile file number=00031 name=/mnt/oradb/a_txn_data05.dbf

      input datafile file number=00035 name=/mnt/oradb/xxcust_data_02.dbf

      .

      .

      .

      .

      .

      channel c1: starting piece 1 at 26-AUG-13

      channel c2: starting incremental level 0 datafile backup set

      channel c2: specifying datafile(s) in backup set

      input datafile file number=00024 name=/mnt/oradb/undo03.dbf

      input datafile file number=00041 name=/mnt/oradb/a_media07.dbf

      input datafile file number=00048 name=/mnt/oradb/a_media08.dbf

      input datafile file number=00018 name=/mnt/oradb/discoverer

      .

      .

      .

       

       

      channel c2: starting piece 1 at 26-AUG-13

      channel c1: finished piece 1 at 26-AUG-13

      piece handle=/mnt/oradb/rmanbackup/df_13_1_824489900.rmn tag=DAILY_BACKUP comment=NONE

      channel c1: starting piece 2 at 26-AUG-13

      channel c2: finished piece 1 at 26-AUG-13

      piece handle=/mnt/oradb/rmanbackup/df_14_1_824489901.rmn tag=DAILY_BACKUP comment=NONE

      channel c2: starting piece 2 at 26-AUG-13

      channel c1: finished piece 2 at 26-AUG-13

      piece handle=/mnt/oradb/rmanbackup/df_13_2_824489900.rmn tag=DAILY_BACKUP comment=NONE

      channel c1: starting piece 3 at 26-AUG-13

      channel c2: finished piece 2 at 26-AUG-13

      piece handle=/mnt/oradb/rmanbackup/df_14_2_824489901.rmn tag=DAILY_BACKUP comment=NONE

      channel c2: starting piece 3 at 26-AUG-13

      channel c1: finished piece 3 at 26-AUG-13

      piece handle=/mnt/oradb/rmanbackup/df_13_3_824489900.rmn tag=DAILY_BACKUP comment=NONE

      .

      .

      .

      .

      MY QUESTION IS WHEN CHANNEL C1 FINISHES BACKUP PIECE 1 (&2,&3) THEN WHY CHANNEL C2 STARTING THE SAME PIECE 1(&2,&3).YOUR HELP APPRECIATED .THANKS.

        • 1. Re: channels in rman
          DK2010

          Hi,

           

          In very simple term you can say channel  represent the parallelism  for Backup set.

          >>MY QUESTION IS WHEN CHANNEL C1 FINISHES BACKUP PIECE 1 (&2,&3) THEN WHY CHANNEL C2 STARTING THE SAME PIECE 1(&2,&3).YOUR HELP APPRECIATED

          No, Its not like that, backup start in parallel and writing two backup set(backup files) simultaneously , may be in your RMAN backup command there is fixed size specify for backup set , so once one backup set complete, it go for next backup set and so ..on..


          You can also check this link :ALLOCATE CHANNEL


          HTH

          • 2. Re: channels in rman
            Pavan Kumar

            Hi,

             

            You have posted partial output of rman and explaining things across.

            1. Try to check what is the parallelism setted for rman configuration

            2. Next No channel will be taking same backup (taken by different channel)

            3. After looking into your issue/log the "piece handle" ... the are fine

             

            channel c2: starting piece 1 at 26-AUG-13

            channel c1: finished piece 1 at 26-AUG-13

            piece handle=/mnt/oradb/rmanbackup/df_13_1_824489900.rmn tag=DAILY_BACKUP comment=NONE

            channel c1: starting piece 2 at 26-AUG-13

            channel c2: finished piece 1 at 26-AUG-13

            piece handle=/mnt/oradb/rmanbackup/df_14_1_824489901.rmn tag=DAILY_BACKUP comment=NONE

            channel c2: starting piece 2 at 26-AUG-13

            channel c1: finished piece 2 at 26-AUG-13

            piece handle=/mnt/oradb/rmanbackup/df_13_2_824489900.rmn tag=DAILY_BACKUP comment=NONE

            channel c1: starting piece 3 at 26-AUG-13

            channel c2: finished piece 2 at 26-AUG-13

            piece handle=/mnt/oradb/rmanbackup/df_14_2_824489901.rmn tag=DAILY_BACKUP comment=NONE

            channel c2: starting piece 3 at 26-AUG-13

            channel c1: finished piece 3 at 26-AUG-13

            piece handle=/mnt/oradb/rmanbackup/df_13_3_824489900.rmn tag=DAILY_BACKUP comment=NONE

            - Pavan Kumar N

             

            I have not correctly observed the peice name, the rman log looks fine.

            • 3. Re: channels in rman
              Hemant K Chitale

              If you look at the piece name  (as "piece handle") you will see that each piece is a different file.

               

               

              Hemant K Chitale


              • 4. Re: channels in rman
                saurabh

                It not what your are thinking. Two channels are not writing on one file at same time. What you see is that channel 1 has finished writting on one of its file where channel 2 has starting to write on the new file. If you check the log properly after piece handle=/mnt/oradb/rmanbackup/df_14_2_824489901.rmn tag=DAILY_BACKUP comment=NONE there will be a line which tells which channel has completed and its elapsed time. Each channel is writing on different file.

                 

                Can you post the rman script you are using as well as your RMAN configuration setting for the same.