6 Replies Latest reply: Jan 8, 2013 6:57 AM by 861120 RSS

    RMAN is Very much Slow

    979966
      Hi,

      RMAN Backup(for Oracle R12 EBS DB Instances size 400GB ) process is very much slow with on OEL5.8 64Bit, it takes very long time to complete 15 Hours

      the same RMAN Backup process was quite faster with RHEL4 32Bit OS with same HW Setup and DB.
      and earlier backup time is 8hours.

      I request your help to improve RMAN Backup performance.

      Thanks & Regards,

      Prabhakar.D
        • 1. Re: RMAN is Very much Slow
          saurabh
          post the rman script that you are using and also the output of "show all" in rman console.
          • 2. Re: RMAN is Very much Slow
            979966
            Below are the details of RMAN script which we execute daily:



            awadb_lvl0.rman:

            ----------------------

            run {

            ALLOCATE CHANNEL c1 DEVICE TYPE disk maxpiecesize 20G;

            ALLOCATE CHANNEL c2 DEVICE TYPE disk maxpiecesize 20G;

            ALLOCATE CHANNEL c3 DEVICE TYPE disk maxpiecesize 20G;

            backup incremental level 0

            format '/backup/PROD/RMAN/%d_LVL0_%T_%u_s%s_p%p'

            DATABASE PLUS ARCHIVELOG format '/backup/PROD/RMAN/ARCH/%d_AL_%T_%u_s%s_p%p' skip inaccessible;

            release channel c1;

            release channel c2;

            release channel c3;

            }



            awadb_lvl0_rman.sh:

            --------------------------

            rman catalog awadb_rman/pasword@rmandb target sys/password@awadb cmdfile '/backup/PROD/scripts/awadb_lvl0.rman' msglog '/backup/PROD/scripts/log/rman_lvl0_awadb_Jan02.log'



            RMAN> show all;



            RMAN configuration parameters for database with db_unique_name AWADB are:

            CONFIGURE RETENTION POLICY TO REDUNDANCY 3;

            CONFIGURE BACKUP OPTIMIZATION OFF; # default

            CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default

            CONFIGURE CONTROLFILE AUTOBACKUP ON;

            CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/backup/PROD/RMAN/cf%F';

            CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE SBT_TAPE TO '%F'; # default

            CONFIGURE DEVICE TYPE 'SBT_TAPE' PARALLELISM 2 BACKUP TYPE TO BACKUPSET;

            CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

            CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE SBT_TAPE TO 1; # default

            CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

            CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE SBT_TAPE TO 1; # default

            CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

            CONFIGURE CHANNEL DEVICE TYPE DISK FORMAT '%U';

            CONFIGURE MAXSETSIZE TO UNLIMITED; # default

            CONFIGURE ENCRYPTION FOR DATABASE OFF; # default

            CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default

            CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default

            CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default

            CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/backup/PROD/RMAN/snapcf_awadb.f';

            PS: Rman catalog database is resideing on other server and the vesion is 10.2.0.3.
            • 3. Re: RMAN is Very much Slow
              saurabh
              increase your parallelism depending on your server to 3 or 4

              CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

              this will decrease your time required.
              • 4. Re: RMAN is Very much Slow
                979966
                If you can see backup script, already we are using three channels which will invoke 3 RMAN jobs at time for writing backup pieces to disk.



                ALLOCATE CHANNEL c1 DEVICE TYPE disk maxpiecesize 20G;

                ALLOCATE CHANNEL c2 DEVICE TYPE disk maxpiecesize 20G;

                ALLOCATE CHANNEL c3 DEVICE TYPE disk maxpiecesize 20G;



                Even if we specify parallelism to 3 or 4 number of automatic channels of the specified device type allocated for RMAN jobs which is same and it will not be helpful for us.

                How do you feel, parallelism with above allocation channels c1-c3 device type disk specified.
                • 5. Re: RMAN is Very much Slow
                  SurinderSingh
                  Please share your datafile size.

                  Increase Large Pool size & Shared Pool size

                  Regards
                  Surinder Singh
                  • 6. Re: RMAN is Very much Slow
                    861120
                    Please check the number and size of the buffers used for RMAN job using the views:

                    V$BACKUP_ASYNC_IO and V$BACKUP_SYNC_IO.

                    By default, buffers are allocated from the PGA, unless DISK or TAPE I/O slaves are used, in which case buffers are allocated from the SGA or large pool (if LARGE_POOL_SIZE is set).

                    If the problem not solve, try isolete the problem. If the problem is read (I/O read data from disk) or write (I/O to write data to disk).

                    Create one datafile, is the good way to determine the output disk performance (write operation). and check how long it take, for example:
                    create tablespace tbtest datafile '/oradata/tbtest01.dbf' size 10G;
                    If the command show the same IO rates like the RMAN, then indicate that the problem is the IO performance to this device, not the RMAN.


                    Are you using Asynchronous IO? RMAN supports asynchronous I/O and always recommend using this for performance tuning.

                    Whats file systems are you using? NFS? OCFS? etc... You've already check if there a problem with them?


                    http://flaviosoares.com
                    Flávio Soares

                    Edited by: Flávio Soares on Jan 8, 2013 10:56 AM