3 Replies Latest reply on Feb 18, 2010 6:12 PM by khs

    hot backup using RMAN

      We currently take Oracle hot backups of our 10g databases using Netapp snapshot and EMC BCV. Since RMAN is free, we would like to solely leverage
      RMAN to backup our databases. I have read on RMAN but I could not figure out how to perform hot backups without having to spend time and
      system resources to actually physically copy the Oracle datafiles. I understand I can run multiple channels in RMAN and that would speed up the datafile copy but to copy a 3TB database during a hot backup would still take a lot of time. Currently our nightly hot backup using Netapp completes in seconds since it just takes a snapshot of the volumes without having to do a physical copy.

      I wonder how others are handling hot backups using RMAN. Also how would you take a backup of your database using RMAN prior to a database upgrade? Do you physically copy all the datafiles? For Netapp, we shutdown the database and takes a snapshot. It takes a few seconds to backup a 3TB database prior to applying any patches or database upgrades.

      Thanks for any feedback.
        • 1. Re: hot backup using RMAN

          I consider your snapshot method the best in terms of fast backup and fast restore (DBPiTR) as you talk about 3TB db.
          If you use RMAN for such a big databases, then think of:
          1. incremental backup with change block tracing turned on
          2. "recover copy" feature of RMAN

          details here:
          • 2. Re: hot backup using RMAN
            Hi khs,
            It all depends on what the needs are for restore.
            If you need a very fast restore to the last backup, snapshot is the answer.

            Now if someone asks you to restore the database to a point in time before the oldest available snapshot, do you recover it from tape or you just say you cann't do it?
            Or if a dbs clone is needed on a different server, what technology would you use?
            Implementing rman with a tape module could be an answer.


            • 3. Re: hot backup using RMAN
              We use Netapp FlexClone which allows us to clone a database in secs. Basically using pointers instead of physically copying files.

              We keep our snapshots for one month on disk and we rarely have to go back to tape. I could not recall when was the last time we had to go back to tape to restore a database.

              Maybe I can use RMAN in conjunction with Flashback db. Still looking into that...