2 Replies Latest reply on Apr 20, 2011 2:09 AM by Hemant K Chitale

    DB Replication and (Hot Backup + Suspend)

      We use the storage replication technologie (block level) to replicate a database to our DR site. The script like any other data replication is very simple

      Create the replication session (storage action)
      Put DB is hot backup mode (oracle action)
      Start the session and the checkpoint (storage action)
      Put DB back in normal mode (oracle action)
      Mount the replicated file system on the DR server to check (storage action)

      Now my storage vendor asked me to put the alter system suspend and alter system resume after the hot backup mode and before the normal mode to ensure that there is no I/O when the storage checkpoint is performed.

      I want your thought on that. I never used those suspend/resume before (knew that it exis) but it always worked fine without. The oracle documentation explain what those commands do but not why it exist and in which situation you want to use it.

      Also, in suspend mode, I/O are blocked, which affraid me a bit if the replication script failed in the checkpoint phase and leave the DB in that mode. Pretty sure everything will hand quickly.

        • 1. Re: DB Replication and (Hot Backup + Suspend)
          We use EMC's SRDF technology to replicate one of our DB, and we do not use suspend/resume.

          You may check metalink /ID 340305.1) and Tom Kyte (http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:373618158622), both says that if your hardware vendor tells you to do it, do it :)


          Gokhan Atil
          • 2. Re: DB Replication and (Hot Backup + Suspend)
            Hemant K Chitale
            Use SUSPEND and RESUME if your storage hardware vendor requires this.

            If the storage implementation is such that your database filesystems are on LUNs which happen to not really get snapshotted at a consistent point in time (i.e. as an atomic operation) you may lose write-ordering.

            So, the requirement to SUSPEND/RESUME is based on how the Snapshot/Clone technology is implemented in the storage.
            Note : The BEGIN BACKUP and filesystem 'sync' commands are also necessary !!

            Hemant K Chitale