2 Replies Latest reply: Apr 9, 2013 9:19 PM by Hemant K Chitale RSS

    Max Availability

    1002021
      Hello,

      In Maximum availability mode, Transactions on the primary do not commit until redo information has been written to the online redo log and the standby redo logs of at least one standby location. If no standby location is available, it acts in the same manner as maximum performance mode until a standby becomes available again.

      1) Without commit transaction, will data loss not happen in Max Availability Mode?

      2) How archive logs maintain consistency in this mode?
        • 1. Re: Max Availability
          FreddieEssex
          1) You CAN get data loss with maximum availability, if your standby fails and then your primary continues and then your primary fails. In this scenario you will have data loss. Maximum protection guarantees no data loss but will of course shut down your primary to maintain no data loss. It is recommended to have at least two standby databases with maximum protection.

          2) What do you mean by "maintain consistency"?
          • 2. Re: Max Availability
            Hemant K Chitale
            Without commit transaction, will data loss not happen in Max Availability Mode?
            Transfer of transactions will be delayed till the Standby restarts and completes a catchup. Thus there will be a "lag". There will be data (transaction) loss if the primary goes down before the standby completes a catchup.
            How archive logs maintain consistency in this mode?
            The standby attempts to catch up with the primary when it comes up again.


            Hemant K Chitale