On 12/20/2015 04:39 PM, kathryn axelrod wrote:
Adding to what Andrew said, real time apply sends online log info..this may be sent anyway depending on other configs.There is a significant performance penalty for both maximum availability and maximum protection. Most of the places I've seen run in maximum performance mode. The choice depends on the business needs.
With max performance, it sends online log info when it's comitted on the primary..but the primary pays no attention to when the standby applies it.
You may want to consider switching to max availability with at least one standby using sync/affirm. It is a compromise between absolute 0 data loss and no primary downtime with minimal primary waits.
With max availability, as long as a standby is available, it sends info to the standby as soon as it's comitted to the primary's online log. (If no standby is available, it temporarily switches to max performance so the primary can continue).
With async/ noaffirm, the primary waits for the response that that standby received the data. Sync/ affirm = wait to hear the standby Applied the data.
Alternately, with max protection, it is 0 data loss..but the primary may shut down when it doesn't get a data confirmation from the standbys.
https://docs.oracle.com/database/121/SBYDB/protection.htm#SBYDB4743
