How do you know, I am trying to improve my english, so if I made mistakes in my text, sorry.
Today, we will talk about protection mode of the dataguard.
Oracle’s have 3 mode’s of protections to dataguard.
Maximum Performance – This is the default mode. If the standby is off, the operation on the primary continue normaly and will send the information to standby redo’s according to standby availability. It’s a Asynchronous actualization. This protection mode is not ensure zero data loss.
Maximum Availability – Performs the operation on the primary and sends the information to the standby. The end of the transaction on the primary occurs when sending the information to standby redo’s. Only the end to send it’s necessary. Apply depends on standby availability.
Redo information has been sent to standby. After that, the standby sends a message to primary to notify that have received the information. The transaction continues on the primary and the information is applied on the standby as soon a possible.
If the standby is not available, the primary will bbegin to function as a maximum performance mode for preserve the on the primary. This protection mode ensures zero data loss.
Maximum Protection – It execute the operation in primary and standby. The end of transaction in primary it depends the end of transaction in standby too (send and apply). If the transaction not ended in standby, the primary stay waiting and this can create a big problem to database. It’s a Synchronous actualization.
This protection mode ensure zero data loss. For guarantee this, the primary database will be shutdown if the standby redo’s cannot write on standby.
That’s it, simple and objective. If you want more information, please, read the manual: “Data Guard Concepts and Administration” .
See you on next post.