Three modes of Data Guard

Three Data Guard Modes: Data Guard Protection mode (Data Guard Protection Modes) for Data Guard, its survival logic is very simple, because it provides three Data Protection Modes, we call it another kind: There are three models: Maximum protection: This mode ensures no data loss. There is a price to implement this step. It requires that all transactions be written into the local online redo log before committing, it also submits the standby redo log to the standby database at the same time, and confirms that the redo data is available in at least one standby database (if there are more than one) before it is submitted on the primary database. If any fault occurs that causes the standby database to be unavailable, the primary database will be shut down. Maximum performance: This mode provides the highest level of data protection policies without affecting the performance of the primary database. Transactions can be committed at any time. The redo data of the current primary database also needs to be written to at least one standby database, but such writing can be non-synchronous. If the network conditions are ideal, this mode can provide data protection similar to the highest availability, but only has a slight performance impact on the primary database. Maximum availability (Maximum availability): This mode provides the highest level of data protection policies without affecting the availability of the primary database. The implementation method is similar to the maximum protection mode. It also requires that all transactions ensure that redo data is available in at least one standby database before committing. However, if a fault occurs during the import, the standby database redo log cannot be written at the same time, the primary database will not shut down, but will be automatically converted to the highest-performance mode. After the standby database returns to normal, it is then automatically converted to the highest availability mode. First, you need to understand the oracle execution method. For example, after a data operation, such as inserting a data row, oracle will not immediately execute it in the database. Instead, write your SQL statement into the log (which can be understood as a redo log), and then upload a log to the slave database. After data guard is enabled, the three modes are actually what happens when the redo log cannot be uploaded to the slave database. The maximum protection means that when the redo log cannot be uploaded to at least one slave database, this command is not executed on the master database. This mode has the lowest performance, but is the safest. The maximum performance is that the master database will execute this command no matter whether the redo log can be uploaded to at least one slave database. This mode has the highest performance, but is the least secure. Maximum availability. When the redo log can be uploaded to at least one slave database, the maximum protection mode is the same. However, if it cannot be uploaded to at least one slave database, the command is automatically executed in the maximum performance mode. In this mode, the performance and security are intermediate. Maximum protection and maximum availability require at least one standby database redo data to be written synchronously. You must specify the LOG_ARCHIVE_DEST_n initialization parameter for all three modes.