Oracle Data Guard Protection Modes for non-DBAs

Oracle Data Guard offers three different types of data protection modes – Maximum Performance, Maximum Availability and Maximum Protection. The names that Oracle has chosen to describe the protection modes may be confusing. If you need to explain the protection modes to the technical management team, then the following terminology may help you.

Asynchronous

• Primary database transactions (redo information) are replicated asynchronously to the standby database with respect to the primary database transactions.
• Transactions are confirmed as committed as soon as they are written to the disks on primary server.
• Commit Performance on the primary is solely dependent upon the performance of the primary database and server.
• This protection mode has minimal impact on the performance of the primary database.
• This protection may incur minimal data loss.
• Default Protection mode

Synchronous, Best Efforts

• Primary database transactions (redo information) are replicated synchronously to the standby database with respect to the primary database transactions.
• If standby database becomes unavailable, then Oracle falls back to asynchronous protection mode.
• Transactions are confirmed as committed as soon as they are written to the disks on primary server and secondary server.
• Commit Performance on the primary is dependent upon the performance of the primary database and standby database. Commit Performance also depends upon the network latency between the primary and standby databases.
• This protection mode has impact on primary database performance as COMMITs are completed only when transactions are confirmed as written on the primary and standby servers.
• This protection mode offers no data loss as long as standby database is available.

Synchronous

• Primary database transactions (redo information) are replicated synchronously to the standby database with respect to the primary database transactions.
• If standby database becomes unavailable, then the primary database hangs.
• Transactions are committed as soon as writes to the disks on primary and secondary are completed.
• Commit Performance on the primary is dependent upon the performance of the primary database and standby database. Commit Performance also depends upon the network latency between the primary and standby databases.
• This protection mode has impact on primary database performance as COMMITs are completed only when transactions are confirmed as written on the primary and standby servers. In addition, the primary database may hang if the standby database becomes unavailable.
• This protection mode offers no data loss