A standby database maintains a duplicate copy of your primary database and provides continued availability in the event of a disaster. The standby database is constantly in recovery mode. To maintain your standby database, you must mount it in standby mode using the ALTER DATABASE statement and apply the archived redo logs that your primary database generates. You can open a standby database in read-only mode to use it as a temporary reporting database. You cannot open a standby database in read/write mode. 备库如何装载 1. 备库总是处于恢复模式 2. 备库不能以读/写模式打开[@more@]