1. EXP backup: also known as Oracle logical backup, it requires a long downtime during recovery, and the archive log cannot be applied after IMP import recovery, resulting in a large amount of data loss; For a large database, EXP will be inadequate.

2. Cold backup: also known as OS backup. Although cold backup is easy to recover, it requires the database to stop for backup, which causes a long downtime. For commercial databases, this time is just used for data processing.

3. RMAN (Hot Backup): Full backup of the database can be realized like cold backup, and it will not affect the operation of the database. But the database must run in archive mode; And the backup files must be stored on the disk of the server where the database is located, or on external devices that the database server can directly access, such as disk cabinets and tape drives.

4. StandBy backup: based on the production database (primary database), create a StandBy database (standby database), and the standby database will automatically synchronize with the production database in real time. But it is in a read-only and idle state, and does not receive user connections and business processing. If the production database fails, StandBy database can be started immediately in the mode of main database to take over the work of production database. Using this backup method, the fault repair time is the shortest and the data loss is the least. However, the disadvantage is that StandBy database server must be provided separately, and the cost is relatively high. Generally, it is widely used in industries with high real-time requirements such as finance and telecommunications.