Oracle data synchronization in live environment

What are known reliable tools for syncing huge amounts of data between Oracle DB instances in live environment?

Requirements are that the host with live data is running in a live environment, i.e. the database is updated. Receiving host is offline, and will go online only when data sync is complete.

Most of the data is stored in blob columns and amount of data to sync reaches ~100GB. Only part of data from a table needs to move, while the actual size of the table is around 50 TB.

This is a clustered system, and each live machine is a clone of the other, each machine contains an instance of Oracle DB. Sometimes machines need to go under maintenance and they lose live data. When they come back up, the data needs to be synchronized. Machine is brought offline for maintenance usually not longer for 6 hours. Without having clone machines, we would not be able to ensure that system is up, when one of the machines must go for maintenance.

S开发者_JS百科ync should not severely influence the live machine CPU usage.

First thing to look at is Oracle Advanced Replication and Oracle Streams. You might want to consider getting a good book on Streams.