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Data Guard – Data Guard standby databases provide standby databases for failover in system that do not have a high downtime cost. In a data guard failover, the last redo log must be applied (up to 20 minutes to re-open the standby database), and if the last redo cannot be recovered from the crashed instance, the most recent updates may be lost.
Oracle Streams – Oracle Streams allows near real-time replication and support for master-to-master replication. Oracle Streams has no licensing costs (RAC costs extra) and it is less complex to configure than a RAC database. This disadvantage over RAC is that there is no continuous availability, update collisions may occur, replication is not instant, and application failover is usually done manually. |
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楼主: charles_gao
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发表于 2008-9-1 16:02
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