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Oracle Data Guard Architecture for Multiple Standby Database
In case I am setting up an Oracle Data Guard system which requests multiple standby database copies. What is the maximum number of standby copies can be supported by the primary database from performance consideration? What is the best practice if I need multiple standby copies, for example 8?
Anonymous
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May 14th, 2012 01:00
firstly, for the maximum number of standby: Oracle 11gR2 has increased the number of manageable standby databases from only nine to a total of thirty.
secondly, take performance into consideration, you need to think about the protection mode. there're three modes: Maximum Availability,Maximum Performance, Maximum Protection. with Maximum performance, it provides the highest level of data protection that is possible without affecting the performance of a primary database. refer to http://docs.oracle.com/cd/E11882_01/server.112/e25608/protection.htm#CHDEDGIF for detailed explaination on this.
BTW, personally, I don't think there're any best practices on standby db numbers, as it depends on a lot of things, workload, network, etc..
zhaos2
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May 14th, 2012 22:00
Thanks Betty for your research!
Maximum performance protection mode (the default) will allow a transaction to commit as soon as the redo data needed to recover that transaction is written to the local online redo log. The primary database's redo data stream is also written to at least one standby database, but that redo stream is written asynchronously with respect to the transactions that create the redo data. So the primary database performance impact is minimized.