Physical Standby and Redo log

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Physical Standby and Redo log

Postby baseballGuy » Fri Nov 09, 2012 2:05 am

Hi Tim,

I have couple questions about redo logs and standby logs and real time apply......

1. when I created redo logs without THREAD, how does Oracle create the thread? I don't understand why some logs are THREAD 0 and some logs are THREAD 1. In order to use the same THREAD, let's say 1. I have to add THREAD 1 to create logs command, I don't understand.......

2. When I used standby logs as opposed to ARCH, if I need to FAILOVER one day, do I have to issues any extra command for recovery? or it's prettty the same as ARCH?

Thanks Tim
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Re: Physical Standby and Redo log

Postby Tim... » Fri Nov 09, 2012 10:01 am

Hi.

The thread is the instance. If you do not specify a thread, Oracle assumes you mean the current instance and uses the instance number. In a RAC installation, you need to create redo logs for each instance (thread).

You use standby redo logs in addition to archived redo logs. The point is, when using standby redo logs you don't have to for an archive switch to have the redo transported to the standby database. This keeps the standby more up to date than just using archived redo logs. This is all seamless to you in the event of a failover. There are no additional steps to take.

Cheers

Tim...
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Re: Physical Standby and Redo log

Postby baseballGuy » Mon Nov 12, 2012 4:26 pm

Thanks Tim for the clarification.

I have to more questions based on the fact that I have single instance:

1. when I didn't specify the thread, why did Oracle sometime use Thread 0 and sometime it used thread 1?

2. Due to the fact, I have single instance, it should be ok if I specify thread ! on all of my redo and standby logs, right?


Thanks again tim
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Re: Physical Standby and Redo log

Postby Tim... » Mon Nov 12, 2012 4:53 pm

Hi.

I would expect a single instance database to have an instance number of 1, so all redo logs should be in thread 1.

I have no idea why it might be creating them with thread 0. Can't say I've ever seen that before. I would create new ones as thread 1 and get rid of the thread 0 logs.

Cheers

Tim...
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