Re: data guard fast start failover

From: <Laimutis.Nedzinskas_at_seb.lt>
Date: Fri, 16 Jan 2009 15:08:03 +0200
Message-ID: <OF9347801E.4BB2CE24-ONC2257540.00478C62-C2257540.00482672_at_seb.lt>



Thank you for comments.

What is interesting for me is that primary kills itself if it can not connect to both observer and standby. Appearently this is done to avoid a split brain.
I am just not sure this is a desired behavour....

                                                                           
             Ian Cary                                                      
             <ian.cary_at_ons.gsi                                             
             .gov.uk>                                                   To 
                                       Laimutis.Nedzinskas_at_seb.lt          
             2009.01.16 14:40                                           cc 
                                       oracle-l_at_freelists.org,             
                                       oracle-l-bounce_at_freelists.org       
                                                                   Subject 
                                       Re: data guard fast start failover  
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Hi Laimis,

I've just implemented this on three 10.2.0.3 systems here and it all seems fairly straightforward. Its early days so its probably too soon to say whether there are any issues or not but everything seems to be working OK so far.

Testing the failover by aborting the original primary worked smoothly and took around 4 seconds. The observer also reinstates the original primary to be the new secondary quite happily when it is remounted. End user connections are also seamlessly transitioned to the new primary without any need for manual intervention.

When you say split brain I assume you are thinking of a circumstance where both instances believe they are the primary and also have active services allowing users to connect. The documentation states that automatic fast-start failover never allows there to be more than one primary and my testing seemed to bear this out.

The synchronous nature of the log shipping can have an impact on the primary performance and a primary commit won't complete until the redo-information has been accepted by the standy by so it is pretty important to ensure that the network speed between servers is good and also that I/O speed on the secondary doesn't cause a delay in copying the log files. Other than that there should be no impact on normal activities.

Hope this helps,

Cheers,

Ian

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Hi all

Anyone's using data guard fast-start failover ? What are the experiences ?
What about split brain?
Does it interfere heavily with normal database activities? Any other comments?

Thank you in advance,

Laimis N

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Received on Fri Jan 16 2009 - 07:08:03 CST

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