Tuesday, July 18, 2006

New RAC demos on Oracle By Example

A new demo viewlet has been added to the very handy collection of demos for Oracle 10gR2 REAL APPLICATION CLUSTERS in the Oracle By Example series.
It shows how virtual IPs are used.
The man behind these nice little demos is Jean-Francois Verrier.
He designs a number of Oracle's core courses which are delivered by Oracle Education.


At Tue Jul 18, 05:27:00 PM, Blogger Alex Gorbachev said...

Hi Lutz,

I think it's a bit of misunderstanding. What is described there is purely VIP feature of CRS but it has nothing to do with FAN technology. In fact, there is no even a FAN event that directly reports VIP failures and recoveries.

Nevertheles, the demo is nice simple explanation of how VIPs work. However, what is missed in that demo is the purpose of VIP and why this complication is required. Would be useful to have a comparison of what happens without VIP and with VIP.

The point not covered is that the VIP feature of CRS allows to avoid TCP timeout which is depending on the platfrom default might be as high as 10 minutes. In this case, new connections will hang for a while until TCP timeout is reached and only than swith to another one. Existing connections might also be hanging for a while until failure is detected. So VIPs are implemented in CRS to overcome this problem. Before 10g CRS it had to be implemented with third party clusterware products.


At Wed Jul 19, 07:33:00 AM, Blogger lutz_hartmann said...

Hi Alex, you are fast in discovering!
Thank you for your comment, I have changed the post in order to make it less missleading.
Thank you also for your good additional information on VIPs.

At Wed Jul 19, 08:31:00 PM, Blogger Alex Gorbachev said...

I also wrote to Jean-Francois and he mentioned that it might be a good idea indeed to show benefit of VIPs by the way of comparison. Perhaps, the demo might be even updated. Would be cool!

At Thu Jul 20, 07:38:00 AM, Blogger lutz_hartmann said...

Cool, I also contacted him to tell him that some of the intervals in the demo are a little short and that it is difficult to follow up with reading. So it is a good idea to update it anyway I think. But still I like these demos very much and I hope that there will be more comming up. I will post the news as soon as there will be new demos.


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