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Why is the controlfile created with strange name?



I recenlty got a question, why is this happening. Well, the situation is not so difficult, but also not trivial.

As we all know, the location and the name of the controlfiles are defined with Oracle parameter 'control_files', like below:

So while (re)creating the controlfile, the Oracle Instance is using the above information to place the controlfiles in the right place with the right name.

But, what happens if the 'control_files' parameter is not maintained in (s)pfile or commented out while recreating the controlfiles?

As we can see, a single controlfile was created with a very srange automatically generated name in flash recovery area. This is the so called Oracle-managed controlfile.

The conclusion is that there is a predefined internal rule of Oracle Instance how to act in different scenarious. In my case, since the 'control_files' parameter wasn't maintained in (s)pfile, it took the control and created the file based on some internal algorithm.

This is already documented by Oracle, howewer not with real examples.

Oracle® Database SQL Language Reference 11g Release 2 (11.2)




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