Startup Mount Problems

In the test group at this morning, a friend raised an oracle question, mainly because an error occurred during startup mount. He sent a screenshot to me, and the error message was ????, There is no complete error description, so I suggest asking him to find the error from the Alert Log File. The log file is still ???, I thought it was a TXT encoding problem, so I saved another copy and changed the encoding format ???. This problem is still not solved. But it doesn't matter. Oracle error numbers appear in the error log, so I asked him to get the meaning of those error numbers on Google. Since he is learning about Linux, other things will be solved by himself. Finally, he found that the control01.ctl control file was incorrect and copied a copy to solve the problem. I should have located this issue myself and have learned it before. Now I will summarize the following:

When Oracle uses startup mount, the system background process needs to read two files: spfile and controlfile. Then, find the data file based on the two files to make Oracle open. When mounting, an error occurs. The most likely is the spfile and control file. In this case, you need to go to the Oracle directory to check whether the two exist completely. When an error occurs during the startup open state, there will be more problems, which may be a database recovery problem. At this time, the most important thing to do is to open the Alert Log File and query the error number, solve the problem according to the actual situation.

Summary: Oracle log files are very important. When you encounter problems, first check what problems he prompts, and then sort out the solutions to the problems.