Oracle startup Details description
nomount
Mount
Open
Use the sys user login
startup nonount;
alter database mount;
alter database open;
1.startup nomount
At this time, the database is not loaded, this time to do the following database:
Reading the parameter file, the default path $ ORACLE_HOME / dbs / spfile <sid > .ora
If you can not find the default parameter file in the default path is hierarchically below to find the file until you find, stop looking for the next level.
spfile<sid>.ora - spfile.ora - init<sid>.ora - init.ora；
If none are found, an error. Can not find the parameter file solution to be determined, will be updated after the home link.
The parameter assignment sga parameter file;
Starts a background process;
Open the .log alert log and trace files alert_ <sid>;
2.alter database mount;
At this time, completion of loading the database
Examples of the database associated with the start; example only memory structures, database both data files.
Find the control file location and open the parameter file;
If you can not control files in the specified path, it will error, the solution to be determined, after the update will add links.
Read from the control file and data file name and state redo log file, the data file does not check this time whether the redo log file exists, just read.
3.alter database open;
At this time, the database will be opened
Open the data file;
Open redo log file, if you have turned on archive mode;
In the final phase, Oracle database to verify the data files and redo log files to open and examine the possibility of consistency of the database, if inconsistent, SMON background process will start instance recovery.