????PHASE1:nomount???. ???????????????backupground_dump_dest?μ?   alert_sid.log??background processes ??trace files.

????PHASE2:mount????????control file.

????control file?д??????????:

Database name and identifier
Time stamp of database creation
Tablespace names
Names and locations of data files and redo log files
Current redo log file sequence number
Checkpoint information
Begin and end of undo segments
Redo log archive information
Backup information

?????????????PHASE0??????????????PHASE3????open??Щ???????????Oracle(???????????control file?У??????????PHASE2?У?control file??open????)??????????file location.

???????????alter database??data file clause??log file clause??rename ??????????control file??????Oracle????PHASE3???????file location???????????.

????PHASE3:open??δ????з?offline??data files??redo log files.

???????????????.???????????????offline??????offline???????rename????.?????????????control file?е???????????Oracle:File location has been changed.