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Nomount stage

Oracle starts the nomount process he will load the parameter file (spfiledid.ora spfile.ora initsid.ora and then allocate memory according to the parameters will open the alert file to write the log)

> startup nomount

> show parameter spfile # if there is a value, this is spfile startup

> select name,value from v$parameter where name='spfile' # if there is a value, spfile starts

> ho rm / dbs/spfileorcl.ora # this error will be reported if you delete this file and start the database

> startup force nomount

Ora-01078:failure in processing system parameters # will have such an error

You need to find the backup spfile file to pull up the database.

> startup pfile=xxx/initorcl.ora nomount

Create the spfile file after pulling up the database

> create spfile from pfile='xxxx/initorcl.ora' # this creates the spfile file

This oracle startup just starts the instance, starts the acquired process, and allocates the memory of the SGA in the nomount phase.

Parameters can be modified in the nomount phase (database load phase)

After the above nomount phase is complete, you can execute the mount phase.

> alter database mount # this is to open the database to the mount stage

The startup database of the mount phase will read the control file.

> show parameter control_file # this is the control file

The mount phase can manipulate the physical structure of the database:

Alter database instruction

Enable and disable redo log archiving

Perform database recovery

Create database instruction

Drop database instruction

Database opening phase:

Determine whether the data file exists

Determine the status of the database file

Open online data file

Open the online redo log file

> alter database open # this is to open the database

> select open_mode from vault database; # this is the current status of the query data

The instructions to start are as follows:

Startup [force] [open] [pfile=xx] [nomount] [mount] [restrict] [revover]

[database]

Open: enables users to access the database

Mount: Mount the database for some DBA activities but do not allow access to the database

Nomount: create SGA and start background processes but do not allow access to the database

Pfile=xxx: allows configuration routines using default parameter files

Force: enforcement

Restrict: only users with restrict session privileges are allowed to access the database

Recover: start meson recovery when you start the database

Shut down the database

Is to write change redo log entries in the buffer cache to the data file and the online redo log

Close all online data files and online redo log files

Uninstall the database

Close its control file

Close the instance

Alert files and trace files will be closed

The SGA is reclaimed and the acquired process is terminated

Shutdown [normal | transactional | immediate | abort]

For more information, please go to the personal blog address:

Http://www.oracleandmysql.com/article-detials/1

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