Oracle Instance Management

1. Database Startup and Shutdown

• Database Control - A tool for managing one database even though the database can be clustered.

• If there are several databases then each database must have its own instance of the database control.
• All communications to DB Control id thru HTTPS.
• DB Control Configuration done at DB creation time - hostname and TCP port
  
• Start DB Control - emctl utility: emctl start dbconsole, emctl stop dbconsole, emctl status dbconsole. ORACLE_HOME, PATH and ORACLE_SID must be set for these cmds to run - for configuration settings.
  
• emctl status dbconcole will give the port on which the DB control is listening.
• Logon window will show only if the listener is running.

Starting the Listener

• Requests to listener uses Oracle Net
• To start DB Listener: With the lsnrctl utility, using DB control, or as a service(Windows)
• lsnrctl start [listener], lsnrctl stop [listener]

Starting SQL*Plus

• sqlplus /nolog then sqlplus /as sysdba sqlplus /as sysoper, etc.

Database Startup and Shutdown

• A DB is mounted and opened or dismounted and closed.
  
• Through SQL*PLUS: startup, shutdown or through DB Control.
• Alert log will give details of such operations - bcoz are critical operations.
• Can also be carried out by privileged users.

Connecting with Approprite Privilege

• Ordinary cannot start DB because they are authenticated against the Data Dictionary and DD cannot be read unless the DB is opened.
• Login thru Operatins System or external password file.
• DD Authentication: connect username/password. Anyone connecting this way cannot issue startup or shutdown.
• Password file or OS Authentication: Passwd File Auth - connect user/pass as sysdba, connect user/pass as sysoper, OS Auth - connect /as sysdba, connect /as sysoper.

SYSOPER and SYSDBA

• Special privilege with special capabilities
• Enabled only when an external auth means is used - Passwd file or OS.
• SYSOPER cannot CREATE DATABASE nor do incomplete recovery nor create SYSOPER and SYSDBA users.
  
• Both SYSOPER and SYDBA can: STARTUP, SHUTDOWN, ALTER DATABASE MOUNT|OPEN|CLOSE|DISMOUNT, ALTER [DATABASE|TABLESPACE] [BEGIN|END] BACKUP RECOVER
• show user cmd show the logged on user.
• SYSDBA logs you on as SYS user, SYSOPER logs you on as PUBLIC - a notional user with administration privileges.