Special Parameterization files (SPFILE)
All the changes that are made requires a reboot of Oracle database. In order to change certain parameters SPFILE is maintained.
We need to explicitly create SP file this SP File cannot be edited manually E:\ORACLE\QAS\I02\ADMIN
When Oracle is started the database available for users.
Commands
Startup open
Startup mount
Startup no mount.
Oracle contains 3 Modes (4 Including Restrict)
1. Startup Nomount : This phase is used to create control files and database. No datafiles are mounted.
2. Startup Mount: We can start a DB and mount a database without opening it, allowing us to perform specific maintenance operation.
a) Change the archive log mode status
3. Startup Restrict:
a) Perform an export or import of database data.
b) Perform a data load (With SQL * Loader)
c) Temporarily prevent typical users from using data
d) During certain migration and upgrade operations
e) Used during patch applications the database is opened but not allowed i.e. restricted to the above operations. End uses cannot perform any tasks.
4. Startup Open: When DB is started using startup cmd. It reads the init parameters in the following sequence.
1) SPFILE<SID>.ORA
2) SPFILE.ORA
3) INIT<SID>.ORA
4) INIT.ORA
You can view more tutorials about SAP BASIS