The differences in the 3 startup stages for oracle db are as below.
NoMount Stage:
When DB is in the nomount stage, oracle first opens and reads the
initialization parameter file "init.ora" for the DB configuration which
includes various parameters required for initialization. Based on the
parameters, the memory areas in database instance are allocated and db
background processes are started. The instance then starts.
Mount Stage:
When DB is in this stage, it opens and reads the control file which
contains the physical structure of db like the database datafiles etc..
It determines the location of the datafiles and the database is ready
to be opened.
Open Stage
When DB is in this stage, it opens the database, it tries to access all
of the datafiles associated with the database. Once it has accessed the
database datafiles, it makes sure that all of the database datafiles are
consistent.
After that DB is into normal operations state.
No comments:
Post a Comment