>> let me what activties can b performed on mount state ...??http://www.dba-oracle.com/t_startup_mount_tasks.htm
The docs note:
You can start an instance, and optionally mount and open a database, in restricted mode so that the instance is available only to administrative personnel (not general database users). Use this mode of instance startup when you need to accomplish one of the following tasks:
- Perform an export or import of data
- Perform a data load (with SQL*Loader)
- Temporarily prevent typical users from using data
- Perform certain migration or upgrade operations
When the startup command enters the mount stage, it opens
ad reads the control file. The control file is a binary file that tracks
important database information, such as the location of the database datafiles.In the mount stage, Oracle determines the location of the datafiles, but does not yet open them. Once the datafile locations have been identified, the database is ready to be opened.
Most folks use "startup mount" for moving to ARCHIVELOG MODE.