My question is:
- What is the database backup contains of?
all the information of the SEPM, roles, logs, groups information etc.
- Is it possible to restore version 11 backup to version 12 SEPM?
no, you need to install SEPM 11 and then restore SEP 11 Db and once completed successfully upgrade to SEPM 12.
Using 11.x disaster recovery files with Symantec Endpoint Protection Manager 12.1
http://www.symantec.com/docs/TECH162071
- All clients that has been added to the group on version 11 will be remain after the restore process?
Yes, all the group structure will remain same.