Hello
Does one need to take backup of DB as well as filesystem (CI export) for offline backup of a JAVA system?
You cannot club file system data ( /usr/sap/SID ) along with the database backup as most of the databases are backed up using the database specific tools (mostly). If you are taking an export using sapinst then you can club together.
For a Java stack you need to backup the file system data as J2EE stacks hold data (especially the configuration and settings) in the database as well as at the file system level.
When you take an export of the Java stack you can either take an export of the Java schema along with the file system data or just the file system data and the database can be restored using the database specific method while doing the import.
Regards
RB