db2 backup

Hi,

Iam new to db2.In oracle if we change the archive set to ON,then we can take both online and offline backup and if we set archive to OFF then we cannot take online backup.

1)Is the same way in db2 also?once we change from circular logging to archival logging then archive is ON so can we take both online and offline backup?

2)offline backup is greyed out in dbacockpit.how to enable?

3)From dba cockpit if i take online backup,there is one option include log file.What is the log files ?is that the secondary log file ie archival folder.so every time if we take backup,it will take the whole archive folder everytime.

Pls guide me in this