Best method to do DB2 Offline Backup's

db2 connect to <database_name>
db2 quiesce database immediate force connections
db2 terminate
db2 deactivate db <database_name>
db2 backup db <database_name> to <directory_path>
db2 connect to <database_name>
db2 unquiesce database
db2 terminate

I suggest you to follow the above steps if you have a application server which has retry logic and attempting to make a connection to the database all the time.