Just like to mention that at least ubuntu 7.10 (gutsy) comes with a
broken db2 updater.
If you have already installed DB2 9.0 using the ubuntu packages the
updater will break your running instance as it replaces 9.0 with 9.5,
breaking the old instance "db2inst1" and introducing a second (running)
instance "db2inst2".
Here is the link to the full bug description including a first short
workaround to possibly get your data back without restore:
https://bugs.launchpad.net/bugs/189538
regards,
Norbert