DB2 managed to confuse me again

user_a is logged on to the win3k server running db2v9.
user_a has dbadm auth.
So when user_a wants to create a new tablespace this is not permitted.
That's right and user_a issues the command "db2 connect to abc user db2inst1 using db2inst1" and tries to create the tablespace again. Now it works as designed
Next, after a load, a tablepace backup is required. The connection is still valid but the backup fails with a SQL1092 because user_a is not authorized.

Okay, still sane. What I do (and I remember that from db2 classes):
But still the same error occurs. DB2 evaluates the credentials of user_a instead of db2inst1, the id who is attached to the instance.

Am I mistaking?

If you check the manual, you can see that
Clearly, it will use the credentials of the user that is logged in (user_a).

My mistake then, but what is the use of "attach to instance user another_user" if you cannot do anything with those credentials?

You can, when you need an instance attachment.

Authorization (for Backup)

One of the following:

- SYSADM
- SYSCTRL
- SYSMAINT

DBADM is not included.