I cannot login as the db2 user....
You need to login as db2 user. The restore will only work if done by same user that performed the backup.
See the following in NBU for DB2 Admin Guide: http://www.symantec.com/docs/DOC5166
About an alternate restore (topic starts on p. 90)
p. 91: Table 4-5 Types of restores permitted
p. 93:
To perform an alternate restore of a DB2 database
1 Modify the db2.conf file on the destination client.
Add the following new object identifiers:
■ One to specify the alternate restore
■ One to define the new database
■ One to define the old database
■ One to define the new log files
■ One to define the old log files
The following example shows the keyword lines that are needed to specify the alternate restore:
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*** NOTE ****
I am not a db2 dba. As a backup admin, I'm not expected to have any dba skills.
For this reason, I would sit with the local db2 dba and expect him/her to assist.