Found another solution: If i use gbak -GARBAGE_COLLECT everything works,
i can backup the database.
OK, some words of the data history:

1. Inserts 2.500.000 records into the table
2. Delete this 2.500.000 records
3. Insert 4.500.000 record again

After this i want to backup and restore the database to make a garbage
collection. So the using gbak -g is ok in this case.
But why do the engine hang while making an garbage collection in the
database?

Any idea?

Henner.