Solution : https://service.sap.com/sap/support/notes/216010 (SAP Service marketplace login required)
Key words : 
/    important general remarks    ii/   free space requirement, db2/390 migration/upgrade    vi/   problems, /    important general remarksthis note, additional key words update, select distinct 'drop table, includes db2foros/390-specific problems, guidelines    iv/  errors, phase tabim_<rel>, /3 upgrade    ix/  history----------------------------------------------------------------------, database    iii/  correction
Related Notes : 
       
| 338276 | Additional information: Upgrade to BW 2.1C | 
| 213865 | Additions to upgrade to BW 2.0B |