OK, I forgot to mention that the command used to start the backup is:

db2 -z $LOG -v BACKUP DATABASE $DB2_BASE ON ALL DBPARTITIONNUMS ONLINE 
${BACKUP_TYPE} LOAD ${NMDB2_LIBFILE} OPTIONS @${NMDB2_CFGFILE} ${DB2OPT}"

so the backup is not started by a group, but by DB2, using the NMDB2_CFGFILE.

Thanks.

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