We are off maintenance, so I can't turn this in directly to IBM, but I know 
some of their best and brightest watch this list.  I've got a consistent case 
where a backupset being generated hangs if an expiration starts during it, 
after which neither process will finish cancelling even after several hours.  
I've got my workaround in place - move nodedata to get the node all on 
quick-access storage and comment out expirations until it's finished, but it's 
been a hassle getting to that association.  I'm looking at
17      GENERATE BACKUPSET      ANR3507I Cancel in progress
27      Expiration      Examined 11 objects, deleting 0 backup objects, 0 
archive objects, 0 DB backup volumes, 0 recovery plan files; 0 errors 
encountered. ANR0819I Cancel in progress
until the current client operations finish, after which I'll restart, manually 
complete the day's maintenance, and get some disk volumes migrated.  If I hear 
from an IBM tech who would like any diags from a recreation soon, I'll do it.  
Else, I'll do my workaround.

I had another backupset doing the same, but got it generated between 
expirations.

73,
Tim Conway
JBS USA | 1770 Promontory Ci | Greeley, CO 80634| USA
Direct: 970-506-7998  | Fax: 970.336.6195
email: Timothy.Conway AT jbssa DOT com<mailto:Timothy.Conway AT jbssa DOT com>
JBS Server Team