Hammer, usb disk, SYNCHRONIZE CACHE failure

[Joe Talbott]

This is for 2.2-RELEASE.  I have a 2.5" drive in an external USB
enclosure with one big Hammer filesystem on it.  The disk is ~75GB.
When the daily cronjob to cleanup hammer runs it fails with these
errors:

Thanks,
Joe

Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): SYNCHRONIZE CACHE(10). CDB: 35 0 0 0 0 0 0 0 0 0 
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): CAM Status: SCSI Status Error
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): SCSI Status: Check Condition
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): ILLEGAL REQUEST asc:20,0
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): Invalid command operation code
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): (da0:umass-sim0:0:0:0): 
SYNCHRONIZE CACHE(10). CDB: 35 0 0 0 0 0 0 0 0 0 (da0:umass-sim0:0:0:0): ILLEGAL REQUEST asc:20,0
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): Invalid command operatio n code
Apr  6 03:02:10 jupiter kernel: Unretryable error
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): error 22
Apr  6 03:02:10 jupiter kernel: (da0:umass-sim0:0:0:0): Unretryable Error
Apr  6 03:02:10 jupiter kernel: HAMMER(DATA): Critical error inode=-1 while flushing meta-data
Apr  6 03:02:10 jupiter kernel: HAMMER(DATA): Forcing read-only mode
Apr  6 03:02:10 jupiter kernel: HAMMER(DATA): Critical write error during flush, refusing to sync UNDO FIFO