(da0:umass-sim0:0:0:0): CAM status: SCSI Status Error

[Pol Hallen]

Hi all :-) I use 9.2-release, I attached an external usb drive (2Tb with 
ext3 fs), I mounted it with:

mount /dev/da0s1/ /path

everything ok

I don't know when and why, after some time I see:

(da0:umass-sim0:0:0:0): READ(10). CDB: 28 00 00 00 08 80 00 00 10 00
(da0:umass-sim0:0:0:0): CAM status: SCSI Status Error
(da0:umass-sim0:0:0:0): SCSI status: Check Condition
(da0:umass-sim0:0:0:0): SCSI sense: UNIT ATTENTION asc:28,0 (Not ready 
to ready change, medium may have changed)
(da0:umass-sim0:0:0:0): Retrying command (per sense data)
(da0:umass-sim0:0:0:0): READ(10). CDB: 28 00 00 00 08 80 00 00 10 00
(da0:umass-sim0:0:0:0): CAM status: SCSI Status Error
(da0:umass-sim0:0:0:0): SCSI status: Check Condition
(da0:umass-sim0:0:0:0): SCSI sense: UNIT ATTENTION asc:28,0 (Not ready 
to ready change, medium may have changed)
(da0:umass-sim0:0:0:0): Retrying command (per sense data)
g_vfs_done():da0s1[READ(offset=8192, length=8192)]error = 6

and mount point become dead

any idea?

thanks for help!