ZFS with USB "SCSI"

Hi has anyone used ZFS with a external USB drive. I seem to get ZFS trying

The disk is mostly empty so these write errors are mostly at the beginning.
Is there a problem with UMASS and ZFS or should I update my
7.0-CURRENT(about 2-3 weeks old). I used to have a UFS filesystem on
this drive and it
worked flawlessly. ZFS sometimes silently ignores most of these errors but
when I start copying lots and lots of files it gives a lot of errors and
Panics.

... a bunch of errors like these:
Jun 12 17:12:15 redqueen root: ZFS: vdev I/O failure, zpool=WDPassport
path=/dev/da0s2d offset=4260626432 size=131072 error=5
Jun 12 17:12:15 redqueen root: ZFS: vdev I/O failure, zpool=WDPassport
path=/dev/da0s2d offset=4260757504 size=131072 error=5
Jun 12 17:12:15 redqueen root: ZFS: vdev I/O failure, zpool=WDPassport
path=/dev/da0s2d offset=4260888576 size=131072 error=5
Jun 12 17:12:15 redqueen root: ZFS: vdev I/O failure, zpool=WDPassport
path=/dev/da0s2d offset=4261019648 size=131072 error=5
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a
0 2 f6 4f 9e 0 0 80 0
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): CAM Status: SCSI
Status Error
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): SCSI Status: Check
Condition
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): ILLEGAL REQUEST
asc:21,0
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): Logical block
address out of range
Jun 12 17:12:15 redqueen kernel: (da0:umass-sim0:0:0:0): Unretryable error
Jun 12 17:12:15 redqueen root: ZFS: vdev I/O failure, zpool=WDPassport
path=/dev/da0s2d offset=4261150720 size=131072 error=5
Jun 12 17:14:02 redqueen syslogd: kernel boot file is /boot/kernel/kernel
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a
0 2 f6 4d 9e 0 0 80 0
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): CAM Status: SCSI
Status Error
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): SCSI Status: Check
Condition
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): ILLEGAL REQUEST
asc:21,0
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): Logical block
address out of range
Jun 12 17:14:02 redqueen kernel: (da0:umass-sim0:0:0:0): Unretryable error
Jun 12 17:14:02 redqueen kernel: panic: ZFS: I/O failure (write on <unknown>
off 0: zio 0xffffff00240db000 [L0 ZFS plain file] 20000L/20000P
DVA[0]=<0:fd9a0000:20000> fletcher2 uncompressed LE contiguous birth=2447
fill=1
cksum=5df9a1c34a151f29:ef04006d2a7312e2:f22e3b20440a3f6:c154faf2be8dc79d)
Jun 12 17:14:02 redqueen kernel: cpuid = 0
Jun 12 17:14:02 redqueen kernel: Uptime: 46m5s
Jun 12 17:14:02 redqueen kernel: Physical memory: 881 MB
Jun 12 17:14:02 redqueen kernel: Dumping 220 MB: 205 189 173 157 141 125 109
93 77 61 45 29 13
Jun 12 17:14:02 redqueen kernel: Dump complete
Jun 12 17:14:02 redqueen kernel: Automatic reboot in 15 seconds - press a
key on the console to abort
Jun 12 17:14:02 redqueen kernel: --> Press a key on the console to reboot,
Jun 12 17:14:02 redqueen kernel: --> or switch off the system now.
Jun 12 17:14:02 redqueen kernel: Rebooting...

-- 
Ali Mashtizadeh
علی مشتی زاده