USB umass external drive problem

Hi,

I have an external USB SATA drive chassis but the drive is
only seen(*) if it is connected at bootup.  Regardless of
whether it was connected at bootup time or not, if it is
reconnected after the system is up it will not be seen.

(*) /dev/da0 will be created, but no entries for da0s1,
     da0s2, da0s3[a-g].  s1 is FAT16, s2 is NTFS, s2 is
     FreeBSD with partitions a-g.  s1, s2, and s3[a-g]
     entries are only created if the device is attached
     at bootup.

Before the drive was formatted as above (it was new without
any slice/partitioning), fdisk and disklabel would also be
unable to see the drive unless it was attached at bootup
time.

# uname -a
FreeBSD rigel 8.0-CURRENT FreeBSD 8.0-CURRENT #1 r191822: Wed May  6 02:44:45 EDT 2009 
root_at_rigel:/opt/FreeBSD/svn/obj/opt/FreeBSD/svn/src/sys/rigel  i386

Attach messages from log:

   root: Unknown USB device: vendor 0x04fc product 0x0c15 bus uhub4
   kernel: ugen4.2: <Sunplus Technology Inc.> at usbus4
   kernel: umass0: <Bulk Only Interface> on usbus4
   kernel: umass0:  SCSI over Bulk-Only; quirks = 0x0000
   kernel: umass0:3:0:-1: Attached to scbus3
   kernel: da0 at umass-sim0 bus 0 target 0 lun 0
   kernel: da0: <  > Fixed Direct Access SCSI-2 device
   kernel: da0: 40.000MB/s transfers
   kernel: da0: 55796MB (114270345 512 byte sectors: 255H 63S/T 7113C)

Full dmesg is attached.

-- 
DE