Problem with USB mass storage

[datastream]

hi,
    my usb hdd does not work.it seems broken again.


#uname -a
FreeBSD datastream-laptop.people.163.org 9.0-CURRENT FreeBSD 9.0-CURRENT
#5 r196859: Sat Sep  5 21:27:55 CST 2009    
root at datastream-laptop.people.163.org:/usr/obj/usr/home/datastream/freebsd/sys/G8laptop 
amd64


usbd_set_config_index:523: could not read device status: USB_ERR_SHORT_XFER
ugen6.2: <JMicron> at usbus6
umass0: <MSC Bulk-Only Transfer> on usbus6
umass0:  SCSI over Bulk-Only; quirks = 0x0000
umass0:2:0:-1: Attached to scbus2
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <Maxtor 7 Y250M0 11W0> Fixed Direct Access SCSI-2 device
da0: 40.000MB/s transfers
da0: 238475MB (488397168 512 byte sectors: 255H 63S/T 30401C)
ugen6.2: <JMicron> at usbus6 (disconnected)
umass0: at uhub6, port 2, addr 2 (disconnected)
(da0:umass-sim0:0:0:0): Synchronize cache failed, status == 0x3f, scsi
status == 0x0
(da0:umass-sim0:0:0:0): lost device
(da0:umass-sim0:0:0:0): removing device entry



Thanks,
Kevin