linux下使用U盘时的文体

待挂载设备是一个mp4,
使用 mount -t vfat /dev/sda1 /mnt/usb  (usb目录已经建好) 后
出现下列提示:
usb-uhci.c :interrupt , status 3, frame# 1393
usb-uhci.c :interrupt , status 3, frame# 1261
usb-uhci.c :interrupt , status 3, frame# 1128
usb-uhci.c :interrupt , status 3, frame# 995
usb-uhci.c :interrupt , status 3, frame# 863
SCSI device sda: 477952 512-byte hdwr sector (245M)
sda:  Write Protect is off
   I/O error: dev 08:00, sector 0
   unable to read partition table
mount: /dev/sda1 is not  a valid block device


使用 fdisk -l /dev/sda出现下列提示:
usb-uhci.c :interrupt , status 3, frame# 1393
usb-uhci.c :interrupt , status 3, frame# 1261
usb-uhci.c :interrupt , status 3, frame# 1128
usb-uhci.c :interrupt , status 3, frame# 995
usb-uhci.c :interrupt , status 3, frame# 863
SCSI device sda: 477952 512-byte hdwr sector (245M)
sda:  Write Protect is off
   I/O error: dev 08:00, sector 0
   unable to read partition table
usb-uhci.c :interrupt , status 3, frame# 762
usb-uhci.c :interrupt , status 3, frame# 627
usb-uhci.c :interrupt , status 3, frame# 494
usb-uhci.c :interrupt , status 3, frame# 361
usb-uhci.c :interrupt , status 3, frame# 228
SCSI device sda: 477952 512-byte hdwr sector (245M)
sda:  Write Protect is off
   I/O error: dev 08:00, sector 0
   unable to read partition table

请问为什么?　　　　　　

问题不少……
不过先试试 /dev/sda吧 　　　　　　

重新进行了一遍操作:
第一步,接上MP4:
系统提示下列信息:
usb.c: USB device 2 (vend/prod 0xea0/0x6803) is not claimed by any active
driver.
  Vendor: IPED      Model: MP4               Rev: 1.00
  Type:   Direct-Access                      ANSI SCSI revision: 02

第二步:
fdisk -l /dev/sda
系统提示:
Attached scsi removable disk sda at scsi1, channel 0, id 0, lun 0
SCSI device sda: 477952 512-byte hdwr sectors (245 MB)
sda: Write Protect is off
usb-uhci.c: interrupt, status 3, frame# 1250
usb-uhci.c: interrupt, status 3, frame# 1122
usb-uhci.c: interrupt, status 3, frame# 989
usb-uhci.c: interrupt, status 3, frame# 856
usb-uhci.c: interrupt, status 3, frame# 723
SCSI device sda: 477952 512-byte hdwr sectors (245 MB)
sda: Write Protect is off
I/O error: dev 08:00, sector 0
unable to read partition table
usb-uhci.c: interrupt, status 3, frame# 617
usb-uhci.c: interrupt, status 3, frame# 487
usb-uhci.c: interrupt, status 3, frame# 354
usb-uhci.c: interrupt, status 3, frame# 221
usb-uhci.c: interrupt, status 3, frame# 88
SCSI device sda: 477952 512-byte hdwr sectors (245 MB)
sda: Write Protect is off
I/O error: dev 08:00, sector 0
unable to read partition table
I/O error: dev 08:00, sector 0

第三步:mount -t vfat /dev/sda /mnt/usb
系统提示:
usb-uhci.c: interrupt, status 3, frame# 1716
usb-uhci.c: interrupt, status 3, frame# 1586
usb-uhci.c: interrupt, status 3, frame# 1453
usb-uhci.c: interrupt, status 3, frame# 1320
usb-uhci.c: interrupt, status 3, frame# 1187
SCSI device sda: 477952 512-byte hdwr sectors (245 MB)
sda: Write Protect is off
I/O error: dev 08:00, sector 0
unable to read partition table
usb-uhci.c: interrupt, status 3, frame# 1083
usb-uhci.c: interrupt, status 3, frame# 951
usb-uhci.c: interrupt, status 3, frame# 818
usb-uhci.c: interrupt, status 3, frame# 685
usb-uhci.c: interrupt, status 3, frame# 552
Device busy for revalidation (usage=1)
I/O error: dev 08:00, sector 0
FAT: unable to read boot sector
mount: wrong fs type, bad option, bad superblock on /dev/sda,
       or too many mounted file systems
usb-uhci.c: interrupt, status 3, frame# 433
usb-uhci.c: interrupt, status 3, frame# 297
usb-uhci.c: interrupt, status 3, frame# 164
usb-uhci.c: interrupt, status 3, frame# 31
usb-uhci.c: interrupt, status 3, frame# 1946
SCSI device sda: 477952 512-byte hdwr sectors (245 MB)
sda: Write Protect is off
I/O error: dev 08:00, sector 0
unable to read partition table

晕了,真得觉得菜鸟太惨了.......................　　　　　　

各位高手，知道的话说一声啊！！！！