Trying to repair an external storage device in Disk Utility I first clicked "Verify Disk..." and then "Repair Disk..." but i got the below error:

Verify and Repair volume “disk3s2”
Repairing file system.
** /dev/rdisk3s2
Invalid BS_jmpBoot in boot block: cc4542
File system check exit code is 8.
Updating boot support partitions for the volume as required.
Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.

How do I solve the problem?

Specs: OS X Yosemite 10.10.5

  • Please add the output of sudo gpt -r show disk3 (or the respective disk identifier of the external drive) entered in Terminal.app to your question by editing it in!
    – klanomath
    Commented Aug 31, 2016 at 10:44

1 Answer 1


You could easily wipe the drive and start fresh - use care that disk 3 is really the disk you wish to erase everything.

diskutil eraseDisk JHFS+ UntitledUFS disk3

If that fails, you likely have a hardware error (unless the failure is your OS or not using an account with sudo permissions). If that succeeds, you could then use Disk Utility to rename things as you please or learn more about diskutil and use it to rename / repartition / reformat the drive going forward.

  • 1
    Reading the question I'd assume that the disk/volume holds some data/content and the OP has no backup. This is no good advice without mentioning that the data is gone after executing the above command.
    – klanomath
    Commented Aug 31, 2016 at 12:16
  • it was a bootable drive ,,previously ..., i dont want the data in the drive ..and what is this line of error ......>>>---- Invalid BS_jmpBoot in boot block: cc4542
    – KUSHA B K
    Commented Aug 31, 2016 at 12:52

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