6 Replies Latest reply: Nov 10, 2012 10:07 AM by Kappy
a.z.p. Level 1 (10 points)



I recently bought an 8GB USB stick. Once I was running a program off of the flash drive on a windows computer and I did not eject it properly. Now when I connect the drive to a windows computer, and try to format it, it says the drive is write protected. The disk seems to be formatted as RAW. The disk used to be formatted as FAT 32 as I was also using it for tranfering files between windows and Mac computers. When I connect to a Mac now, the disk is not recognized by Finder and only in Disk Utility. When I verify it:


Disk Util.png

It says:


Verifying volume “disk3s1”

** /dev/disk3s1

Invalid BS_jmpBoot in boot block: 000000

Error: This disk needs to be repaired. Click Repair Disk.


but I can't repair or erase the disk. I don't care about the data on the drive, I just want it to work again. I will spend time on it and go for any method if you know of one. Any help would be greatly appreciated!

iMac, Mac OS X (10.6.8)
  • Allan Eckert Level 9 (50,709 points)

    Try to repartition the flash drive to MS-DOS with Disk Utility and see what that does for you.



  • Kappy Level 10 (265,914 points)

    Why can't you repair it?


    Drive Preparation


    1. Open Disk Utility in your Utilities folder.


    2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.


    3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed.


    4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.


    5. Set the format type to Mac OS Extended (Journaled.) Click on the Security button, check the button for Zero Data and click on OK to return to the Erase window.


    6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.


    Steps 4-6 are optional but should be used on a drive that has never been formatted before, if the format type is not Mac OS Extended, if the partition scheme has been changed, or if a different operating system (not OS X) has been installed on the drive.

  • a.z.p. Level 1 (10 points)

    Nothing is clickable, it says the partion cannot be modified:



  • Kappy Level 10 (265,914 points)

    What happens if you select the grayed out entry labeled disk3s1, then click on the Mount icon in the toolbar? Then you may be able to just erase the disk.

  • a.z.p. Level 1 (10 points)

    It was unable to be mounted.

  • Kappy Level 10 (265,914 points)

    Do you happen to have a read-only switch on the flash drive?