wheretofindmatt

Q: How to Force Format USB drive? (Permissions lost)

Hi all,

 

Normally I would just buy a new one - but I am stuck at sea for 2 months! 

 

  • I have a 32GB San disk USB Cruze (USB Stick)
  • I have owned it from new and used it on the same computer.  For some reason I have lost permissions for it.  I can read, but that is all.
  • I wish to either regain ownership of the USB stick and therefore have full permissions or I don't mind formatting and starting from scratch.

 

A long time has been spent on this, with no light seen at the end of the tunnel..!

 

  • In DiskUtility as I have no persmissions I cannot do anything (First Aid or Restore) except view the USB stick
  • In Terminal I keep coming accross "Permission denied".  The route of the USB is; /dev/disk0s2

 

Can I force a format or anything?  I am not a computer wizard, so any terminal commands to help, please include what I need, I sometimes get lost when people say <something> <something> i'm not always sure what they are refering to..

 

I look forward to seeing if there is a solution, it would really save me with regards to my studies whilst i'm at sea.

 

If there is a program (a small one) I maybe able to download it, if there's one to brute force a format.. 

 

Hope someone can help.. 

 

Thanks Matt

MacBook Pro (Retina, Mid 2012), iOS 6.0.1

Posted on Sep 10, 2013 5:35 AM

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Q: How to Force Format USB drive? (Permissions lost)

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  • by Frank Caggiano,

    Frank Caggiano Frank Caggiano Sep 10, 2013 7:04 AM in response to wheretofindmatt
    Level 7 (25,796 points)
    Sep 10, 2013 7:04 AM in response to wheretofindmatt

    If you're logged in in an admin account permissions should not be an issue.

     

    So are you logged in as an admin?

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 8:18 AM in response to Frank Caggiano
    Level 1 (6 points)
    Sep 10, 2013 8:18 AM in response to Frank Caggiano

    Hi Frank,

     

    I am admin on my computer, there are no other accounts...

  • by Frank Caggiano,

    Frank Caggiano Frank Caggiano Sep 10, 2013 8:24 AM in response to wheretofindmatt
    Level 7 (25,796 points)
    Sep 10, 2013 8:24 AM in response to wheretofindmatt

    If you do a Get Info on the drive from finder is the drive locked?

     

    Never seen Disk Utility refuse an Admin access to a drive

     

    In DiskUtility as I have no persmissions I cannot do anything (First Aid or Restore) except view the USB stick

    What to you mean by view the USB stick in this context?

     

    Some USB sticks come  with software installed that will give this behavior but you say you have been able to read and write this specific USB stick in the past. Has anything changed on your system or the stick?

  • by John_ J,

    John_ J John_ J Sep 10, 2013 8:33 AM in response to wheretofindmatt
    Level 1 (70 points)
    Sep 10, 2013 8:33 AM in response to wheretofindmatt

    You should be able to change the permissions of the flash dirve without having to erase all the data on it by reformating.

     

    Check the current owner/group settings of the flash drive (make sure it's plugged in). The following code will show which volumes are on the system and some details about those volumes:

        

         In Terminal:

              enter "cd /Volumes"

              enter "ls -l"

    Screen Shot 2013-09-10 at 8.30.12 AM.png

    In my example, the "NO NAME" drive is a usb drive connected to my computer. Note the two names associated with the usb volume (mine are "johnjaques" and "staff"), whate are yours?

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 8:35 AM in response to Frank Caggiano
    Level 1 (6 points)
    Sep 10, 2013 8:35 AM in response to Frank Caggiano

    I can view it in the left hand panel along with my hard disk.  All other options are greyed out.

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 8:39 AM in response to John_ J
    Level 1 (6 points)
    Sep 10, 2013 8:39 AM in response to John_ J

    total 40

    drwxrwxrwx@ 1 Matt  staff  16384  1 Jan  1980 32GB USB

    lrwxr-xr-x  1 root  admin      1  5 Sep 20:42 Matt -> /

    drwxrwxrwx  0 root  wheel      0 10 Sep 20:57 MobileBackups

     

    No idea what staff is but here are mine..

  • by Linc Davis,

    Linc Davis Linc Davis Sep 10, 2013 8:53 AM in response to wheretofindmatt
    Level 10 (207,983 points)
    Applications
    Sep 10, 2013 8:53 AM in response to wheretofindmatt

    Some flash drives have a failure mode in which they are irreversibly write-locked by the internal controller when it detects a write error. If you can't erase the drive in Disk Utility, that's almost certainly what has happened. To be sure, test it with another computer, if possible.

  • by John_ J,

    John_ J John_ J Sep 10, 2013 9:12 AM in response to wheretofindmatt
    Level 1 (70 points)
    Sep 10, 2013 9:12 AM in response to wheretofindmatt

    As mentioned earlier, the first name in the series is the Owner and the second is the Group for the volume. I wanted to make sure you were the owner in this case, you are.

     

    You can use the diskutil tool in Terminal to re-format the Volume if you'd like, just know it will erase all the data off the USB drive.

        

         In Terminal (type):

              "diskutil reformat 32GB\ USB"

     

     

    In addition, for a complete listing of diskutil options type "man diskutil" in Terminal (space bar to show more, q to exit).

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 9:13 AM in response to Linc Davis
    Level 1 (6 points)
    Sep 10, 2013 9:13 AM in response to Linc Davis

    Linc, not the answer I was looking for!!

    The work PC wont format it or write to it either (it's in FAT32).  If that is the case, then it's a bit silly..

     

    I'm sure there's some wizardry someone can give me!  Or i'll live in hope (for 2 months any way!)

     

    Linc Davis wrote:

     

    "Some flash drives have a failure mode in which they are irreversibly write-locked by the internal controller when it detects a write error. "

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 9:16 AM in response to John_ J
    Level 1 (6 points)
    Sep 10, 2013 9:16 AM in response to John_ J

    Hi John,

    Thanks for your help - you knew it wasn't going to be that easy!

     

    Matts-MacBook-Pro-2:volumes Matt$ diskutil reformat 32GB\ USB

    Started erase on disk1s1 32GB USB

    Unmounting disk

    Error: -69874: Couldn't modify partition map

     

    And data is still on the disk..

  • by John_ J,

    John_ J John_ J Sep 10, 2013 9:23 AM in response to wheretofindmatt
    Level 1 (70 points)
    Sep 10, 2013 9:23 AM in response to wheretofindmatt

    Do you need the partion type to be FAT32? If not, it can be re-partioned using diskutil as well...

  • by Linc Davis,

    Linc Davis Linc Davis Sep 10, 2013 9:41 AM in response to wheretofindmatt
    Level 10 (207,983 points)
    Applications
    Sep 10, 2013 9:41 AM in response to wheretofindmatt

    I'm sure there's some wizardry someone can give me!

     

    Only someone who knows how to fix a failed flash drive.

  • by wheretofindmatt,

    wheretofindmatt wheretofindmatt Sep 10, 2013 9:41 AM in response to John_ J
    Level 1 (6 points)
    Sep 10, 2013 9:41 AM in response to John_ J

    Not this USB stick, all those puppies are greyed out and not an option in the partition tab

  • by John_ J,

    John_ J John_ J Sep 10, 2013 9:47 AM in response to wheretofindmatt
    Level 1 (70 points)
    Sep 10, 2013 9:47 AM in response to wheretofindmatt

    Something else to try... Lets try reparing the partion map.

     

         In Terminal (type):

              "diskutil repairDisk 32GB\ USB"

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