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How to format a USB stick (not what you think)

mac-collector

mac-collector

macrumors regular
Original poster
Apr 8, 2012
117
0
Europe
Hello.

I have a USB stick. It seems to be partitioned into two. One of which I can read, write and format at will, the other one is read only. It doesn't show up in disk utility but always mounts when I plug it in. When I try to erase it in the terminal I get "Error: -69877: Couldn't open device". It is under the CD Partition Scheme. Any ideas on how I can format the whole thing?

Thanks.
 
Is it a normal USB flash memory thumb drive or did it come with some computer/device as install medium?
Do you have access to Windows (Boot Camp, VM or other Windows PC), where you could try Disk Management?
 
It came with some hardware and it has some applications for it. I have already installed them and copied them for later. I have tried Disk management, but the format option was greyed out.
 
You need to repartition it. In disk utility click on the hardware device ("x GB pen drive flash memory whatever") on the left side and then select "Partition" in the right pane. Select "1 partition" instead of "Current" from the "Partition layout" dropdown, click "apply", done - an USB stick with a single x GB partition.
 
"I have a USB stick. It seems to be partitioned into two. One of which I can read, write and format at will, the other one is read only. It doesn't show up in disk utility but always mounts when I plug it in. When I try to erase it in the terminal I get "Error: -69877: Couldn't open device". It is under the CD Partition Scheme. Any ideas on how I can format the whole thing?"

It sounds like you have a flashdrive with "U3" software/protection installed on it. U3 "exists" on a separate partition and does such things as provide password protection to the drive, etc. You CANNOT remove it with Disk Utility on the Mac, it is resistant to that. (Note: there may be other forms of such protection named other than "U3", but that's what I've seen here in the USA).

I have a Sansa flashdrive that came with this.

The only way I know to get rid of it is to take the flashdrive in question to a PC running Windows, and examine it carefully. You may find some "utilities" on it that will permit you to disable and remove the U3 partition. Once this is done, you can take the flashdrive back to the Mac, and then use Disk Utility to do a complete re-initialization, after which the (old) U3 partition/software will be gone.

Without a PC, I don't believe there's any way to get rid of this protection "on the Mac side"....
 
mac-collector said:
Please read the OP. It does not show up in disk utility. It is one physical disk, but shows up as two. I uploaded an attachment so you can see what I mean.

It's the 'CD' disk which is the other half.
Click to expand...

Regardless, hwojtek's solution might work. It's a hidden partition, but it's a partition all the same. Erasing the partition you can see wouldn't work, but repartitioning the drive as he suggested would.

If that doesn't work, you can try Gparted, a Linux-based tool for partitioning that likely will be able to see the hidden partition without issue.

jW
 
When I say it doesn't show up in disk utility, then it does not show up in disk utility. (Given I haven't tried all 'hacks' or debug options, but all the obvious 1-click options I have tried)

I have been reading about the U3 partitions and even downloaded the official U3 uninstaller, but it didn't recognise the disk.
I will give Gparted a try.

So to recap: There is a way to write-protect your disk in such a way that no mac can ever erase it?
 
mac-collector said:
When I say it doesn't show up in disk utility, then it does not show up in disk utility. (Given I haven't tried all 'hacks' or debug options, but all the obvious 1-click options I have tried)

I have been reading about the U3 partitions and even downloaded the official U3 uninstaller, but it didn't recognise the disk.
I will give Gparted a try.

So to recap: There is a way to write-protect your disk in such a way that no mac can ever erase it?
Click to expand...

I didn't say you were wrong about it not showing up. I'm saying it doesn't matter. You can see the drive itself, regardless of whether the partition shows up. Did you even try what was suggested?

It's not a U3 partition, so I'm not sure why you tried that. It's similar, but the tools would not be the same.

And yes, there are read-only flash drives. They could have included a small portion of the drive that is physically read-only after the initial setup, and no computer anywhere could ever erase it. Chances are they didn't bother to go to those lengths, however.

jW
 
Mal said:
I didn't say you were wrong about it not showing up. I'm saying it doesn't matter. You can see the drive itself, regardless of whether the partition shows up. Did you even try what was suggested?

It's not a U3 partition, so I'm not sure why you tried that. It's similar, but the tools would not be the same.

jW
Click to expand...

I can only see the part of the drive that is read & write. And how can you be so sure it's not a U3 partition?
 
mac-collector said:
I can only see the part of the drive that is read & write. And how can you be so sure it's not a U3 partition?
Click to expand...

Because U3 is a propriety system, and it would be called a U3 Partition if it was. Like I said, it's similar, but not the same.

Look, either try what you were told should be done, or don't. If you don't try, then you'll never know if it would have worked. If you don't try it, I won't respond any more to you.

jW
 
iisforiphone said:
my WD External also has some silly backup software or something that mounts everytime i attach it to my MBP, not crucial to get rid of it but still dont like
Click to expand...

Why do the companies do this? It's horribly annoying. What I also dislike about mine is that it opens a separate-autoplay window in Windows every time you connect it.
 
mac-collector said:
Why do the companies do this? It's horribly annoying. What I also dislike about mine is that it opens a separate-autoplay window in Windows every time you connect it.
Click to expand...

ya its annoying when i eject the drive and that stupid WD Smartware stays on my screen than i have to reconnect the harddrive and remember to eject the Smartware software first
 
Mal said:
Look, either try what you were told should be done, or don't. If you don't try, then you'll never know if it would have worked. If you don't try it, I won't respond any more to you.

jW
Click to expand...

I tried and it didn't work, so I don't know why you recommended that. It only erased the writeable part again. I haven't tried Gparted because I don't have a linux system I can use at the moment.
 
mac-collector said:
I tried and it didn't work, so I don't know why you recommended that. It only erased the writeable part again. I haven't tried Gparted because I don't have a linux system I can use at the moment.
Click to expand...

Not so hard, right? I couldn't know whether it would work on that particular flash drive or not, but until you tried it, no one did.

As for Gparted, you don't need a Linux system. You create a bootable DVD and use that. I've used it on my MacBook Pro several times, and I've never had Linux installed. Here's the link: http://gparted.sourceforge.net/livecd.php

jW
 
Mal said:
Not so hard, right? I couldn't know whether it would work on that particular flash drive or not, but until you tried it, no one did.

jW
Click to expand...

Just like I couldn't know that all U3 partitions were actually called U3.
I only have access to a MBA at the moment, so the bootable disk will have to wait.
 
Again -- as I mentioned in my post above -- the fast easy way is to take the flashdrive to a _Windows_ machine, mount it, examine it carefully, and locate the software (probably on the protected partition that will mount on the PC side) that will disable and remove the protected partition...
 
Fishrrman said:
Again -- as I mentioned in my post above -- the fast easy way is to take the flashdrive to a _Windows_ machine, mount it, examine it carefully, and locate the software (probably on the protected partition that will mount on the PC side) that will disable and remove the protected partition...
Click to expand...

I tried that, but there is no software to disable it. I found the VID and now know that Logitech made the drive. Does anyone know if Logitech makes any software to manage their flash drives?
 
balamw said:
...a VM on your Mac...
Click to expand...

I tried XP in virtualbox but the disk won't mount! And that guy is right, I tried 64-bit Windows 7 and that doesn't work.

Maybe I should keep removing it from my mac without ejecting, hoping it will get corrupted. Or invest in a very strong magnet......
 
mac-collector said:
I tried XP in virtualbox but the disk won't mount! And that guy is right, I tried 64-bit Windows 7 and that doesn't work.

Maybe I should keep removing it from my mac without ejecting, hoping it will get corrupted. Or invest in a very strong magnet......
Click to expand...

Magnets don't work with USB flash memory thumb drives.

Btw, why go through all that trouble, when you can get 4 GB USB flash memory thumb drives for 10 € and less?
 
simsaladimbamba said:
Magnets don't work with USB flash memory thumb drives.

Btw, why go through all that trouble, when you can get 4 GB USB flash memory thumb drives for 10 € and less?
Click to expand...

You have some serious trouble understanding my sarcasm......
Maybe it's a 128 GB drive? No, but you shouldn't throw it away just 'cause you can't fix it.
 
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