Become a MacRumors Supporter for $25/year with no ads, private forums, and more!


macrumors newbie
Original poster
May 30, 2008

I searched the internet high and far and have found many formatting issue posts all around but none that covers this particular error.

I have a USB Stick with the following specs according to Disk Utility:
Name : Udisk Udisk 2.0 Media
Type : Disk

Partition Map Scheme : Unformatted
Disk Identifier : disk1
Media Name : Udisk Udisk 2.0 Media
Media Type : Generic
Connection Bus : USB
USB Serial Number : 0001CFCFCFC5DB1C
Device Tree : IODeviceTree:/PCI0/EHC1@1D,7
Writable : Yes
Ejectable : Yes
Location : External
Total Capacity : 2.07 GB (2,066,743,296 Bytes)
Disk Number : 1
Partition Number : 0
S.M.A.R.T. Status : Not Supported

I can format the stick just fine in Windows but every time I try to erase the Stick or use the partition menu in Disk Utility it starts trying to "Unmount" the device until it times out with the following error:

2011-08-29 19:39:26 +0200: Preparing to erase : “Untitled”
2011-08-29 19:39:26 +0200: Partition Scheme: GUID Partition Table
2011-08-29 19:39:26 +0200: 1 volume will be created
2011-08-29 19:39:26 +0200: Name : “Untitled”
2011-08-29 19:39:26 +0200: Size : 2.07 GB
2011-08-29 19:39:26 +0200: File system : Mac OS Extended (Journaled)
2011-08-29 19:39:26 +0200: Unmounting disk
2011-08-29 19:42:01 +0200: Disk Erase failed with the error:

Wiping volume data to prevent future accidental probing failed.
2011-08-29 19:42:01 +0200: Erase complete.
2011-08-29 19:42:01 +0200:

After that the stick becomes unreadable and when plugged in again you get prompted that the stick cannot be read and OSX gives you the option to "Initialize..." which ends in Disk Utility again getting stuck on the "Unmounting" of the device.

I even tried from the terminal with "diskutil partitiondisk disk1 JHFS+ newdisk 100%" without success, aside from the fact that I was able to get this error number:
"Error: -69825: Wiping volume data to prevent future accidental probing failed"

On top of the USB Stick listing in Disk Utility, it also lists a greyed out CDROM Icon Entry for the stick "Udisk Udisk 2.0 Media", can't do anything with that.

I tried formatting this stick in all ways I can think of on a MAC under OSX and it just does not work.


Thanks for any input!



macrumors newbie
Oct 25, 2011
It's a Lion problem

I had to fix it on my Snow Leopard system.:mad: If you find a Lion fix, please post it.


macrumors 603
Aug 6, 2007
Can you "remove all formatting" in windows and then try again as new in Lion?


macrumors newbie
Jan 19, 2009
Boston, MA
Yeah, the UDisk is a SanDisk drive partition for there software suite that comes with there USB drives.

You have to use a Windows (XP or greater) computer and run the UDisk software. If you go to the settings or tools portion there is a removal tool that will let you remove that partition.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.