In OS X, USB Drive also mounting non-existent CD-R

December 20, 2006 12:16 PM

In OS X, when I mount this new USB drive, a dialog appears with "You inserted a blank CD...." How do I get this to stop showing up? Also, what Volume Format should I use to allow the USB drive to be mounted on both OS X and Windows?

The full text of the dialog that appears is "You inserted a blank CD. Chose an action from the pop-up menu or click Ignore." If I click OK or Ignore, the USB drive is mounted (Called "483.8 MB Relay UFD Media" in Disk Utility) AND a CD-R image is also mounted (Called "Relay UFD Media".) I've already reformated the USB drive as "Mac OS Extended (Journaled)"

posted by gwint to computers & internet (12 comments total)

I'm not sure about it showing up as a CD, but to get it to mount on a Mac, as well as windows, use FAT32. Mac can read windows, but windows can't read mac, so use FAT32.
posted by drleary at 12:22 PM on December 20, 2006

Format options are:
* Mac OS Extended (Journaled)
* Mac OS Extended
* Mac OS Extended (Case-sensitive, Journaled)
* Mac OS Extended (Case-sensitive)
* Mac OS Standard
* MS-DOS File System
* UNIX File System

I assume "MS-DOS File System" is FAT32, but would that restrict me to 8.3 filenames?
posted by gwint at 12:29 PM on December 20, 2006

There are some newer USB flash drives that pretend to be a CD in order to get Windows to auto-play some utilities on them. I think they're referred to by the brand name U3, or something like that. This is probably why it's being misidentified.

If you reformat it completely, destroying the fake filesystem, it ought to fix the issue, although you'll lose any information on the drive and the auto-play functionality in Windows.
posted by odinsdream at 12:36 PM on December 20, 2006 [1 favorite has favorites]

FAT16 has the filename limitations, you should be fine with FAT32.
posted by odinsdream at 12:38 PM on December 20, 2006

Yes, use MS-DOS file system. I'm *almost* certain that it won't restrict you to 8.3, but my windows machine is dead right now, so I can't test it.
posted by drleary at 12:39 PM on December 20, 2006

Sorry for the multiple comments. You might need to repartition the drive, too. You can do it in Disk Utility on the Mac, or Disk Management on Windows. You'll probably find a small partition where the fake CD filesystem resides, and another larger filesystem where the actual data on the disk is intended to go. Delete both, then recreate one partition that fills the whole disk. Then format that partition as FAT32.
posted by odinsdream at 12:40 PM on December 20, 2006

Mac OS X definitely supports long filenames on FAT32 volumes. However, do bear in mind that you can run into troubles with some characters Mac OS X allows; for example, the Mac will let you use a backslash in filenames and these files can be copied to a FAT32 disk, but since the backslash can be used as a directory separator on Windows (though Windows does now support forward slashes), the character doesn't actually appear when you mount the volume on Windows. (Oddly, it's still there when you mount the volume on the Mac.) The backslash isn't the only reserved character, either, but it's the first one that occurred to me.

Apparently, some of the limitations on characters are in the filesystem itself, and some are in Windows Explorer or other applications that deal with filenames or paths. It's hard to disentangle these. I did notice that Windows Explorer won't let you give a file a name with a backslash in it, even on an NTFS volume, where it should, if I'm reading things right, be legal.

This probably will not have much of an effect on your use, but I can imagine situations where it might come into play.
posted by kindall at 1:05 PM on December 20, 2006

Windows file naming rules are here.
posted by flabdablet at 1:30 PM on December 20, 2006

I've reformated and repartitioned on the Mac and still no luck with the CD dialog. On Windows, partition options appear to be greyed out. I'm at a loss.
posted by gwint at 1:48 PM on December 20, 2006

Here's what I see in Disc Management on Windows:
all volumes
options for fake CD volume
options for usb volume
posted by gwint at 2:07 PM on December 20, 2006

Here's something from google that might be useful:

How to remove U3 from a USB drive.
posted by odinsdream at 2:33 PM on December 20, 2006

Thanks for the followup odinsdream. Going to the u3.com link provided in that blog post, you first need to answer why you would like to remove this "feature." One option is "Because I run OS X or Linux." Then you're sent to the uninstaller download page-- which is Windows only... luckily I've got an XP box I keep around just to uninstall annoying software from the usb drives, but non-Windows users would be SOL.

Anyway, many thanks-- problem solved!
posted by gwint at 2:53 PM on December 20, 2006 [1 favorite has favorites]