Privileges for removable disks
Privileges for files and folders on removable media indicate the user "unknown" with a user identification number (UID) of 99. The result of this is that the files and folders act as if owned by whichever user is currently logged in to Mac OS X. However, privilege changes (if any) made by the logged-in user do not persist when that user logs out. When a subsequent user logs in to the computer, the removable disk acts as if owned by the subsequent user.
This behavior preserves the portability of removable disks, the trait for which they are often employed. Superficially, the media behaves as it would if used in Mac OS 9.
Changing privileges behavior
Warning: If you are using Mac OS X Server version 10.0.3 or 10.0.4 and wish to use external FireWire drives for storage, you must update to Mac OS X Server 10.1 to use the steps presented below. Use of removable media for a server is not tested or qualified by Apple, and you should consult the support resources provided by the vendor of your removable media regarding its worthiness for use as a server storage device.
If you wish to share a FireWire hard disk or other appropriate removable media with Mac OS X Server, follow these steps to allow privileges to behave as an internally-installed disk:
1. Select the disk in the Finder.
2. Choose Show Info from the File menu.
3. Choose Privileges from the pop-up menu in the Info window.
4. Click the checkbox to deselect "Ignore privileges on this volume."
5. Close the Info window.
Once this is done, permission changes are preserved on the volume.