Auto-mounted USB thumb drive only has user write permission if FAT16 or FAT32
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Ubuntu |
Invalid
|
Undecided
|
Unassigned |
Bug Description
If I prepare a USB thumb drive (memory stick) with either FAT16 or FAT32 file systems, it will auto-mount and user write access is granted (i.e. user can drag from Home folder to USB drive folder to write to the device).
However, if I prepare the same thumb drive with an ext3 file system, the device will still auto-mount correctly, but user write access is denied.
I have demonstrated this on two different USB memory devices (old Memorex 128M Thumb Drive and a 5GB Pleomax Drive).
I used gparted to partition and format the devices.
Feisty Fawn Ubuntu 7.04 completely up to date as of 06/23/07
I followed many web search threads about people having trouble getting user write access to USB devices, but I haven't seen it trouble shot to this specific observation. I was originally trying to get user write access on my Pleomax re-formated to ext3 and notice that my Memorex was formated as FAT16 and worked just fine. So, I played around re-formating both devices to find this.
This is likely to be a permission problem. Many filesystems commonly used on flash drives (like vfat) do not have support for file permission/ ownership themselves. On modern distributions like Ubuntu, fake permissions are put on top of these filesystems in such a way that normal users have read and write permissions.
Ext3 on the other hand does have full support for unix style file permissions (usb drive or not), and these will be respected by the operating system. As a result you may well have insufficient rights by default to write to the filesystem as a normal user after formatting. Please mount the usb drive and then change the permissions and/or ownership in order to make the drive writable (using sudo when needed).