4:51 - Thursday, 24 April 2014

Why Is My USB Drive Read Only On Ubuntu Only?

I formatted a USB flash drive as FAT in Ubuntu, copied some files, made it bootable, and now it only mounts as read-only.

If I stick the same drive in Windows or Mac, it is writable, so it’s not the hardware switch on the drive itself.

  • How do I make this permanently mount as writable.
  • What could have caused this bizarre behavior (so it doesn’t happen again)?

No idea what was the cause. Reformatted (from Linux) and all works well now.

Double check the file system on the device (preferably chkdsk in Windows, or dosfschk under *nix). It would also help to see the output of #mount so we can see how the filesystem is mounted. You could also try this:

sudo umount /path/to/devicesudo mount -t  -w /path/to/device /mount/path

dosfsck command helped me to resolve the issue.

I tried the following:

$ sudo dosfsck -r /dev/sdb1dosfsck 3.0.12, 29 Oct 2011, FAT32, LFNThere are differences between boot sector and its backup.Differences: (offset:original/backup)  71:4a/4e, 72:52/4f, 73:41/20, 74:4d/4e, 76:4e/4d, 77:20/451) Copy original to backup2) Copy backup to original3) No action? 1Perform changes ? (y/n) y/dev/sdb1: 3435 files, 1472986/1956337 clusters

i.e. Copying the original boot sector to backup resolved the issue.