External hard drive turned itself read-only...

I run a Samsung NC10 with Ubuntu Netbook remix.

Yesterday I noticed that my external hard drive (a 500GB Transcend) was running very tight on space. I used the BAOBAB disk usage analyser and deleted about 150GB of old backups. When trying to then create a new folder in which to put a shiny new backup, I noticed that I couldn't do so. In fact, I couldn't do anything with it that involved writing to the hard drive.

After a short bit of googling I reckoned I should run a chown command to change ownership of the drive to me by force. That didn't work. I then used chown -R to ensure that all files would also change. Still didn't work.

I am completely and utterly stumped - how in the world could the drive suddenly become read-only?

Any pointers would be appreciated...

 

Could you post the output of this command:

Code:

mount

Could you try creating an empty file as root user in the root of your mount point i.e. something like:

Code:

sudo touch /mnt/mydisk/myfile

Replace /mnt/mydisk with the mount point.

I'm sure you cannot delete files if the drive were mounted read-only.

Also is it by any chance an NTFS file system ? chown will work only on *nix based file systems.

 

Look at your permissions of the folder in question with the -l flag:

Code:

ls -l /media/blah

If you aren't the owner or don't have write permission then you need to chown it again or chmod it so that you can write.

You can also make sure it didn't get mounted read-only somehow. Look at the output of:

Code:

cat /proc/mounts

If it's ntfs you may be missing some steps (see the manpage for ntfs-3g).

 

Thanks for the replies. Happily, problem is solved.

A friend suggested that there might be some corruption in the drive. I hooked it up to a Windows PC (Vista) and ran the standard error checking tool on the drive. It completed after about 2 hours and, sure enough, it reported a good deal of errors. After using the tool to repair the errors the drive was immediately usable again.

 

Linux has some command-line utilities for NTFS volumes. Next time, you can try ntfsck, if you have ntfs-progs installed.

 

Although ntfsck of ntfsprogs was active for some time, it has been inactive for a very long time (I guess from 2004) and usually it is always suggested to use M$ WIN based programs to check and fix errors for NTFS volumes. In fact mounting of ntfs volumes fail during bootup or on-demand when it detects problems with the NTFS's-superblock-equivalent and it prints an error and suggest to run Windows based programs to fix the error and remount.