Always getting bad magic number in super-block
 

I've been setting up a number of netbooks for friends in a group I belong to. I recommended and I am installing Ubuntu 10.04 and/or Linux Mint 9 on all of the netbooks. The netbooks are all identical. Everything has seemed OK until yesterday. I tried to set the label on the new disk using: # e2label /dev/sda newlabel

The error is Bad magic number in super-block while trying to open /dev/sda. Couldn't find valid filesystem superblock.

But the filesystem seems fine. It is mounted. It booted up without errors. But all the e2* tools give the same error.

So I checked another netbook with an identical fresh install of Ubuntu 10.04 32-bit. It gives the same error although the system appears to work fine.

Next I went and checked my own netbook. It is identical except I swapped out the HDD for an OCZ Vertex SSD. I aligned the partitions and prepared that drive carefully. It seems to work great. But when I ran e2label on it I got the same error message.

All the other installs are fresh, clean, standard installs where I let the installer use the whole disk and do the partitioning automatically. All are using ext4. I did a fresh install of Linux Mint 9 and it has the same error as Ubuntu 10.04. Kubuntu 10.04 on my desktop gives the same error too.

Is it really an error? Or am I doing something wrong in the process of using the e2fs* tools (tune2fs, e2label, etc.)?

SOLVED: It was just a stupid mistake by me in the device parameter I passed to the command. The device needs to be a partition, not a disk. I.e., use e2label /dev/sda1 newlabel.