create filesystem on md - RAID device

Markus Schönhaber ubuntu-users at
Tue Jan 5 13:02:25 UTC 2010

05.01.2010 13:31, Franz Waldmüller:

> Hi I got a question concerning the creation of a new filesystem on a 
> raid1 device (let's call it /dev/md7).
> I am running ubuntu 9.10 i386 desktop edition.
> I just want some advice if my approach is correct:
> if /dev/md7 is mounted as /home I intend to do the following (as root):
> umount /home
> mkfs.ext4 /dev/md7 # should I add any options?
> then I have to correct the /etc/fstab file with the new UUID of the 
> created filesystem

Sounds good.
Instead of changing the "UUID=..." part in fstab, you could use the
device node, i. e. /dev/md7, as an alternative.

> I run
> blkid /dev/md7
> And then I have to try to get this output into my fstab file. Any hints 
> how I can do this on the command line without running X? I have some 
> basic knowledge of using nano. Maybe I can run a command which attaches 
> the output of blkid to the fstab file. The only thing left would be to 
> move the UUID up to the right position in the fstab file

You could do
blkid /dev/md7 >> /etc/fstab
you'll then have to manually remove the additional stuff blkid reports,
or do something like
blkid /dev/md7 | sed -r 's,.*(UUID=)"([^"]*)".*,\1\2,' >> /etc/fstab
which should append only the UUID=... for the fs to /etc/fstab

Nevertheless, make a backup of your fstab before fiddling with it.

> after
> mount -a
> everything should be up and running again?
> Am I correct?

Don't forget to copy the data in you old /home.
Other than that, I don't see anything wrong with what you write.


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