Find FS type

ReeferMac · Guru Joined: 30 May 2004 Posts: 389

OK, this one might sound really stupid, but....
Is there a way to find out what format a partition is? I've had a problem mounting one particular partition, and can't figure out why. /etc/fstab shows it as being a different format from the rest of the system's disk's, and for the life of me I can't remember what format I made it when I setup the box.
Will it hurt a partition if I change /etc/fstab to another format type, and try to mount the partition?
Thanks.

- Mac

Cocker68 · Posted: Tue Nov 15, 2005 1:09 pm Post subject:

The mount command itself tries to find out the FS, if its not given explicitly as a parameter.
Try

ReeferMac · Guru Joined: 30 May 2004 Posts: 389

Thanks Cocker.
That's how I've been accessing the data on that partition, but mount doesn't return anything on the command line. It _does_ mount it, but nothing to std_out. I'd like it to mount through /etc/fstab so it's available every time after boot.
Is there a verbose mode or something I can turn on for mount?
Thanks again.

- Mac

i92guboj · Posted: Tue Nov 15, 2005 6:02 pm Post subject:

If the partition is mounted you can do "mount" with no arguments to see the partitions that are mounted, along with their type and mount options.

codergeek42 · Posted: Tue Nov 15, 2005 6:06 pm Post subject:

If I'm not mistaken, each filesystem's superblock has a different "magic number". I'm not exactly sure how that works but you may want to check the kernel's filesystem code or that of the specific filesyetem utilities. Hopefully that's a push in the right direction.

--Peter
_________________
~~ Peter: Programmer, Mathematician, STEM & Free Software Advocate, Enlightened Agent, Transhumanist, Fedora contributor
Who am I? :: EFF & FSF

ReeferMac · Guru Joined: 30 May 2004 Posts: 389

6thpink, you da man!

i92guboj · Posted: Tue Nov 15, 2005 9:51 pm Post subject:

Ext3/2 are fully compatible partition types. That means that you can mount any ext2 or ext3 wich any of this two types, and nothing bad will occur. Both are great, and as a rule of thumb you can use this: if that partition contain important data use ext3 (it is safer), while if this partition contains something that is not vital (like var, portage or tmp) you can live without journal, so use ext2 (that is lighter in resources and disk space, since it does not use journaling).

So, there is no problem in changing the type in fstab. If you want to transform your ext2 partition into ext3 you may want to do "tune2fs -O dir_index -j <partition>" to activate the dir_index feature and start a journal. Then change fstab to mount it as ext3. You will still be able to mount it as ext2 by specifying manually the type, as in "mount -text2 <partition> <mount_point>"

- Regards.

meyerm · Posted: Tue Nov 15, 2005 10:02 pm Post subject:

It is perhaps even ext3. But when you look into /proc/filesystems you see that the kernels tries to mount ext2 before ext3 so a ext3 partition is mounted as ext2 if you leave the choice to the kernel. Just add a "-t ext3" to the mount command to mount it explicitly as ext3.

i92guboj · Posted: Tue Nov 15, 2005 10:17 pm Post subject:

Exactly, you can also use fstab to fix ext3 as the type of that partition, then mount will always mount that partition under the directory that you select as ext3. For example:

ReeferMac · Guru Joined: 30 May 2004 Posts: 389

Thanks a ton guy's, that really clears some things up for me.
Thanks again!

- Mac