How do I find what filesystem is on a logical volume?

Question

I've installed Linux Mint 18 using logical volume management. This is my first experience with LVM. The installation process created the LV "root", and I'd like to know what filesystem exists in this LV. How do I discover this?

My normal tools - GParted, Disks, and fdisk - show only "LVM2" or "Linux LVM" as the filesystem instead of ext2/ext3/ext4. I'm sure the answer exists on the internet, but I've spent nearly an hour searching with no results since the signal-to-noise ratio of searches involving "LVM filesystem" is incredibly low.

Solution 1

The blkid command seems to be the best answer. Among its output lines is

/dev/mapper/mint--vg-root: UUID="blah" TYPE="ext4"

showing that the LV "root" has an ext4 filesystem.

Solution 2

LVM is slightly complex, but just reading through any of the many LVM tutorials and howtos should get you a lot of information.

I had quite some use of this link, in short, LVM uses a whole different set of tools than the blockdevices you're probably used to.

Try pvs, vgs, lvs and pvdisplay, vgdisplay and lvdisplay, if you look and read closely, you'll probably see patterns emerge in the Name's of different parts.

In short though, lvm breaks up a disk, kind of like partitions, those partitions are then formatted with a filesystem like ext4. LVM is therefore not a filesystem, it is a volume manager. The 'pv' in the commands stands for 'physical volume', the 'vg' for 'volume groups' and the 'lv' for 'logical volume'. These are hierarchical in nature.

I hope these hints and tips get you on started on your way to understanding LVM. (if not, don't be afraid to ask more specific questions).

Comments

[MariusMatutiae]

This is not really an answer. The question asked has a well-defined solution (blkid, from the man page: It can determine the type of content (e.g. filesystem or swap) ), and there is no need to get anyone started with tips and hints. Please try to be concrete in your answers, vague answers such as this as frowned upon on SE sites.