LVM - Logical Volume Size inconsistency

Why results are different by using these tools on Logical Volume ?

Using Gnome Disks

Size: 14 GB — 1.4 GB free (90.3% full)
Device: /dev/UmrVolumeGroup/LV_root

Using Dolphin File Manager

Using df Command

df /dev/UmrVolumeGroup/LV_root
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/UmrVolumeGroup-LV_root ext4 14G 12G 654M 95% /
total - 14G 12G 654M 95% -

I have single SSD , having three logical volumes home, swap and root. Trying to extend root LV, command finished successfully but got inconsistent results.


This can’t be what you’re running, because df shows sizes in 1K-blocks by default, not M or G.

OK, using an alias for df

I had a similar problem where I was able to add space via a new PV to a VG, Yet df showed no increase in space. The solution for me was to extend an existing LV with:
$ sudo lvextend -r /dev/fedora_localhost-live/root /dev/mmcblk0p3 [NOTE: the LV & PV shown are specific to my installation]

When someone does an lvextend command the filesystem does not automatically get resized as well unless you use the option to do so. As a result commands to show the lv size will show the new size but commands to show the filesystem size will still see the old size.

The solution is to always use lvextend with the -r option which will do both parts at the same time. If you forget the -r option then you can do the filesystem part afterwards with resize2fs after the lvextend command completes.

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