LVM not showing correctly (takes up more disk space than the PV)

[mrHappyPants]

I've just managed to compress my LVs, extend my VG to my new SSD, move the LVs to the SSD and remove the old disk from the VG. All is well and good (mind you, I did kill my /home partition but it's sorted now...)

My next step was to shrink the PV (I think that's what I want to shrink???) so that I can add another partition to the SSD (to reduce compile times). See below for my current setup. I have a 35G PV with LVs totalling around 33G but the "partition" of the LVM is still 58G.

I have a feeling I'm missing something simple, but I have absolutely nfi... Any info/guidance would be appreciated

#pvdisplay 
  --- Physical volume ---
  PV Name               /dev/sda2
  VG Name               vg_desktop
  PV Size               35.00 GiB / not usable 31.81 MiB
  Allocatable           yes 
  PE Size               32.00 MiB
  Total PE              1119
  Free PE               68
  Allocated PE          1051
  PV UUID               ht42dd-eXaK-JnBo-B2bW-D8dJ-iU5C-5sb6df
   
#lvdisplay 
  --- Logical volume ---
  LV Name                /dev/vg_desktop/lv_swap
  VG Name                vg_desktop
  LV UUID                Ok3rSJ-YJSl-1Zad-zmTh-btf7-4j3l-vmFr3U
  LV Write Access        read/write
  LV Status              available
  # open                 2
  LV Size                7.84 GiB
  Current LE             251
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
   
  --- Logical volume ---
  LV Name                /dev/vg_desktop/lv_root
  VG Name                vg_desktop
  LV UUID                5gZdio-dr9i-frhV-oo2s-x2Xk-0HAY-K5sdln
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                15.00 GiB
  Current LE             480
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:1
   
  --- Logical volume ---
  LV Name                /dev/vg_desktop/lv_home
  VG Name                vg_desktop
  LV UUID                rewqnr-BIdy-kdz2-A3l4-Ci63-sIYT-0A21cs
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                10.00 GiB
  Current LE             320
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

#fdisk -s /dev/sda2 
58100969

[robwi]

Hello,

I'm not sure if I understand correctly.
Do you want to add / extend a logical volume, but you can't because you don't have sufficient space in the VG?

See man pvresize.

Regards,
Robert

[mrHappyPants]

I would like to add a primary partition on the disk for my programming files, so my aim is to shrink the... volume group..? Would that make sense? Physical Volumes are the disks, Volume Groups contain Logical Volumes, so I want to shrink the VG..?

I've tried Googling and man pages and --helps but I ran out of ideas...

[michaaa62]

Better you have all the data on the old disk in the case that something might get broken...

Now resize the partition with something like fdisk or parted. The graphical gparted is not able to handle partitions with LVM.

But give yourself room for the difference between decimal and dual GB. There is no clear evidence which numbers are used in the process. So resize the partition to be approx. 20% larger than what you are reading as the size for your PV, then again resize the PV to fill the partition, and resize a LV to fill the PV.

[mrHappyPants]

Ah, so now I can just resize the lvm2 partition?

I'll try that tomorrow, thanks!