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[root@localhost ~] vgdisplay
  --- Volume group ---
  VG Name               vg_root
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  7
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                3
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               297,59 GiB
  PE Size               4,00 MiB
  Total PE              76182
  Alloc PE / Size       59392 / 232,00 GiB
  Free  PE / Size       16790 / 65,59 GiB
  VG UUID               XXXXXXXXXX

PV:

[root@localhost ~] pvdisplay

  --- Physical volume ---
  PV Name               /dev/mapper/udisks-luks-uuid-ASDFASDF
  VG Name               vg_root
  PV Size               297,59 GiB / not usable 2,00 MiB
  Allocatable           yes 
  PE Size               4,00 MiB
  Total PE              76182
  Free PE               16790
  Allocated PE          59392
  PV UUID               YYYYYYYYYYY

So I have a VG with 65 GByte free space. But when I want to shrink this Volume Group about ~50 GByte:

pvresize -tv --setphysicalvolumesize 247G /dev/mapper/udisks-luks-uuid-ASDFASDF
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
    Using physical volume(s) on command line
    Test mode: Skipping archiving of volume group.
    /dev/mapper/udisks-luks-uuid-ASDFASDF: Pretending size is 517996544 not 624087040 sectors.
    Resizing volume "/dev/mapper/udisks-luks-uuid-ASDFASDF" to 624087040 sectors.
    Resizing physical volume /dev/mapper/udisks-luks-uuid-ASDFASDF from 0 to 63231 extents.
  /dev/mapper/udisks-luks-uuid-ASDFASDF: cannot resize to 63231 extents as later ones are allocated.
  0 physical volume(s) resized / 1 physical volume(s) not resized
    Test mode: Wiping internal cache
    Wiping internal VG cache

So the error message is:

cannot resize to 63231 extents as later ones are allocated.

Q: How can I defrag the vg_root so I can remove the unneeded part of it?

p.s: I already found out that I only need to resize the PV to resize the VG, or are there any better commands to do the VG resize (ex.: what can I do if I would several VG's on a PV? ...)?

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4 Answers 4

up vote 16 down vote accepted

You can use pvmove to move those extents to the beginning of the device or another device:

sudo pvmove --alloc anywhere /dev/device:60000-76182

Then pvmove chooses where to move the extents to, or you can specify where to move them.

See pvs -v --segments /dev/device to see what extents are currently allocated.

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These are all the steps required to resize a LVM or LVM2 partition -

sudo lvresize --verbose --resizefs -L -150G /dev/ubuntu/root

sudo pvresize --setphysicalvolumesize {any size here} /dev/sda5

/dev/sda5: cannot resize to xxxxx extents as later ones are allocated.

You have to rearrange the unallocated space at the end of the LVM. That means after root and swap_1 partition. So, you need to move that free space using the command below

pvs -v --segments /dev/sda5

This will show the output like below
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g 0 xxx root 0 linear /dev/sda:0-xxx
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g xxx yyyy 0 free                          
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g yyyy end swap 0 linear /dev/sda5:yyyy-end

Now use the command below to remove external fragmentation -

sudo pvmove --alloc anywhere /dev/sda5:yyyy-end

Now let us see how it goes -

pvs -v --segments /dev/sda5

This will show the output like below
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g 0 xxx root 0 linear /dev/sda:0-xxx
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g xxx yyyy swap 0 linear /dev/sda5:xxx-yyyy
/dev/sda5 ubuntu lvm2 a-- 698.04g 150g yyyy end 0 free

After that use the gparted and resize the LVM to maximum used area and rest will be in unallocated space. Enjoy...

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This older post covers this sort of shrinking so you can use the new space for something else. You'll need to resize it to the data however before. This should cover that and other errors you get as well. As it's older, do read through first:

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i use this method , not sure if it's the best but works for me

use it with caution and not SysAdmin

calculate the difference that cause the problem

324%4 = 0 no problem

but

324%32 = 10.125

that's the problem so it doesn't fit

i think it's called "get real number"

lvmdiskscan

to list involved partitions

then

pvresize /dev/*** --setphysicalvolumesize ***M

i have to add extra 4M to work , i think it's related to the old PE size

finally

vgchange -s 32M **
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