How to reduce Volume Group size in LVM?

[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? ...)?