If you create a PV directly on a virtual storage device inside a KVM guest, then you will notice that the logical volumes from the guest are visible on the hypervisor. This can make things quite confusing if you use the same logical volume and volume group names across multiple guests. You may also get some warnings on the hypervisor saying that it can't find a device.

For example, I have recreated this problem on my test hypervisor:

[root@testhost ~]# vgs Couldn't find device with uuid dCaylp-1kvL-syiF-A2bW-NTPP-Ehlb-gtfxZz. VG #PV #LV #SN Attr VSize VFree vg_main 2 2 0 wz-pn- 19.25g 768.00m vg_main 2 2 0 wz-pn- 19.25g 768.00m vg_testhost 1 8 0 wz--n- 237.98g 120.15g 

For this reason, I would advise that you use parted or fdisk to create a KVM partition on there first (as shown in a previous answer), before creating a PV and adding it to a volume group. That way, the guest logical volumes remain hidden from the hypervisor.

If you create a PV directly on a virtual storage device inside a KVM guest, then you will notice that the logical volumes from the guest are visible on the hypervisor. This can make things quite confusing if you use the same logical volume and volume group names across multiple guests. You may also get some warnings on the hypervisor saying that it can't find a device.

For example, I have recreated this problem on my test hypervisor:

[root@testhost ~]# vgs Couldn't find device with uuid dCaylp-1kvL-syiF-A2bW-NTPP-Ehlb-gtfxZz. VG #PV #LV #SN Attr VSize VFree vg_main 2 2 0 wz-pn- 19.25g 768.00m vg_main 2 2 0 wz-pn- 19.25g 768.00m vg_testhost 1 8 0 wz--n- 237.98g 120.15g 

Here you can see 2 volume groups with the same name, both from guests which shouldn't really appear on the hypervisor.

For this reason, I would advise that you use parted or fdisk to create a KVM partition on there first (as shown in the previous answer by 3dinfluence), before creating a PV and adding it to a volume group. That way, the guest logical volumes remain hidden from the hypervisor.