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I now we cannot use thin LVM volumes with libvirt. Is there any other alternative allowing use of LVM thin provisioning in KVM/QEMU virtual machines?

shodanshok
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user878965
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1 Answers1

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libvirt does not directly support using thin volumes as storage pool: when selecting the volume group where creating each logical volumes (disk images), the thin pool is not shown on the list.

To use thin volumes with libvirt, you have two possibility:

  • manually create the required thin volume, attaching it to the virtual machine;
  • otherwise, you can create a single big thin volume, formatting it with XFS, mounting it and using libvirt to create a directory-based storage pool (creating VM disk images as plain file on the XFS filesystem).
shodanshok
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  • "attaching it to the virtual machine". Do you mean during create the VM with virt-install? Thank you for your answer. – user878965 Feb 26 '20 at 19:45
  • I mean by directly specifing the required thin volume in the xml file (or using a GUI as `virt-manager` to edit it) – shodanshok Feb 26 '20 at 19:47
  • When I edit xml and try to run the VM via Cockpit, I get an error. For virt-manager, I can't even see the volume. – user878965 Feb 26 '20 at 19:59
  • In `virt-manager` you should be able to select "browse local" and to manually select the right logical volume. Otherwise, you have to edit the domain xml file. – shodanshok Feb 26 '20 at 20:44
  • I can't see any "browse local" option. All I can do is choose "Select or create custom storage" then select the pool. In the LVM pool only fat LVM volumes are listed. – user878965 Feb 26 '20 at 20:53
  • You should have a "Browse local" button as per this [image](https://www.berrange.com/wp-content/uploads/2010/05/14-virt-manager-choose-lun.png) – shodanshok Feb 26 '20 at 22:17
  • I finally found it. In fact, I have a recent version of virt-manager installed on remote computer, and "browse local" is not in the same place as on the screenshot. The button is disabled because I am on a remote computer and I believe it will be enabled if I use virt-manager locally on the server side. @shodanshok: Thank you very much for you help. – user878965 Feb 27 '20 at 02:12