CODEWITHSUNDEEP
kvmlibvirtvirshvirtual-disk
mehdix
mehdix

Reputation: 5164

Why libvirt's qcow2 storage file is much larger than the volume itself?

I am on Arch Linux and have a Windows 10 virtual machine which I orignially created with gnome-boxes. I think it uses libvirt. Currently I run it with virsh.

I noticed that the disk image representing a 40G volume for my Windows machine is 93G. This is the disk section of the XML definition of the virtual machine:

<disk type="file" device="disk">
  <driver name="qemu" type="qcow2" cache="writeback"/>
  <source file="/home/ms/.local/share/gnome-boxes/images/win10" index="2"/>
  <backingStore/>
  <target dev="hda" bus="sata"/>
  <alias name="sata0-0-0"/>
  <address type="drive" controller="0" bus="0" target="0" unit="0"/>
</disk>

And this is the description from the virsh GUI:

enter image description here

And this is the real file size:

~ ls -lh /home/ms/.local/share/gnome-boxes/images/win10
-rwxr--r-- 1 ms ms 93G 10. Feb 11:02 /home/ms/.local/share/gnome-boxes/images/win10

I would like to understand why there is this difference between the volume size on disk and what Windows and virsh report as the volume size. Eventually I would like to decreease the size.

Thank you for any help in advance.

Upvotes: 4

Views: 1045

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