When using most hypervisors your virtual drives grow indefinitely until they
reach their max size as the virtual machine is used. You can check the max size
of your virtual drive ls and check the actual used disk space with du.
/var/lib/libvirt/images ls -lh camera.qcow2
-rw------- 1 libvirt libvirt 401G May 27 16:29 camera.qcow2
/var/lib/libvirt/images du -h camera.qcow2
345G camera.qcow2
This particular virtual machine takes up 345Gb, but if I boot up the virtual
machine and check the file manager I'm using far less than that. When files are
deleted in a virtual machine data is not freed up on the host. Fortunately,
there's a wonderful tool called virt-sparsify that can be used to shrink the
drive. It comes as part of libguestfs which is a c library and collection of
simple tools for creating, reading, and modifying virual disk images. It works
with the vast majority of hypervisors including VMware, KVM, qemu, VirtualBox,
and Xen to name a few. It includes loads of helpful tools, but I probably use it
for virt-sparsify most often.
- Turn off your vm before using this tool.
- It works with ext2, ext3, ext4, btrfs, NTFS, but probably not rare/custom formats.
- Encrypted disks will not work.
- If you're not using the --in-place option it could require double the source image of free space while running (because it copies the disk while working).
- The --in-place option isn't quite as effective and may not work depending on your host system, but if you're shrinking a massive virtual disk it might be your only option.
sudo virt-sparsify camera.qcow2 camera-mini.qcow2