Posted July 21, 20213 yr I ran across an article whose author claimed that on recent versions of qemu, discard=unmap was functional on virtio disks. So I did some testing. I have not run all permutations, but have tested: Unraid 6.9.2 UEFI and Seabios VMs Q35-5.1 and i440fx-5.1 VMs Windows 10 and Windows 11 with the latest virtio drivers, virtio-win-0.1.196.iso Ubuntu 21.4 raw and qcow2 vdisks vdisks on XFS and BTRFS disks vdisks with and without the copy-on-write attribute set In all cases, the virtio disk was functionally equivalent to a virtio-scsi disk. On file deletion, windows unmapped blocks immediately. Linux unmapped blocks after running fstrim. https://chrisirwin.ca/posts/discard-with-kvm-2020 Edited July 21, 20213 yr by aim60
May 11, 20241 yr Hello, Doesn't work for me Quote <emulator>/usr/local/sbin/qemu</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='writeback' discard='unmap'/> <source file='/mnt/user/domains/Gaming/vdisk1.img'/> <target dev='hdc' bus='virtio'/> <boot order='1'/> <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/> </disk> Can you help me ? Edited May 11, 20241 yr by thymon
May 12, 20241 yr If you have the space copy the vdisk elsewhere, then copy back using cp --sparse=always, that will confirm if the vdisk growing is the problem.
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