Windows 7qcow2 Best

: qemu-img create -f qcow2 -o preallocation=metadata windows7.qcow2 40G

qemu-img create -f qcow2 -o size=50G,compression=zlib,encrypt=format=qcow2 windows7.qcow2 windows 7qcow2 best

. This ensures the file structure is laid out on the host disk beforehand without occupying the full capacity of the virtual disk immediately. Caching Modes: cache=none cache=writeback windows 7qcow2 best

: Use virtio-blk or virtio-scsi + qcow2 + cache=unsafe (only for non-critical test VMs) for max throughput. windows 7qcow2 best