Fast Virtual Disk (FVD) is a new virtual machine (VM) image format and the corresponding block device driver developed for QEMU. QEMU does I/O emulation for multiple hypervisors, including KVM, Xen-HVM, and VirtualBox. FVD is a holistic solution for both Cloud and non-Cloud environments. Its feature set includes flexible configurability, storage thin provisioning without a host file system, compact image, internal snapshot, encryption, copy-on-write, copy-on-read, and adaptive prefetching. The last two features enable instant VM creation and instant VM migration, even if the VM image is stored on direct-attached storage. As its name indicates, FVD is fast. Experiments show that the throughput of FVD is 249% higher than that of QCOW2 when using the PostMark benchmark to create files.