Fast Virtual Disk (better known asFVD) is avirtualization-orienteddisk imagefile format developed byIBM for theQEMUvirtualization platform. It differs from existingparavirtualization-centric virtual disk image formats through a design that emphasizes lack of contention andseparation of concerns between the host and guestkernels through deduplication of filesystem and block layer storage management.
FVD can be written either directly to a physical or logical blockstore (avoiding host filesystem overheads), or to a regular host file system file. It strives to maintain similarity to raw disk layouts, eliminate host filesystem and disk imagecompression overheads, and minimize metadata-related overheads.[1]
In summary, the design of FVD takes a principled approach to achieve the following benefits: Strive to make the on-disk data layout identical (or at least as close as possible) to that of a RAW image stored on a raw partition. Eliminate the overhead of a host file system when it can be avoided. Eliminate the overhead of a compact image when it can be avoided. Minimize disk I/O overhead for reading on-disk metadata by reducing metadata size. Minimize disk I/O overhead for updating on-disk metadata.