Fast Virtual Disk (better known as FVD) is a virtualization-oriented disk image file format developed by IBM for the QEMU virtualization platform. It differs from existing paravirtualization-centric virtual disk image formats through a design that emphasizes lack of contention and separation of concerns between the host and guest kernels 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 image compression 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.
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| Optical discs |
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| Hard disks |
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| Floppy disks |
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| CD-DA | |
Convention: Any item in this table that has the form of "A+B" or "A+B+C" indicates a disk format that spans multiple files, where A contains the bulk of the data, and B and C are sidecar files. | |
