This format supports many of the features of disk image files found in other virtualization products, such as snapshotting and sparse allocation. The Virtual Disk Image (VDI) format is the native virtual disk format in Oracle VM VirtualBox. Because of the vendor's broad industry acceptance, it's common for other virtualization products to recognize VMDK disk image files and even work natively with them. VMware publishes the spec as a "technical note" with the rest of its developer documentation, or you can request the spec online. The VMDK specification is currently in its fifth revision. For desktop virtualization admins, this means VMDK files can deliver sparsely populated volumes to a client with less overhead than other virtual disk image file formats. So, VMDKs can make more efficient use of space when they need to. (VirtualBox VDI clusters, which I'll cover next, use 1 MB pages, so the same 4K cluster would need an entire megabyte to represent it.) That means that if a single large-sector drive, such as a 4K sector, is non-zero in the file system within the VMDK, then the file only needs a 64K block to represent that cluster. VMDK volumes support snapshotting, sparse allocation (meaning that the file can expand on demand up to the maximum volume size specified at its creation) and advanced features, such as 64K sub-blocks.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |