A System Deployment Image (aka SDI) is a file format used primarily with Microsoft products to contain an arbitrary disk image, including boot sector information.
The System Deployment Image (SDI) file format is often used to allow the use of a virtual disk for startup or booting. Some versions of Microsoft Windows allow for "RAM booting", which is essentially the ability to load an SDI file into memory and then boot from it. The SDI file format also lends itself to network booting using the Preboot Execution Environment (PXE). Another usage is hard disk imaging.The SDI file itself is partitioned into the following sections:
SDI usually contains either Disk BLOB (HD cloning or temporary SDI) or three other of them (bootable SDI).
Windows Vista or Windows PE 2.0 boot sequence includes a boot.sdi file, which contains Part BLOB for an empty NTFS volume and a Table-of-Contents slot for the WIM image, which is stored on a separate on-disk file.
SDI files can be mounted as virtual disk drives and assigned a drive letter if an SDI driver is available to allow this. A SDI driver is a type of storage driver and is commonly used with Windows XP Embedded.
Microsoft provides a tool called the "SDI File Manager" (sdimgr.exe) which can be used for the purpose of manipulating SDI files. Some of the tasks which this tool facilitates are:
The mechanism which allows for the creation, addition and removal of virtual disk drives. SDI Loader and Driver work with Disk BLOB.