Partition - Technical

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The LDM manages the whole disk so an ordinary MSDOS style partition is not needed. However, to prevent legacy applications thinking that the disk is unused, Windows creates a dummy partition that fills the disk.

One of the most important legacy applications is the boot loader. It doesn't understand the LDM database, but it must still be able to boot the operating system.


If a disk is converted to a dynamic disk before any creating any partitions then Windows will create a single partition to fill the disk. Microsoft have chosen the id 0x42 which was used by the encrypted Secure FileSystem (SFS).

Device Start End Blocks Id System
/dev/hda1 1 1037 2090560 42 SFS

If a disk with partitions is converted to a dynamic disk, then the structure will be preserved. Converted disks will be limited to this structure. A case where these partitions is needed is the boot loader. It only understands MSDOS partitions.

Device Start End Blocks Id System
/dev/hda1 1 100 199773 42 SFS
/dev/hda2 101 700 1208731 42 SFS
/dev/hda3 701 1037 676001 42 SFS

Identifying an LDM Disk

The most obvious sign of dynamic disks is a partition of type 0x42. Immediately after the partition table is the Private Header (PRIVHEAD). It gives the location and size of the database. If a dynamic disk is reverted to a basic disk, then the PRIVHEADs will be removed (some of the database will remain).

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