Hard drive structure
Before we start explaining the different filesystem structures, we need to illustrate the different parts in a partitioned hard drive in Windows OS. The following figure illustrates simply the structure of a whole partitioned hard drive:
Master boot record
The master boot record is the first sector (512 bytes) of the hard drive. It contains, besides the boot code, all the information about the hard drive. One of the important pieces of information that can be found in the MBR is the partition table, which contains information about the partition structure in the hard drive, and for each partition, it can tell where it starts, its size, and type.
The investigator can check the existing partition with the information in the MBR and the printed size of the hard drive for a match. If there is some missing space, the handler may assume the presence of an intended action to hide some space contains usually some related important information.