Shulou(Shulou.com)06/03 Report--

In the previous article, the detailed explanation of disk structure of Windows storage management introduced the disk structure of Windows and MBR. This article will introduce the structure of MBR in Windows Basic Disk to help readers better understand disk storage in Windows system.

MBR in Windows Basic Disk:

As the most important data structure in the disk, Master Boot Record is created when the disk is partitioned. The MBR consists of several parts, an executable code called Master Boot Code,Disk Signature, and a partition table for the disk. There is also a signature field at the end of the MBR that is always 0x55AA with a size of two bytes of Sector Marker. The word usually also marks the end of the extend boot record (EBR) and boot sector (boot sector).

The Master Boot Code code mainly accomplishes the following activities.

Scan the partition table of the active partition

Find the starting sector location of the active partition

Load a copy of the boot sector from the active partition into memory

Transfer control to the execution code on the boot sector

If Master Boot Code fails to perform these functions, the Windows system will throw some errors, such as "Invalid partition table", "Error loading operating system", "Missing operating system" to indicate that an error has occurred in the corresponding step.

Partition table in Basic Disk:

Partition Table in Basic Disk is a 64-byte data structure that defines the type and location of partitions on physical disks, independent of the operating system. The record of each partition table is 16 direct lengths, with a maximum of four records, each from a predefined starting position. The following example shows a record of MBR, including a display of three partition records, starting with 0x01BE, 0x01CE, and 0x01DE. The figure also shows several key fields in the partition record. 0x01C2 is System ID, which is used to define the type of logical volume. Figure 07 represents Installable File System (NTFS). The first four bytes of 0x01C6 are Relative Sectore, which represents the starting position of the logical volume. The first four bytes of the 0x01CA show the total number of sectors for the entire logical volume. Boot Indictor shows whether the partition is active.

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