Introduction to guid Partitioned Tables

Let's talk about the widely used disks.Partition TableSolution. TraditionalPartition Scheme(Referred to as the MBR partition solution) isPartitionSave informationDiskOf the 64 bytes in the first sector (MBR sector), each partition item occupies 16 bytes, the 16 bytes contain activity status signs, file system IDs, start and end cylinder numbers, head numbers, Fan area numbers, and hidden sector numbers (4 bytes), the total number of partitions (4 bytes) and so on. Since the MBR sector only has 64 bytes for Partitioned Tables, only information of four partitions can be recorded. This is the reason why the number of Primary partitions cannot exceed 4. Later, in order to support more partitions, the concept of extended partitions and logical partitions was introduced. However, each partition item is still stored in 16 bytes.

Isn't the MBR partitioning solution well used? Why should we propose a new solution? Let's see what's wrong with the MBR partitioning solution. As mentioned above, the number of primary partitions cannot exceed 4. In addition, the most critical issue is that the MBR partition solution cannot support disks larger than 2 TB. This solution uses four bytes to store the total number of sectors of a partition. the maximum number of sectors is 2 to the power of 32. Based on the calculation of 512 bytes per sector, each partition cannot exceed 2 TB. After the disk capacity exceeds 2 TB, the start position of the partition cannot be expressed. Today, with the rapid development of hard disk capacity, the limit of 2 TB will soon be broken through. It can be seen that the MBR partition scheme can no longer meet the needs. The following describes the guid partitioned table solution.

Guid partitioned table(GPT for short. A disk that uses a guid partitioned table is called a GPT disk. It is a new disk partitioned table structure standard derived from the EFI standard. Compared with the primary Boot Record (MBR) partitioning scheme, GPT provides a more flexible disk partitioning mechanism. It has the following advantages:
1. Large Hard Disks larger than 2 TB are supported.
2. There is almost no limit on the number of partitions on each disk. Why is it "almost? Windows allows up to 128 partitions. But it is enough.
3. There is almost no limit on the partition size. It is also an "almost ". Because it uses a 64-bit integer to represent the sector number. To put it bluntly, the partition size represented by a 64-bit integer is already an "astronomical number". You cannot see a hard disk of this size within a few years, let alone a partition.
4. The Partition Table comes with backup. At the beginning and end of the disk, an identical Partition Table is saved. After one copy is damaged, it can be restored through another copy.
5. Each partition can have a name (different from the volume label ).

Since the guid partitioning scheme has so many advantages, can this scheme be used in all partitions? No. Not all Windows systems support this partitioning scheme. See the following table:

Windows type	Can I read and write GPT disks?	Can I start a GPT disk?
32-bit Windows XP	No. Only one protective MBR partition can be seen	Not Supported
Windows 2000/NT/9x	No. Only one protective MBR partition can be seen	Not Supported
64-bit Windows XP	Yes	Only itanium-based systems can be started from the GPT Disk
Windows Server 2003 SP1 and later versions	Yes	Only itanium-based systems can be started from the GPT Disk
Windows Vista	Yes	Only the EFI-based system supports starting from the GPT Disk
Windows Server 2008	Yes	Only the EFI-based system supports starting from the GPT Disk
Windows 7	Yes	Only the EFI-based system supports starting from the GPT Disk

Are you disappointed? Currently, most PC systems cannot fully support GPT disks. However, this does not mean that we do not need to understand the guid partitioning scheme. Don't forget, the speed of hardware development is always surprising. A large number of TB hard disks have been listed, and hard disks larger than 2 TB will soon become popular, and EFI-based mainboards are also being sold. The GUID partitioning scheme will eventually become the mainstream.

As a partition software,DiskgeniusThe GUID Partition Table is supported in analyticdb 3.1. This is the first partition software in China that supports guid partition tables. Diskgenius allows you to create, delete, format, recover lost partitions, restore files, back up Partitioned Tables, convert the guid partition table format to the MBR partition table format (correct conversion).