Large storage disks usually have logical partitions. An Operating System uses a partition table to identify the start address, filesystem information, and other details of a specific logical partition. The partition table in a disk is either managed in MBR or GPT format.
MBR is the legacy partition table management stuff and GPT is in use currently for modern systems compatible with UEFI.
From a user’s point of view, it comes to picture while initializing a new disk on a system it may ask you to choose between these two. So, it is important to understand what is MBR, what is GPT, and why the world has moved from MBR to GPT.
Hence, I will not be covering the technical details on how the MBR or the GPT works rather I will cover only those aspects that is relevant for a user to understand which partition table to format a disk to get the work done!
What is Partition table or What is MBR and GPT?
A mass storage device like a Hard Disk or a Solid State Drive or a USB flash drive has a very large disk space. To be able to use it wisely the whole storage space is divided into multiple logical partitions. As it is logical, there must be some data kept somewhere for reference related to its logical boundaries, the number of sectors a partition has, etc.
This logical partition data is kept in data structures in the partition table. The partition table itself could be the Master Boot Record (MBR), GPT(GUID partition table), BSD disklabels, and APM (Apple partition map), etc.
What is Master Boot Record (MBR)?
MBR generally made up of three parts, including executable code called master boot code, the partition table for the disks, and disk signature. It is the information stored in the first sector of a disk that identifies how and where an operating system will load.
MBR is also known as the master partition table because it contains the table that stores the information of the partitions.
Why MBR was replaced by GPT?
Disks are addressed in sectors whose size is 512 bytes. The address pointing to a sector is known as a Logical Block Address (LBA).
The length of a partition and the start or end address is stored in MBR as a 32-bit value. That means we can only accommodate a max address of 232. One address pointing to 512 bytes, with 232 addresses we can go to a maximum of upto 2 TiB (232 × 512 bytes).
That’s a limitation if you have a disk space more than 2 TeraBytes. GPT is the solution to overcome this problem.
GUID Partition Table (GPT)
GPT is the partition structure that uses a Globally Unique Identifier (GUIDs). Basically, a GUID is a long hexadecimal string used to identify a partition. GPT is the latest standard for the layout of the partition table of a disk.
Like the earlier MBR, GPT also addresses to a 512-bytes sector. But, the partition size has 128-bytes which can hold a very huge value of an address.
Having said that, the maximum disk size supported by GPT is about 9.4 ZB however it also depends on the operating system limitation.
There are various advantages of GPT over MBR however MBR is compatible with most of the older system and it is necessary in some cases. But going forward, GPT is the future.
That’s all for now on the difference between MBR and GPT. If you have any queries then write us in the comments below.