The cases in which these two acronyms meet, GPT and MBR, are substantially three: - when you need to format a new external or internal disk;
- when trying to install Windows 10 or Windows 7 and 8 and an error appears saying that Windows cannot be installed on a GPT partition ;
- when there are computer startup errors affecting the MBR, i.e. the Master Boot Record.
MBR and GPT are acronyms in English that identify two types of disk drive partition styles .
As seen in the guide to initialize and format a new disk, when configuring a partition or disk on Windows 10 or 8.1 you are asked whether to use MBR ( Master Boot Record ) or GPT ( GUID Partition Table ).
The partition structure defines how the information is structured about the partition, where the partitions start and end and also what code is used to boot the computer, if it is a partition it is bootable.
In other words, MBR and GPT are two different ways of storing partitioning information on a disk .
GPT stands for GUID Partition Table, is the new standard that is gradually replacing the MBR, is associated with UEFI (the BIOS replacement) and has many advantages, including support for larger drives that is required by most of modern PCs.
MBR stands for Master Boot Record and is the oldest structure (born in the early 1980s).
The only reason MBR is still used is compatibility, because it definitely works with every version of Windows and other operating systems.
The main difference between GPT and MBR is related to the limits of MBR that GPT does not have.
In particular that of the disk size limits for MBR, which cannot be larger than 2TB.
MBR stands for Master Boot Record which is the special boot sector located at the beginning of the partition, which contains code called the boot loader for the installed operating system and information about the logical partitions of the drive.
An MBR disk is much more prone to boot problems because partitioning and boot data are stored in one place.
If this data is overwritten or corrupted, the computer will not start and the MBR must be repaired.
MBR also supports only up to four primary partitions and to create more, you need to transform one of the primary partitions into an "extended partition" and create logical partitions inside it.
GPT stands for GUID Partition Table, associated with UEFI, and replaces the old MBR partitioning system with something more modern.
It is called the GUID Partition Table because each partition on the drive has a global unique identifier or unique GUID.
GPT has no MBR limits and all 2TB and more hard drives (SSDs) and more of available space must be GPT based.
GPT also allows for an almost unlimited number of partitions (although Windows allows you to create a maximum of 128 partitions).
GPT also stores the cyclic redundancy check (CRC) values to verify that the data is intact.
If the data is corrupt, GPT may notice the problem and attempt to recover the damaged data from another location on the disk.
With MBR there is no prevention system and when there is a problem the computer simply does not start anymore or the partitions disappear.
So if, in theory, GPT would always be preferred, in practice the first choice of Windows when creating a new partition still remains MBR because it has more compatibility and works on everything .
For example, if you try to install 32-bit Windows on a UEFI-based computer, you cannot use the partition structure of GPT and the error mentioned above appears (the error can be corrected by converting the drive GPT to MBR using the Diskpart command on the DOS prompt)
In other words, booting from GPT is only supported by 64-bit Windows 10, Windows 7 and 8 on UEFI-based computers, as well as newer Linux distros and Macs.
To know what type of partitioning a disk uses on Windows PC, you can open Disk Management from the Start menu or from Control Panel> administrative tools> Computer Management and then press one of the disks with the right mouse button (not on the partitions but on Disk 0, Disk 1 etc.), go to Properties and to the Volumes tab, check if the partition style is MBR or GPT.
If we have a computer that supports GPT (therefore with 64-bit system), it is possible to convert the main disk drive from MBR to GPT to switch from BIOS to UEFI using the utility included in Windows 10 called MBR2GPT, without deleting anything ( as explained in the linked guide).
Alternatively you can use one of the programs to manage partitions such as AOMEI Partition Assistant or EaseUS Partition Master.
A backup of the data when doing these operations is however a must.
