MBR to GPT conversion

MBR to GPT disk conversion

Trying to format or add a brand new HDD or SSD to your computer? you will be asked to initiate the disk by choosing between MBR and GPT. MBR (master boot record) and GPT (GUID Partition Table) are the two different types of partition structures that defines how the information is stored in your hard disk (for HDD, SSD and removable devices). If you are likely to partition or format your disk, you would have to use either of these.

What is MBR?

MBR stands for Master Boot Record and it is the information available in first sector of a hard disk. This gives the primary information on where the operating system is located. It consists of a table that signifies where the partitions are formatted. This only supports legacy booting.

What is GPT?

GUID Partition Table (GPT) that uses UEFI (Unified Extensible Firmware Interface). GPT is the new standard that slowly replaces MBR with much more modern partitioning system.

Why GPT over MBR?

  1. GPT does not suffer the limitations of MBR. For starters, GPT - based drives can be much larger. GPT also allows nearly 128 partitions.
  2. GPT supports disks larger than 2 TB while MBR cannot.
  3. Modern day machines are enabled with UEFI boot by default. Also, certain models do not support legacy boot mode. In such cases, MBR image will not boot post deployment.
  4. The GPT disk partitioning style supports volumes up to 18 ExaBytes and up to 128 partitions per disk while the MBR disk partitioning style only supports volumes up to 2 terabytes and up to 4 primary partitions per disk (or three primary partitions, one extended partition, and unlimited logical drives).
  5. GPT disks are more reliable as they come with cyclic redundancy check (CRC).
  6. On an MBR disk, the partitioning and boot data is stored in just one place. If this data becomes corrupted or overwritten, recovery becomes impossible. While, GPT stores primary and secondary copies of this data across disks. This makes it easy for data recovery.

Points to be noted

  1. The GPT conversion might not be supported in older operating systems.
  2. Using GPT conversion will have the "System reserved" partition formatted to "FAT32". After formatting, if the partition size is less than 100 MB, this shall be resized to 100 MB. The resizing happens either by shrinking the OS drive or by using any unallocated space if available. Unallocated space will be available only when the target disk size is higher than the total size of the selected image partitions in the template.
  3. After GPT conversion, the target machine will boot only using UEFI. So, kindly enable UEFI boot mode in the BIOS.
  4. UEFI Secure Boot is an optional setting that enforces a signature check during the booting process. With secure boot, only the signed binaries and the matching whitelisted hashes will be executed during the booting process.

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