GUID partition table(GPT)

Posted on December 7, 2007

My friend was told me that he bought a 4TB external storage recently. He used to installed Red Hat Enterprise 4, however he is having a problem mounting a 4TB external storage as '/data' patition.
After the investigation, he found the problem caused by the MBR and the solution is using GUID (globally unique identifier) partition table GPT.

What is MBR? Master Boot Record (MBR), or partition sector, is the 512-byte boot sector that is the first sector ("Sector 0") of a partitioned data storage device such as a hard disk. Basically, MBR disks can support up to four primary partitions, limit to 2TB of larger volume size.

What is GUID PT(GPT)?
In computer hardware, GUID Partition Table (GPT) is a standard for the layout of the partition table on a physical hard disk. It is a part of the Extensible Firmware Interface (EFI) standard proposed by Intel as a replacement for the outdated PC BIOS, one of the few remaining relics of the original IBM PC. EFI uses GPT where BIOS uses a Master Boot Record (MBR).
A GPT disk offers these benefits:
- Allows up to 128 primary partitions. (MBR disks can support up to four primary partitions and an infinite number of partitions inside an extended partition.)
- Allows a much larger volume size - greater than 2 TB, which is the limit for MBR disks.
- Provides greater reliability due to replication and cyclical redundancy check (CRC) protection of the partition table.

How to change a master boot record disk into a GUID partition table(GPT) disk?
Create a Windows bootable disk and copy diskpart.exe from Windows box(e.g. c:\windows\system32\ folder).

1. Back up or move all data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk. If the disk does not contain any partitions or volumes, skip to step 2.

2. Open Command Prompt.

3. Type: diskpart

If the disk does not contain any partitions or volumes, skip to step 7.

4. At the DISKPART prompt, type:

list volume

Make note of the number of the volume that you want to delete.

5. At the DISKPART prompt, type:

select volumeX

6.At the DISKPART prompt, type:

delete volume

7. At the DISKPART prompt, type:

list disk

Make note of the disk number of the disk that you want to convert to a GUID partition table (GPT) disk.

8. At the DISKPART prompt, type:

select diskX

9. At the DISKPART prompt, type:

convert gpt

Note: You can only convert basic MBR disks without any partitions or volumes into a GPT disk. Back up your data and then delete all partitions or volumes before converting the disk.

1. Change a Master Boot Record disk into GUID partition.

2. Installing and managing hard disk drives.

3. Using GPT Drives.

Possibly Related Posts:

« RPM Command

Categories How's To, Tips