How the Humble Drive Partition Led to the Larger Hard Drives We All Love

Apr 22

09:36

2015

Rossy Guide

While installing Windows 8, Ragav RG converted his hard drive to the new GUID Partition Table (GPT) partitioning format. This format used to define the hard disk partitions in computers with UEFI startup firmware. The GPT replaces the previous master boot record (MBR) method. While the MBR supported partitions as large as 2.2TB, GPT partitions can be up to 18 Exabyte’s. GUID stands for globally unique identifiers. Translation: Every partition has a randomly generated, 36-character Unicode name.

Before it can load an operating system, your PC needs a way of know where all of the partitions are located? Traditionally, it got that information from the drive’s Master Boot Record (MBR). The MBR is a special type of boot sector at the very beginning of partitioned computer mass storage devices that identifies how and where an operating system is located so that it can be boot (loaded) into the computer's main storage or random access memory.

The Master Boot Record is also sometimes called the "partition sector" or the "master partition table" because it includes a table that locates each partition that the hard disk has been formatted into. In addition to this table, the MBR also includes a program that reads the boot sector record of the partition containing the operating system to be booted into RAM. But new computers are eschewing MBR for a newer and more versatile technology: GPT.

And also MBR dates back to 1983, when DOS-based PCs first used internal hard drives. MBR cannot easily manage drives larger than 4TB or with more than four partitions (there are workarounds, of course). GPT, on the other hand, has limits well beyond anything you’re likely to encounter over the next few decades.

GTP is extremely unlikely that any two partitions in the world would have the same identifier. If you want to find out your drive is using GPT,

In the Start menu’s Search field or the Windows 8 Search charm, type partitions (you’ll need to type that s).
Select Create and format hard disk partitions.
In the resulting Disk Management program, right-click on the drive’s gray box on the left.
If you see a “Convert to GPT Disk” option—which will probably be grayed out—you’ve got an MBR drive and vice versa.

GPT can speed up boot time compared to MBR, but I wouldn’t make a big deal about that. It can only speed up the first few seconds of the boot. And depending on your hardware, it may not speed it up enough to be noticed.

Also what about Windows compatibility? Windows Vista, 7, and 8 can all read and write to GPT drives. But you can only boot from a GPT drive if you’re using a UEFI-based computer running a 64-bit version of Windows.

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