Welcome to the ITFreeTraining video on MBR and GPT partition tables. A partition table
forms the low level structure that must be present before a hard disk can be formatted
and data copied on it. A lot of operating systems will make the choice on which partition
table to use and you may not have been aware there are two different partition tables available.
By the end of this video you will understand how these different partition tables work
and what features are available on each.
Before a hard disk can be used it needs to have a partition scheme configured on it.
The partition scheme allows the hard disk to be divided up into partitions. Let’s
take a typical hard disk like the one shown. The hard disk contains space that can be used
for data. Before this space can be used, it needs to be divided up into partitions.
Once a partition is created, it can be formatted by the operating system and data stored on
it. There are two different partition tables that are available. These are, MBR and GPT.
MBR is the older of the two and thus has the most compatibility with operating systems
and hardware. GPT is the newer standard and has more features but requires certain hardware
in order to work. To start with, I will look at MBR.
The MBR or Master Boot Record was first introduced on PC’s back in 1983. Since then it has
become the de facto standard on PC’s for hard disks and thus offers great compatibility.
MBR allows the hard disk to be divided up into 4 partitions.
One of these partitions can be changed into what is called an extended partition. An extended
partition in the old MS DOS days could contain an additional 23 partitions taking the total
number of partitions to 26 to match the number of available drive letters. This was a limitation
of DOS, however alterative operating systems were able to create more than 23 partitions
if for some reason you required that many.
As a partition table, the MBR system offers some good features and has great support but
has one major limitation in modern computing, this is that it is limited to 2 Terabytes
of usable space. If you were to install a hard disk larger than 2 Terabytes you could
use the hard disk with MBR, however any space after 2 Terabytes would be lost. You can see
that all though MBR can offer the basic features a user requires, its days are numbered due
to the limitation of how much hard disk space it can access.
The replacement for MBR is GPT or GUID Partition table. GPT supports 128 partitions without
the need to change an existing partition into an extended partition like MBR requires. GPT
supports hard disks sizes in Zettabytes. The actual amount varies depending on what size
the hard disk manufacturer makes the sectors on the hard disk, but either way a Zettabyte
is a lot of data. Currently with Terabyte hard disks on the market, first a Petabyte
and Exabyte hard disks need to be made before we get close to a Zettabyte hard disk.
If you want to boot your operating system from a hard disk using a GPT partition table,
you first need to meet some requirements. Firstly you need a bios that supports Unified
Extensible Firmware Interface or UEFI. UEFI was designed as a replacement for the previous
system called Bios. UEFI manufacturers generally offer backward compatibility with Bios, however
UEFI does require 64bit hardware to boot off and a 64bit operating system.
For boot support you need Windows XP Professional or Windows Server 2003 or above and they need
to be the 64bit version. If you are using Linux, most modern 32bit and 64bit Linux systems
will support booting from GPT hard disks or the GPT hard drive being used as a data drive.
You will need to check the details of your particular distribution to see if it is supported.
What this essentially means is that if you want to boot off a hard disk that is larger
than 2 Terabytes you will need to use GPT hardware and have operating system support.
However, even if your system does not support these requirements, many operating systems
will support GPT as a data drive. Windows Vista and Windows Server 2003 with service
pack 1 will support GPT as a data drive even on a 32bit system without hardware support.
In the real world, if you have a drive less than 2 Terabytes, MBR should meet all your
needs. There is no need to change to GPT. If however you do find that you need to convert
between the two, it is possible in Windows, however this will require all the partitions
to be created which will erase all the data on the drive.
If you are using Linux it is possible to convert the partition table without losing data, however
you should always backup your data beforehand just in case. Lastly, there is 3rd party software
available that will perform the conversion if you are willing to pay for it.
In a next video I will look at how disk management is handled with MBR and GPT disks in Windows and, all
though not required for the Microsoft exam, I will look at using linux to convert a MBR
boot partition to GPT. Well I hope you have found this video useful
and hope to see you in the next video. Bye for now.