The Differences Between MBR and GPT

differences between MBR and GPTIf you might have dabbled along with your hard disk and it is always doing formatting and partitioning, surely you will come across the word “MBR” and “GPT”. This is especially evident when you're dual-booting your Mac and faced with the problem of experiencing to switch from GPT to MBR. You probably are wondering, which are the differences between MBR and GPT and it is there any benefit using one on the other? We wil clear your doubt in this post.

Hard Disk Partitions

You probably know that you can split your hard disk drive into several partitions. The question is, how does the OS have in mind the partition structure of the hard disk? That information has to come from some place. This is where MBR (Master Boot Record) and GPT (Guid Partition Table) come up. While both are architecturally different, both take part in the same role in governing and provide information for your partitions in the hard disk.

Master Boot Record (MBR)

MBR will be the old standard for managing the partition in the hard drive, and it is still being used extensively by many people. The MBR resides on the very beginning of the hard drive and it props up information on how the logical partitions are organized inside the storage device. In addition, the MBR also contains executable code that can scan the partitions for your active OS and group the boot up code/procedure for your OS.

For a MBR disk, you are able to only have four primary partitions. To create more partitions, you'll be able to set your fourth partition because the extended partition and you'll be able to create more sub-partitions (or logical drives) there. As MBR uses 32-bit to record the partition, each partition can only go up to some maximum of 2TB in size. This is how a typical MBR disk layout appears to be:


There are a couple of pitfalls with MBR. First of all, you'll be able to only have 4 partitions in the hard disk drive and each partition is limited to only 2TB in space. This is not going to operate well with harddrive of big space for storage, say 100TB. Secondly, the MBR is the only place that holds the partition information. If it find yourself getting corrupted (e-mail, it may get corrupted effortlessly), the entire hard disk is unreadable.

GUID Partition Table (GPT)

GPT is the latest standard for planning the partitions of a harddrive. It makes use of globally unique identifiers (GUID) to define the partition in fact it is part with the UEFI standard. This means that on the UEFI-based system (which is required for Windows 8 Secure Boot feature), it really is a must to make use of GPT. With GPT, you are able to create theoretically unlimited partitions on the hard disk, while it's generally on a 128 partitions by most OSes. Unlike MBR that limits each partition just to 2TB in dimensions, each partition in GPT hold up to 2^64 blocks long (as it's using 64-bit), that is equivalent to 9.44ZB for any 512-byte block (1 ZB is 1 billion terabytes). In Microsoft Windows, that size is restricted to 256TB.


From the GPT Table Scheme diagram above, it is possible to see that you will find there's primary GPT in the beginning of the hard disk drive and a secondary GPT in the end. This is what makes GPT more useful than MBR. GPT stores a backup header and partition table on the end from the disk so it might be recovered if your primary tables are corrupted. It also accomplish CRC32 checksums to detect errors and corruption of the header and partition table.

You can also see that there's a protective MBR on the first sector of the hard disk drive. Such hybrid setup is to allow a BIOS-based system to boot from a GPT disk using a boot loader stored inside the protective MBR’s code area. In addition, it protects the GPT disk from damage by GPT-unaware disk utilties.

OS Support

Intel Macs are employing GPT automatically and you won’t be capable of install Mac OS X (without tweaks and hacks) over a MBR system. Mac OS X will run on MBR disk though, it is only that you won’t be in a position to install onto it.

Most Linux kernels feature support for GPT. Unless you are compiling your own personal kernel and you also didn’t add this feature in, you need to have no problem taking your favorite distro to function in GPT disk. One thing to note, you wil have to utilize Grub 2 as the bootloader.

For Windows, only the 64-bit version of Windows from XP onward support booting from GPT disk. If you are finding a laptop pre-installed with 64-bit Windows 8, almost certainly it is using GPT. For Windows 7 and earlier version, the default configuration is going to be MBR as opposed to GPT.


In most all cases, you will likely be fine with either MBR or GPT. It is only in situation in places you need to install Windows on the Mac, or when you need to have a partition larger than 2TB, that you simply need to make use of GPT, or convert MBR to GPT. Also, for the newer style of computer that utilizes UEFI, it is going to only support GPT.

If you might have any question, go ahead and ask inside comments below and we will likely be around to reply to your question.

Title Post: The Differences Between MBR and GPT
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