GPT vs MBR - GPT Explained

You may have noticed a new GPT (GUID Partition Table) formatting option on your new system. Maybe you've heard some buzz about how GPT is replacing the old school MBR option. Or maybe your geek friends at work are talking about GPT at the water cooler and you have no idea what they're rambling on about. Well, what the heck is this GPT thingy? We'll explain it here without being ridiculously technical.

Let's rewind a bit and cover the MBR. At the beginning of every hard drive there is a designated portion called the MBR (Master Boot Record). The MBR gives your system information about the drive and if/where to run your installed operating systems. Some of this information reveals details about the size and partitions on the drive. It's a method that has worked well for years, but the MBR is starting to become outdated since it can only hold enough information to define partitions on drives less than 2.2TB in size. This is where GPT steps in.

As it turns out, GPT is becoming an option out of necessity because of those size limitations of the MBR. Currently we are on the cusp of regularly pumping out hard drives larger than 2TB and we need this new partition format option so that users can use every bit of space on their huge drives. Basically, GPT reserves a portion of the hard drive, in addition to the part reserved for the MBR. GPT uses this extra space to store even more information about the hard drive and its partitions. This allows for hard drive sizes of ridiculous proportions. How large? Try 9.4ZB, or Zeta-bytes,which (if you're nerdy and really care) is 20 zeros after the "94." Basically, hard drives will be non-existent by the time we need storage that large.

The introduction of GPT created another issue. This concern is that the old-school BIOS can not boot from GPT formatted drives. Newer operating systems can read from and initialize/format drives so that this GPT format can be used as storage drives, but they just can't boot from GPT formatted drives using the old BIOS. Fortunately there is help out there. The exception is on motherboards with the new BIOS replacement, UEFI. UEFI replaces the old school PC BIOS so systems can boot from GPT formatted drives. There is more to UEFI than just allowing boot support from GPT drives, which we previously covered here. But all you need to know now, is that it can be done.

We hope you learned a little bit today, so that you're no longer in the dark when the topic of GPT comes up at the water cooler. Feel free to stop by the BURNED iN forums to talk about this and other hot tech topics.