Many computer users are familiar with the basic idea of filesystems. A storage device is divided into partitions each formatted to a particular filesystem that holds files. Just as the filesystem hold the files, a partition table holds the filesystems. There are a few partition table types.
Master Boot Record (MBR) – Most IBM-based PC storage units use this partition table format (such as thumb-drives and SD cards). MBR is often referred to as the msdos partition table. The MBR can only support storage devices up to two terabytes. MBR supports the concept of logical and primary partitions. A storage unit with the MBR table can only have up to four primary partitions. Many users wanting to make a multiboot system with more than four Linux distros often have the problem of not being able to support more partitions. Remember, logical partitions cannot be made bootable. Multiboot systems must use a different partition table discussed later.
GUID Partition Table (GPT) – Some IBM-based PC storage units have GPT, although it is usually because the user reformatted from MBR to GPT. However, most Intel and ARM-based Mac systems use GPT by default. The GPT partition table offers many improvements over MBR. GPT can support storage units up to over nine zettabytes. GPT is also the most highly recommended partition table for computers needing more than four operating systems on one hard-drive. For example, if a computer with a ten terabyte hard-disk is meant to be a multiboot system for seven different Linux distros, then GPT should be used. Most Unix and Unix-like operating systems can fully support GPT. However, most Windows systems cannot run on a GPT partition table. As for Mac systems, only the Intel and ARM-based ones can boot from GPT.
Apple Partition Map (APM) – The PowerPC-based Mac systems can only boot from APM partition tables. This is usually referred to as the Mac or Apple partition table. Linux and Intel-based Macs can use APM. Windows does not support APM.
Amiga rigid disk block (RDB) – Amiga systems use the RDB partition table. These partition tables support up to about 4*10^19TB. That is forty quintillion terabytes.
AIX – The AIX partition table is used by proprietary AIX systems. By default, Linux does not natively support the AIX partition table.
BSD – BSD Unix systems can use the BSD partition table. Linux and Windows cannot read BSD partition tables.
Others – Some other partition table formats are listed below. The below listed are very rarely used. Not much information can be seen on the Internet about them.
- dvh
- humax
- pc98
- sgi
- sun
Formatting a Partition Table
There are many ways to change/set a partition table. We will use the GUI interface.
To change or reformat a partition table, use Gparted and click “Device > Create Partition Table”. Then, choose the desired partition table.
WARNING: Changing the partition table will erase the filesystems, partitions, and files. This is a more “low-level” format. However, the files are not truly gone (there are ways to recover such files, but that is beyond the scope of this article).
You may also be wondering which is the best one for you. Well, use MBR with Windows and portable storage devices, APM on PowerPC Macs, RDB on Amiga, and GPT on all other systems.