Why Partition your Disk Device?

List of Reasons

There are several good reasons why you might partition your disk device.

To improve performance
To install more than one Operating System
To share data among Operating Systems
To make computer maintenance tasks quicker
Caveat: Too many partitions

To Improve Performance

To improve performance, you should place frequently accessed files in a partition at the start of the hard disk drive.

Modern hard disk drives contain more sectors of data at the outer edge of the physical disk than at the inner edge. Hard drives spin at a constant rate; normally 5400, 7200, or 10,000 RPM. This physical configuration means that more data can be accessed at the outer edge (start) in a single spin of the disk than at the inner edge (end).

To take advantage of these physical hard disk drive properties, you should place frequently accessed files at the start of the disk (lower sector numbers).

For example to shorten the Operating System boot time, you should place the OS in a partition at the start of the hard disk drive. Less frequently accessed information, such as your data files, should be placed in a partition after the OS.

Note: These improved performance properties only apply to hard disk drives because these devices contain spinning disks.

For disk devices that do not contain moving parts, such as Solid State Drives (SSDs), memory sticks, and USB flash drives, you will get increased performance by aligning partitions to mebibyte (MiB) boundaries.

Aligning partitions to mebibyte (MiB) boundaries works well with modern Operating Systems and all types of disk devices.

To install more than one Operating System

To install more than one Operating System, you should create separate partitions for each OS.

Because different Operating Systems have different requirements, each OS should have a separate partition so that these individual requirements can be met.

Partition Requirements

Windows requires a primary partition for the OS.
GNU/Linux can use either a primary partition or a logical partition.
Mac OS X needs a primary partition.

File System Requirements

Windows performs optimally with NTFS.
GNU/Linux prefers file systems such as ext2/3/4, xfs, and btrfs.
Mac OS X performs optimally with HFS+.

Partition Table Requirements

As a general rule, each disk device should contain only one partition table.
Mac OS X is an exception to this rule.

Recent Windows versions, such as Windows 7, can use either a GPT or an MSDOS partition table.
Older Windows versions, such as Windows XP, require an MSDOS partition table.
GNU/Linux can use either a GPT or an MSDOS partition table.
Mac OS X uses a hybrid partition table scheme consisting of both a GPT and an MSDOS partition table.

Note: After editing partitions with GParted, the hybrid partition table scheme gets out of sync. You can re-synchronize the partition tables using the gptsync command included with GParted Live, or with the rEFIt application.

Note: On disk devices with a 512 byte sector size, an MSDOS partition table is limited to 2 TB. For disk sizes larger than 2 TB you need to use a different partition table, such as GPT.

To share data among Operating Systems, you should place your data in a file system in a separate partition that can be read from and written to by all your OSes (e.g., FAT32).

In a perfect world, all Operating Systems would be able to read from and write to all file system types. Unfortunately this is not the case. Hence if you wish to access your data from all of your OSes, you need to use a file system type that each OS can access.

The FAT16 (limited to 2 GB) and FAT32 file systems are examples of two file systems that can be read from and written to by OSes, such as Windows, GNU/Linux, and Mac OS X.

To make computer maintenance tasks quicker

To make computer maintenance tasks quicker, you should store your data in a separate partition.

Even if you do not run multiple Operating Systems on your computer, there are advantages to storing your data in a partition separate from the OS.

One advantage is that you will have at least two partitions: one containing the OS (and applications), and a second containing data, as opposed to a single larger partition. The file system on a small partition is quicker to check or defragment than a large partition. This can save you time when your computer is running file system checks to recover from a power failure, or when you are defragmenting your disk for improved performance.

A second advantage is that if all of your data is contained in a separate partition, then you can use the backup strategy that I use. Specifically, on a frequent basis I back up all of my data in my data partition, but do not back up the OS or applications.

My reasoning is that I cannot afford to lose my data, but I can lose the OS because with some effort I can re-install the Operating System and applications using the install media. Recreating my data is neither practical, nor even possible.

A third advantage to storing your data in a separate partition is that it makes Operating System upgrades quicker. Often when upgrading from one major version of an OS to another version, the process involves reformatting the partition. If your data is in the same partition as the OS, then you will have to restore your data from backup. If; however, you have your data in a separate partition, then you can skip the step to restore your data from backup.

Caveat: Too many partitions

Because managing multiple partitions can become onerous, you should only create or reserve space for as many partitions as you reasonably need.

I would be remiss if I did not tell you about the problems that can occur with too many partitions. Specifically partitions do not share free space with other partitions. Hence if one partition runs out of free space, then you will need to resize, move, or delete other partitions to enable you to address the lack of free space problem.

If there is unallocated space immediately after the partition, then growing the partition into this space is often a quick task.

Unfortunately if unallocated space is not available immediately after the partition, then the task becomes much more onerous. This is because moving partitions is a time consuming task, and there is always the chance of data loss due to software bugs, hardware problems, or power failure. We highly recommend that you back up your data prior to moving partitions.

To minimize the chance that you will need to restructure your partition layout, we recommend that you spend some time up front to estimate the partition sizes you will need.