After you have used a computer for a while, you may hear about the concept of disk partitioning. People often have questions like, "How many partitions should I have on my hard drive, what should I use each one for, and how big should each of them be?"
Although these questions are common, unfortunately no single simple answer is right for everyone. Many people explain how they partition their drives, but that answer may not necessarily be best for the person asking. (In fact, in many cases the partitioning approach isn't even right for the person responding!)
Learn the Lingo
First, let's get the terminology right. Some people ask "should I partition my drive?" That's the wrong question, because the terminology is a little strange. Some people think that the term "partition" means to divide the drive into two or more partitions. That's not correct: when you partition a drive you create one or more partitions on it.
You have to have at least one partition on it to use a drive. Those people who think they have an unpartitioned drive actually have a drive with only a single partition on it, which is normally called C:. The real choice is whether to have more than one partition, not whether to partition at all, since every drive has one partition.
A Bit of Computing History
Back before Windows 95 OEM Service Release 2 (also known as Windows 95B) was released in 1996, all MS-DOS and Windows hard drives were set up using the FAT16 file system (except for very tiny ones using FAT12). Because only 16 bits were used for addressing, FAT16 has a maximum partition size of 2 GB.
Hard drives larger than 2GB were rare in those days, but if you had one, you had to have multiple partitions to use all the available space. But even if your drive was no bigger than 2GB, FAT16 created another severe problem for many peoplethe size of the cluster was bigger if you had a bigger partition. Cluster sizes went from 512 bytes for a partition no bigger than32Mb all the way up to 32Kb for a partition of 1Gb or greater.
The larger the cluster size, the more space is wasted on a hard drive. That's because space for all files is allocated in whole clusters only. If you have 32Kb clusters, a 1-byte file takes 32Kb, a file one byte larger than 32Kb takes 64Kb, and so on. On the average, each file wastes about half of its last cluster.
So large partitions create a lot of waste (called "slack"). With a 2GB FAT16 drive in a single cluster, if you have 10,000 files, each wasting half of a 32Kb cluster, you waste about 160Mb to slack. That's a substantial portion of a drive that probably cost over $400 back in 1996around $32 worth.
So what did people do? They partitioned their 2GB drive into two, three, or more logical drives. Each of those logical drives was smaller than the real physical drive, had smaller clusters, and therefore less waste. If, for example, they could keep all partitions under 512Mb, cluster size was only 8Kb, and the waste was reduced to a quarter of what it would otherwise be.
People partitioned for other reasons too, but back in the days of FAT16, this was the main reason for doing so.
Working with Today's Computers
Three things have changed dramatically since 1996:
1. The FAT32 and NTFS file systems have come along, permitting larger partitions with smaller clusters, and therefore much less waste. In fact, with NTFS, cluster sizes are 4K, regardless of partition size.
2. Hard drives have become much bigger, up to 1Tb (1000 GB) in size.
3. Hard drives have become much cheaper. For example, a 500 GB drive can be bought today for around $100. That's 250 times the size of that typical 2 GB 1996 drive, at about a quarter of the price.
What those things mean together is that the old rationale of having multiple partitions to avoid substantial waste of disk space is gone. The amount of waste is much less than it used to be and the cost of that waste is much less. For all practical purposes, almost nobody should be concerned about slack anymore, and it should no longer be considered when planning your partition structure.
How to Use Partitions Now
People set up multiple partitions in a wide variety of different ways. Some of these uses are reasonable, some are questionable, and some are outright bad. Here are a number of reasons for creating multiple partitions.
1. A partition just for Windows
Most people who create a separate partition for Windows do so because they believe that if they ever have to reinstall Windows cleanly, at least they won't lose their data and they won't have to reinstall their applications, because both are safe on other partitions.
In fact the first of those thoughts is a false comfort, and the second is downright wrong. (See the discussion of partition types 2 and 4 below to find out why.)
As time passes, many people find their Windows partition that started out to be the right size turns out to be too small. For example, if you have a separate Windows partition, and you later upgrade to a newer version of Windows, you may find that your Windows partition is now too small.
2. A partition for installed programs
This normally goes hand-in-hand with partition type 1, a partition for just Windows. The thought that if you reinstall Windows, your installed application programs are safe if they are in a separate partition is simply wrong. That's because all installed programs (except for an occasional trivial one) have pointers to them within Windows, in the registry and elsewhere, as well as associated files buried within the Windows folder. So if Windows goes, the pointers and files go with it. Since you have to reinstall programs if you have to Windows, this rationale for a separate partition for programs doesn't work. In fact, there is hardly ever a good reason for separating Windows from application software in separate partitions.
3. A partition for the swap file.
Some people erroneously think that having the page file on a separate partition will improve performance. That is also false. It doesn't help, and it actually often hurts performance because it increases the drive head movement to get back and forth from the page file to the other frequently-used data on the drive. For best performance, the page file should normally be on the most-used partition of the least-used physical drive. For almost everyone with a single physical drive, that's the same drive Windows is on: C:.
4. A partition for backup of other partitions.
Some people make a separate partition to store backups of their other partition(s). People who rely on such a "backup" are just kidding themselves. It's only slightly better than no backup at all because it leaves you susceptible to simultaneous loss of the original and backup to many of the most common dangers: head crashes and other kinds of drive failure, severe power glitches, nearby lightning strikes, virus attacks, even theft of the computer. In my view, a secure backup needs to be on removable media and not in the computer at all.
5. A partition for data files
When I discussed separating Windows on a partition of its own, I pointed out that separating data from Windows is a false comfort if it's done with the thought that the data will be safe if Windows ever has to be reinstalled. The reason I call it a false comfort is because I fear that many people will rely on that separation, think that their data is safe there, and therefore not take appropriate steps to back it up.
In truth your data is not safe if it's on a separate partition. Having to reinstall Windows is only one of the dangers to a hard drive, and not even the most likely one. This kind of "safeguard" falls into the same category as a partition for backup of other partitions. It leaves you susceptible to simultaneous loss of the original and backup to many of the most common dangers that affect the entire physical drive, not just the particular partition. Safety comes from a strong backup regimen, not from how you partition.
However for some people it can be a good idea to separate Windows and programs on the one hand from data on the other, putting each of the two types into separate partitions. I think that most people's partitioning scheme should be based on their backup scheme, and backup schemes generally fall into two types: imaging the entire hard drive or backup of data only. If you backup your data only, that backup is usually facilitated by having a separate partition with data only. Then you can back up just that partition easily, without having to collect bits and pieces from here and there. On the other hand, for those who backup by creating an image of the entire drive, there is usually little, if any, benefit to separating data in a partition of its own.
By the way, in all fairness, I should point out that there are many well-respected people who recommend a separate partition for Windows, regardless of your backup scheme. Their arguments haven't convinced me, but there are clearly two different views here.
6. A partition for picture or music files
Some people like to treat pictures and videos as something separate from other data files, and create a separate partition for them. To my mind, a picture is simply another kind of data, and there is no advantage in doing this. The same goes for music files. They are just another kind of data and should be treated the same way as other data.
7. A partition for a second operating system to dual-boot to.
For those who run multiple operating systems (Windows Vista, Windows XP, Windows 98, Linux, etc.), a separate partition for each operating system is essential. The issues here are beyond the scope of this article, but it's sufficient to note that I have no objection at all to such partitions
Partitioning and Performance
Some people have multiple partitions because they believe that it somehow improves performance. That's not correct. The effect is probably small on modern computers with modern hard drives, but if anything, the opposite is true: more partitions mean poorer performance. That's because normally no partition is full and there are therefore gaps between them. It takes time for the drive's read/write heads to traverse those gaps. The closer together files are, the faster the access to them will be.
Using Partitions for Organization
I think many people overpartition because they use partitions as an organizational structure. They have a strong sense of order and want to separate apples from oranges on their drives.
Yes, separating different kinds of files on partitions is an organizational technique, but so is separating different kinds of files into folders. The difference is that partitions are static and fixed in size, while folders are dynamic, changing size automatically as necessary to meet your changing needs. That generally makes folders a much better way to organize, in my view.
True, partitions can be resized when necessary, but except with Windows Vista, doing so requires third-party software (and the ability to do it in Vista is primitive, compared to the third-party solutions). Such third-party software normally costs money, and, no matter how good and how stable it is, affects the entire drive, entailing a risk of losing everything. Plan your partitions well in the first place, and no repartitioning should be necessary. The need to repartition usually comes about as a result of overpartitioning in the first place.
What frequently happens when people organize with partitions instead of folders is that they miscalculate how much room they need on each such partition, and then when they run out of room on the partition where a file logically belongs, while still having lots of space left on the other, they simply store the file in the "wrong" partition. Paradoxically, therefore, that kind of partition structure results in less organization rather than more.
If you've read what came before, my conclusions won't come as a surprise:
1. If your backup scheme is to image the entire drive, have just a single partition (usually C:).
2. If you just backup data, set up two partitions: one for Windows and installed application programs (usually C:), and the other for data (usually D:).
In my opinion, except for those running multiple operating systems, you seldom get any benefit to having more than two partitions.