What's a Disk Partition?
Hi everyone. Leo Notenboom here for askleo.com. We get wrapped up in a
lot of different terminology when it comes to computers, disks, and specifically backing up.
What I want to do today is address one term that gets used a lot. It has a number of synonyms and
it's a little bit unclear as to what it might mean in some cases. And I also want to diskuss exactly
when it's important that you even care because most of the time you don't. So the term of course
is “partition”. Now, a partition is essentially a piece if you will of a hard disk. A hard disk
can be divided up into multiple partitions, and you'll see that here in just a moment when we fire
up disk manager, and I’ll show you how that looks in Windows. I want to quickly talk about a couple
of the related terms, the terms that are sometimes confused with partition or sometimes are related
to or used in conjunction with partition. Volume is a term you'll see often and for the most part
it is synonymous with partition. You'll often hear folks talk about disk partitions and disk volumes.
They're pretty much the same thing. You'll also hear about what are called logical and physical
drives. Physical drives are what you might imagine the actual physical hard disk, or ssd
that you might have in your hand. The logical disk is what happens when you take a physical
disk and divide it into pieces. In other words, a physical disk an actual physical hard drive
can actually have multiple different logical disks, each one looking like a disk all to itself.
But they all happen to live on the same physical disk. And then finally disks and drives. Those
terms do get used interchangeably, inconsistently at best. I know I’m guilty of that myself. A disk
and a drive are essentially the same thing whether it be a hard disk, an HDD, or a solid state disk,
SSD. You'll often hear us refer to both hard disks and hard disk drives, or solid state disks,
or solid state drives. Disk drive in most cases it's the same thing. So let's go take a look at
an actual system. Here this is my Windows 10 home machine. I’m right-clicking on the start menu and
we're going to bring up disk management. Now the disk management tool is what you can use
to actually see how many disks you have and how they're laid out in terms of partitions.
Now I’m going to focus mostly on the lower part of this diagram. The upper part is really just
a list of all the partitions on your system and you'll see that they talk about both partitions
and volumes. The Microsoft folks will tell you that this is a list of all the volumes
on your machine, whereas a partition it's the same thing. Down here on this lower pane
you'll see that I actually have two disks. So each physical disk is represented as a single
line across this bottom pane. So I’ve got disk 0 and disk 1. You'll see also that the
CD-ROM drive happens to be represented as well, but our focus today is on disk 0 and disk 1.
These are two separate physical hard drives I have. This machine has two hard drives in it.
The lower one disk 1 is a single partition. In other words the single drive contains a single
partition that partition uses all of the available space on the drive. The disk 0 however is an
interesting one and it's something you'll see very very commonly in most Windows 10 systems these
days. It is a single drive. Again same size 100 gigabytes, but it's been divided up into several
separate partitions. The biggest one here in the middle of course is the partition
C:. It has most of the hard disk space, 98.88 gigabytes, but you'll see then that there are also
two separate partitions. They don't have drive letters assigned but they are in fact separate
drives. These are logical drives. Each one of these partitions is a separate logical drive
on the single physical drive that is disk 0. You can see of course that the center partition here,
the C:, has a drive letter assigned. See it's not required that partitions have drive letters
assigned. These other partitions the recovery partitions, what they call the system partition,
these are typically not used or not useful for us to be able to access in an ongoing basis. So you
don't see a drive letter. They just aren't made visible to Windows in some cases. Like this one
on the left you can right click on it and change drive letters and paths to assign a
drive letter to it. Or on this one you can see the recovery partition that's simply not an option.
But the idea is that a single drive, disk 0 in our example here, can have multiple partitions. Each
partition can have a separate space a separate amount of disk space allocated to it, and they may
or may not have drive letters assigned. Now let's look at another slightly more maybe pragmatic or
practical application. Let's take a look at this volume E that I’ve got down here, it's a single
partition. If we wanted to we could divide this disk into two partitions. I’m going to do that
using Microsoft’s tool the built-in disk manager. You can only do that by deleting the volume. The
volume or partition as it's called. We're not going to save any data. When you delete a volume
you are erasing all of the data on that volume. If you wanted to do what I’m about to do and preserve
data you'll need to use a third party tool. The Microsoft disk management tool doesn't support
doing this any other way. So I’m going to say yes. We're going to delete the volume and now we have
100 gigabytes of unallocated space. This is not unlike a disk that might have come factory fresh,
although they do sometimes come pre-formatted. But this is essentially an unformatted
unallocated disk. I’m going to right click on it again and I’m going to create a new simple volume.
It fires up the wizard to do so. I’m actually not going to allocate all of the space. This
is the maximum amount of space and you can see that it defaults to creating a single
partition that encompasses the entire drive. Instead I’m going to roughly turn this in half,
so we'll go ahead and call this 50,000 megabytes or 50 gigabytes. We'll hit next. I’ll go ahead and
let it assign a drive letter. That's fine and since we are creating a new partition the disk
needs to be formatted, and we get to choose what we want that format to be NTFS or something else.
There's some details here that we typically don't have to worry about and we get to set a new volume
label. I’m going to call this one new volume 1 for obvious reasons here in a second. A quick format
is all you need in most cases. A full format will actually write information to the entire partition
but we don't need that so I’m going to go ahead and click next. Boom! And all of a sudden now
we have two partitions on this hard disk. One of is ready to go it's our volume E the other
one is unallocated. The only thing we need to do here of course is say create a new simple volume.
We're going to go ahead and use all of the available space. We'll go ahead and give it the
assigned drive letter and we're going to call this one new volume 2. And I’m going to finish. And
poof, now we actually have E and F as two separate drives. And if we fire up Windows file explorer
you'll see that in fact on this machine we have local disk C the one we expected,
the CD drive the one we saw, and now we have two actual disk drives here E and F . So why
does this matter? Why is this important to understand? Well what I want to show you
next is a backup program. I’m going to fire up Macrium reflect the free version
and you'll see that it's opening screen actually gives us a very similar to view to
what was displayed in disk management. We have one line per physical disk. This is disk 1 up here,
and this disk 2 down here. We have boxes within each of those lines representing each of the
partitions. Here's why it matters. You can back up an entire partition and maybe only a partition.
If we uncheck the two smaller partitions at either side of our C drive and if we were to now create a
backup image that image would be of everything on the C partition and only the C partition. In other
words it would only back up this single partition. In many cases that's enough. That's fine. That's
great. My preference is that you always back up the entire disk. In other words all of the
partitions are selected so that you know that no matter what, the image you're creating is an image
of the entire hard disk and everything that was stored on it, without necessarily needing to know
what you should or should not back up. You can if you like back up individual volumes, or partitions
as they're often called, but my preference is that you actually back up the entire hard disk
the entire physical hard disk. The same is true for this other disk these are two what we would
typically refer to as data drive since our system is on C these two drives E and F you can now back
them up separately. The way it's configured right now it would take an image of only the F drive
or you can back them up together taking an image of the entire physical hard drive.
But that's what partitions are all about. They really are nothing more than a different way of
organizing the data on your machine. I hope this was helpful. For updates, for related links, for
more visit askleo.com/131019. I’m Leo Notenboom. This is askleo.com. Thanks for watching.