I have a single 160 GB physical hard drive. I have Windows 8.1 installed on 100 GB (Local Disk C:). I left the remaining 60 GB as unallocated space for Ubuntu installation.

Now, the problem is that when I have to assign Root, Home, Swap space on that unallocated 60 GB, I can only assign Root and Home. The remaining 20 GB is shown as unknown space. It says there can only be maximum of 4 partitions on a single drive and I have used all of them (Windows has apparently used up 2 partitions).

So, what should I do? Should I forgo the Swap space or is there any other way to get around this problem?

Please explain in layman terms if you can.

P.S : I don't want to remove Windows 8.1 from my computer but I want to dual-boot Ubuntu alongside Windows.


One of those max. 4 primary partitions can be an extended partition which in turn can hold up to 16 logical partitions. So in total you can create up to 19 usable partitions on a drive with an MBR partition table.

If you choose “something else“ as installation type, the partition manager of the Ubuntu installer lets you choose between creating primary or logical partitions:

partition creation dialogue

The partition manager will automatically create an extended partition if necessary to accommodate a newly created logical partition. It hides the complexity of dealing with this technical detail.

You should not forgo swap space:

  • If your computer runs out of physical main memory and has no swap space to fall back on, it will

    • start to kill user space processes¹ (and it's hard to predict which ones) to accommodate memory needs of the kernel and
    • behave erratically, because memory allocation for user space processes¹ will fail, which most applications aren't programmed to anticipate; this usually leads to crashes because these applications then try to access invalid memory addresses.
  • While it's possible to have a swap file inside a file system, suspension to a swap file isn't implemented in the kernel. You pretty much need a swap partition for that.

  • As I described above it's easy enough to create a swap partition if you can have up to 19 partitions on one drive – a big deal easier than dealing with the aforementioned two problems.

See also https://help.ubuntu.com/community/DualBoot/Partitions

¹ A “user space process“ is what a layman may call an “application”, but the former also encompass other things like server applications and system services.

  • So how do I make an extended partition? I mean after creating /root space, I have only one partition left. So, are you saying I should make the partition extended? How can I do that (within Windows or during Linux installation)? Can you please provide me with a good link where I can learn to do that? – Aadharsh Krishnan Oct 26 '14 at 7:02
  • As described in my answer and the Ubuntu Community Help article you can create logical partitions for Ubuntu during its installation, of which you can have up to 16. The picture in my answer shows the partition creation dialogue window of the partition manager of the installer with the radio buttons for the partition type at the top. – David Foerster Oct 26 '14 at 9:58
  • I just noticed you asked about the extended partition in particular and updated my answer accordingly. Short answer: You don't need to create one; the partition manager will do it for you. Other partition managers (e. g. GParted) often require you to create the extended partition manually. Read their manuals if you don't find the right controls by yourself. – David Foerster Oct 26 '14 at 10:12
  • Okay. I got the gist but I am still a little confused between Extended and Logical Partition. Should I assign Logical Partition for /Swap or should I create a Extended partition to solve the problem? Also, does the Linux partition manager allow me to create Extended partition while installation itself or I have to do it manually using Gparted? – Aadharsh Krishnan Oct 26 '14 at 12:46
  • Extended partitions should only be used as a wrapper for logical partitions. I feel like all the alternatives I mention are more confusing than helping you, so I'm going to do what I don't like to do: to tell people what they should do. — Just use the partition manager of the Ubuntu installer and select “logical“ as the partition type for every partition you create. Create as many partitions as you feel are necessary. The upper limit of 19 is plenty. – David Foerster Oct 26 '14 at 13:52

There can be only 4 primary partitions, but there can be many more logical partitions.

  • This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. – David Foerster Oct 26 '14 at 0:22
  • 1
    Zhis does in fact answer the question, although it's a bit short on additional information... – Jan Oct 26 '14 at 6:04
  • This answer only addresses one small part of the issue and doesn't try to answer “So, what should I do? Should I forgo the Swap space or is there any other way to get around this problem?” – David Foerster Oct 26 '14 at 9:44
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    @DavidFoerster It's saying that the OP should make logical partitions to get around the problem. This would benefit considerably from expansion. But it addresses the entirety of the question and is a real answer. More importantly, it's not an attempt to critique or request clarification. When you see an answer you think only addresses part of the question or doesn't contain enough information, even in cases where you think it should be removed, I recommend against instructing people to post it as a comment. Such answers shouldn't be comments. – Eliah Kagan Oct 26 '14 at 11:45
  • +1 I get your point. Thanks for the explanation. – David Foerster Oct 26 '14 at 12:22

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