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I have three partitions on my hard drive. including the system reserved partition, there are 4 Primary partitions and I cant have any more. But I want to have one 110GB Primary partition.(I want to dual boot Linux Mint with windows)

So , using easeUS , I resized one of my partitions to have a 110GB unallocated space. When I wanted to add partition in that space the app told me to make the partition that was shrunk, Logical. so I did that. added the new partition and applied the changes.

Now i have 3 primary partitions, and two Logical ones.

The problem is that when I want change that 110GB partition to Primary it tells me that there are no MBR slots. But there are only 3 Primary partitions and I should be able to do that.

what am i doing wrong?

Or are there any other ways to have that Primary partition.

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It's not MBR *"slots", but entries.
There are a total of four partition entries in the MBR.

Now i have 3 primary partitions, and two Logical ones.

So that is a total of four partition entries: three primary partitions (that you are aware of) and one extended partition that contains the two logical partitions.

what am i doing wrong?

You're ignoring the existence of the extended partition, which occupies one of the four partition entries.

Or are there any other ways to have that Primary partition

Four entries is the MBR limit.

But I want to have one 110GB Primary partition.(I want to dual boot Linux Mint with windows)

You do not need a primary partition to install Linux.
You can install Linux in logical partitions. GRUB does not require the Linux OS to be installed in a primary partition, and the Linux OS installer can use logical partitions for the root filesystem as well as the swap partition.

  • I was trying to do that the whole day cause someone had written somewhere u cant install it on a logical disk! i was such an idiot...well , thank you! – Faridzs Aug 11 '15 at 21:23
  • @Faridzs At one point in time, it was a bit difficult to run on a logical partition and sometimes a primary boot partition could be needed, but that is no longer the case. It could be that you stumbled upon old info or that someone is just repeating out-of date information. – AndrejaKo Aug 11 '15 at 22:49
  • Logical disk is usually used to describe something unrelated ("virtual" disks) to extended partitions, which would be harder to boot from. – Flexo Aug 12 '15 at 7:17
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but 3 Primary partitions and I should be able to do that.

Nope.

On harddisks with MBR formatting the system was designed to allow up to 4 partitions. You can not add a fifth partition. There simply is no space for more than 4 entries in the defined data structures on disk.

At the time that was plenty. Then disks shrunk and grew. (shrunk as in size. See this nice picture to get an idea how big they were). Grew as in: capacity increased. Suddenly it was viable (and useful!) to chop the disk into smaller part, much like putting multiple stories in a book.

However there is only room in this books index for up to 4 chapters. No more.

This is why you can not add a fifth primary partition.

There is a workaround. A extended partition. Basically it is as if you put in a chapter and devide that into little stories (logical partitions).

This allows you to use more partitions in total, but you can still only have four of those in the original index. So a max of:

  • Up to 4 primaries
  • or up to 3 primaries and an extended partition.
  • (Not supported but found working in the past): 2 primaries, 2 extended partitions.

In all cases you can put multiple volumes/logical drives/... in the extended partition. But you are still limited in what you can put in the primary part.


Now as I read your case:

You have 4 primary partitions. (system reserved and 3 others).
You reduced one of these primaries in size (still using 4 primaries)
You try to add a fifth and it failed.

Next - You changed on of the primaries partitions to extended and created a logical drive in extended

In 'pictures':

|MBR|  Primary 1 | Primary 2 | Primary 3 |  Primary 4             |

Change one to logical

|MBR|  Primary 1 | Primary 2 | Primary 3 |  EXTENDED              |
                                            110GB partition | free|

If you wish you can add more logical partitions which will be placed inside the EXTENDED partition.

You can not create a fouth primary partition because 4 slots are already in use.

Just for completenss, it is also possible that you action resulted in this:

|MBR|  Primary 1 | Primary 2 | Primary 3 |  EXTENDED        | free|
                                            110GB partition |

In which case you want to grow the extended partition and then create a logical drive in the grown space.

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