but 3 Primary partitions and I should be able to do that.
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.
- You changed on of the primaries partitions to extended and created a logical drive in extended
|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.