Why can't I create a logical partition with `gparted`?

Question

I'm trying to create a logical partition inside an extended partition but gparted doesn't let me do it.

My setup:

• System: Ubuntu 16.04
• Partitioning software: gparted 0.25.0

HDD 1TB

• /dev/sda1: extended partition (covers all the space)
  • /dev/sda6: 32GiB system root partition
  • /dev/sda7: 113GiB data partition
  • /dev/sda5: 664GiB main data partition
  • 114GiB Free space I want to use as new partition, not as a part of sda5
  • /dev/sda8: 8GiB swap

Do I have to umount the system root partition?

Is there a workaround?

Is it just a bug?

Why does this happen?

I don't want to run a live CD/USB just to create a partition.

Yes, I know partition numbers are not ordered, but I'm using UUID anyway so who cares. I also know there are almost 70GB missing. This is because GiB is not equal to GB, and the brands sell HDD with measuring unit of 10^12 bytes instead of 2^40 bytes.

Solution

I solved it. All I've done is letting 1MB gap at each side of the partition and setting align to 'none'.

Still I don't understand why this is necessary.

Comments

[Kamil Maciorowski]

How exactly gparted doesn't let you? Have you tried other tools (like fdisk, gdisk)?

[Kamil Maciorowski]

Please leave this question open (don't accept your own answer), so maybe someone will eventually explain to us what happened. I find it interesting. I have changed the question title and emphasized the "why?" part.

[Falk]

maybe the correct question should be something like: why do logical partitions need a 1MB gap at each side in gparted?

[Admin]

this might have nothing to do with not using live session. from a live usb i had the same problem and solved in the same way.

[Admin]

When do logical partitions happen to need 1MB gap at each side in gparted? on unix.stackexchange

[Kamil Maciorowski]

+1 Although this short answer gives a workaround only and explains nothing, I appreciate it could be a life-saver for someone with similar problem.

[Admin]

How have you found about this trick? --- As it is the answer was short but efficient for me too (after solus linux failing to format and install on that partition; worked after formatting it in gparted as you said). - Only I wasn't able to format from a live usb, until I used those settings. This might have nothing to do with being in live session or not.

[Falk]

@cipricus I had an intuition and tried it out.

[Falk]

Sometimes trying out is easier than read lot's of documentation and sourcecode. On the other hand just tring things can be dangerous.

[Admin]

the possible question that you phrased in a past comment : - unix.stackexchange.com/q/438773/32012