Failed at Allocating Requested Partition In RHEL 7.2 Installation

Host OS : Windows 10 Anniversary
Hard Drives : One SSD labeled C, One HDD labeled D

Scenario : Trying to install RHEL alongside with Windows 10 from a bootable USB with RHEL 7.2 DVD ISO burnt on

Problem: after entering the Anaconda installer, in the installation destination section, if you choose to have an automatically partitioning, it will fail even you have enough extended partition free space on your D disk. If you try to manually partition it, you will fail at creating at most the third mounts point(the mount point such as /home, /var that does not create its own primary partition does not count.).

Solution:

The cause of this problem is because the D disk is probably using the MBR partitioning scheme. Go download the partition manager http://www.easeus.com/partition-manager/epm-free.html (it has a free version, which differs from the free trial version), and check if your D disk is using the MBR. If it is, then the failure of installation is due to the limitation imposed by MBR that the drive using MBR can at most host 4 of primary partitions, and the RHEL installer trying to create more than 4 primary partitions on the disk. Therefore, you can use the Easeus to convert the D disk from using MBR to GPT which supports at most 128 primary partitions on Windows.

Suggestion:
Have the installer perform a partitioning scheme check when selecting the installation destination, if MBR detected then warning the user that the slots for primary partitions might not be enough for installing RHEL.