I attempted to install CentOS 7 x86_64 on my machine that has the following hardware:

Motherboard:      ASRock X99 Taichi BIOS:             AMI v P1.40  08/04/2016 CPU:              Intel Core I7-5820K RAM:              64 GB (8 x 8 GB DIMM) Optical:          LG Blu Ray 25 G / 50 G burner Storage:          2 - 120GB   PNY CS1311 SSD  4 - 4 TB Western Digital hard drives                   The 2 SSD drives are divided into 3 software RAID-1 devices:                       /dev/sda1 | /dev/sdb1 = /dev/md0 (2 GB)                           /dev/md0                     /boot                       /dev/sda2 | /dev/sdb2 = /dev/md1 (77 GB) LVM /dev/VG_opsys                           /dev/vg_opsys/lv_root        / 8 GB                           /dev/vg_opsys/lv_archive     /archive 2 GB                           /dev/vg_opsys/lv_opt         /opt 2 GB                           /dev/vg_opsys/lv_tmp         /tmp 5 GB                           /dev/vg_opsys/lv_usr         /usr 12 GB                           /dev/vg_opsys/lv_usr_local   /usr/local 2 GB                           /dev/vg_opsys/lv_var         /var 8 GB                       /dev/sda3 | /dev/sdb3 = /dev/md2 (32 GB) LVM /dev/vg_sysswap                           /dev/vg_sysswap/lv_sysswap   swap 16 GB                   4 - 4 TB Western Digital hard drives                   The 4 WD drives are divided into a single software RAID-10 device:                       /sdc1 | /sdd1 | /sde1 | /sdf1 = /dev/md3 (7.28 TB) LVM /dev/vg_jpd1data                           /dev/vg_jpd1data/lv_dbmsu00 /dbmsu00      160 GB                           /dev/vg_jpd1data/lv_websoft /websoft      70 GB                                   ...  ETC   ...

I like this configuration so I thought ...

Installation attempt 1: Machine had been running CentOS 6.10 x86_64 with no problems at all. But I wanted to do some things on this machine and I didn't want to have to do a upgrade next year. I backed up all of the data on another machine so I wouldn't suffer a data loss. Inserted the CentOS 7 DVD and rebooted - for whatever reason it didn't see the DVD.

Installation attempt 2: Rebooted and selected F11 for the boot menu and selected the SATA device for the Blu Ray (BTW, there was another selection that allowed me to boot UEFI for the Blu Ray). The installation continued and when I got the the storage screen I selected all 6 storage devices. When I got to the point where I tried to select all of the file systems (BTW, the /boot device was listed as unknown) I wanted format the volumes /boot, OpSys, and swap and I wanted to just mount the devices defined on the RAID-10 device. When I tried to accept the definitions the install just hung at the point. I had to power off the machine.

Installation attempt 3: I decided to start from scratch so I went into rescue mode and removed all of the partitions on all 6 disks. So when I got the the storage screen I only selected the 2 120GB disks and went through a complete definition for /boot, vg_opsys, and vg_sysswap.  But once again when I got to the point where I had to accept what was to be formatted it hung and had to be powered off t restart the install.

I thought it might be my DVD so I downloaded a minimal install to try again.

Installation attempt 4. I remembered that there are instructions on how to add software raid-1 on a running machine. So I did the allocations on a single 120 GB drive (/dev/sda). When I got to the same point as the first 3 attempts it once again hung.

I rebooted on my GParted DVD and removed all the partitions on all 6 drives. Then rebooted using the CentOS 6 DVD and did the complete install including the RAID-10 devices.

Why could I install completely CentOS 6 but not CentOS 7?

Note:   When booting I saw a selection for PF2 so I could setup UEFI. Also PF11 allows me to make a         choice to boot from SATA3 standard MBR or UEFI boot.

What am I doing wrong?