How to install Ubuntu 14.04.3 as a virtual OS (kvm)?

Question

LVM

There is an Intel Core i5 system, 2 * 2TB, 8GB of RAM.
Hosters installed Ubuntu 14.04.3 LTS, raid1+lvm.

$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb1[1] sda1[0]
      1953382208 blocks super 1.2 [2/2] [UU]

unused devices: <none>unused devices: <none>

Installed kvm+libvirt-bin under webvirtmgr .
When installing Ubuntu 14.04.3-server amd64 (latest from offsite), at the very beginning, the message
unable to mount /dev/vda
umount /dev/vda
..
Next, at the disk partitioning step, the process freezes (blank purple screen).
Moreover, when installing 12.04 LTS, everything is in order. When installing 14.04.2/3, 15.04 the problem.
Probably a problem with lvm+grub. I'm not very advanced (
Who faced the problem?
Thank you.

Answer 1

I installed the guest system through the console using virt-install, everything worked. And then you can manage through WebvirtMgr.
Later I found out that in the Webvirtmgr panel, when creating a new guest system, you need to uncheck the "Host-Model" checkbox and everything works.
As far as I understand, with this option, the hardware parameters in the guest system will correspond to the host system, i.e. the virtual machine will adapt as much as possible to the host machine for speed. If you try to transfer it to another host server with different hardware, it may not start.
Without this option, the guest system can be easily transferred to another host server, regardless of the hardware.
I was satisfied with the second option and stopped there. I did not look for the exact cause of the problem due to lack of time.