[GTALUG] Setting up a VM host

[Alvin Starr]

On 08/29/2016 10:07 AM, Lennart Sorensen via talk wrote:
> On Fri, Aug 26, 2016 at 09:33:50PM -0400, William Park via talk wrote:
>> - QEMU and VirtualBox.  They both use KVM.
> Virtualbox does not use kvm.  It will use vt-x if you have it.
> kvm requires it.
Its kind of the other way around.
Virtualbox uses QEMU as does Xen and I am sure it appears in some form 
with other virtualization platforms.
QEMU is the go-to source for hardware emulation.

>
>> - VirtualBox practically needs no manual.  It's all mouse clicks.  The
>>    only time I actually had to read something, was to convert VMDK to VDI
>>    format (using VBoxManage on command line in Windows)
>> - QEMU requires manpage and shell script to store all the options you
>>    discovered. :-)
> But the flexibility is great.
Virtual-box is more akin to libvirt in that its a hypervisor management 
tool.

Virtual-box gives a lot of flexibility if you want dig under the covers 
and use the command line interface.
But its ugly.
Libvirt has the advantage that it will interface with multiple back-end 
hypervisors.

Using QEMU directly gives more flexibility because you have to manage 
most of the system plumbing tasks on your own.
Virtual-box and libvirt help you manage those tasks but  make some 
implementation choices that you may or may not like.


>
>> I'm not sure about "headless".  From memory, I seems to have closer
>> association with VirtualBox than with QEMU.
> qemu's ability to run as a vnc server is handy.
>
I know libvirt allows for a serial console so that there is no need for 
a graphical and I have used that quite a bit because I often found 
myself at the end of a low bandwidth connection where running VNC was 
just too painful to be believed.
I am sure Virtual-box has the same feature but I have never used it.

In general Virtual-box is easier to install and works well for running 
up a hand full of virtual machines.
Virtual-box seems to make better default choices for performance and 
gives better emulation of things like USB interfaces.
It also does a reasonable job at simple network plumbing and importing 
and exporting of disk images.

Virtual-manager is somewhat like Vritual-box and is part of the libvirt 
suite of tools.
It is more generic and allows you to manage several virtualization 
servers along with different hypervisors.
It does a reasonable job at network plumbing but its hardware emulation 
is only as good as the mainline QEMU support, and the Oracle folks are 
able to pay to get access to proprietary information about hardware 
making their emulation a bit better.
The libvirt development tends to track the KVM/QEMU develpment so just 
about every feature that is available directly in QEMU can be found in 
libvirt.

The above tools are good for straight forward flat networks but if you 
require complex network plumbing like NAT interfaces and simple 
firewalls and multiple isolated networks then your are getting out of 
the range of the simple virtualization managers and are looking more at 
something like Openstack and its competitors.

-- 

Alvin Starr                   ||   voice: (905)513-7688
Netvel Inc.                   ||   Cell:  (416)806-0133
alvin at netvel.net              ||

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