Virtual Servers Guidance

Daff_Duck · 9 Feb 2015 at 21:54

Virtual Servers have just started to be deployed in my organization, Most of the Virtual servers are running Server 2012 along with clinical software etc on separate Virtual OS? And whilst I understand the basic concept of these. I wonder if anyone has come across an informative web link that explains what software can be put on these. I appreciate that you can have multiple virtual disks with different software on each on a single solid state server.

My aim is to understand the concept a bit more in order to improve my knowledge and basically get to grips with the basics in order to identify simple things that may or may not go wrong. Plus not to look a tool when someone talks to me about them.

If anyone would good enough to advise I would grateful.

blueboy2001 · 10 Feb 2015 at 02:21

http://www.vmware.com/pdf/virtualization.pdf

Basically you run a small Operating System called a Hypervisor on the physical server - VMWare ESXi for example. The Hypervisor acts an interface between the physical hardware and the virtual machines.

The Virtual machine exists as a configuration file and a number of virtual disk files. You can copy these to another machine running the same hypervisor and load the VM up.

Usually you would use some sort of shared storage and multiple physical servers running hypervisors to give you fault tolerance. With products like VMWare VSphere, you can move a VM between physical servers seamlessly with it up and running (VMotion).

Inside the virtual machine, it's no different to a physical machine really. You can run exactly the same software.

If you've got a decent PC download a copy of VMWare Player and some free OS's and have a play installing them. VMWare Player is not a hypervisor per-se, but it allows you to run virtual machines on your PC. The principles are largely the same.

BlizzardX · 10 Feb 2015 at 03:02

The key difference is to understand Type 1 and 2 hypervisors. Type 1 are the baremetal, VMWare ESXi, Xen, Hyper-V Server etc. These ones act as Blueboy has described.

Type 2 are essentially full blown OS's with a hypervisor running within them, i.e. KVM, Server 2012 with Hyper-V role, VMWare Workstation... These are not as efficient as Type 1 as they cannot share the hardware as effectively.

El Pew · 10 Feb 2015 at 09:06

BlizzardX said:
Server 2012 with Hyper-V role

Is this technically a Type 2? The way I understand it, the OS basically turns itself inside out and performs a P2V on itself, so the base OS just becomes another VM.

RichIbizaSport · 10 Feb 2015 at 10:56

El Pew said:
Is this technically a Type 2? The way I understand it, the OS basically turns itself inside out and performs a P2V on itself, so the base OS just becomes another VM.

Yes it's a type 2. You have a Windows server 2012 server, you install the hyper-v role. The base OS is still bare metal but you have the option to create virtual machines.

El Pew · 10 Feb 2015 at 11:44

RichIbizaSport said:
Yes it's a type 2. You have a Windows server 2012 server, you install the hyper-v role. The base OS is still bare metal but you have the option to create virtual machines.

I looked into this, and you're incorrect. The Hyper-V role is Type 1, not Type 2. The hypervisor sits on the bare metal and the previously installed Windows OS becomes a VM within that hypervisor:

Hyper-V installs in much the same way. It lifts the base operating system up off the bare-metal, injects the thin-layer hypervisor onto the bare-metal hardware, and instead of placing the original back where it was, it condenses it into what I call a para-virtual machine, and creates the Parent Partition, which is a concept unique to Microsoft.

http://garvis.ca/2012/01/03/layer-1...-a-brief-explanation-of-the-parent-partition/

BlizzardX · 10 Feb 2015 at 19:03

El Pew said:
I looked into this, and you're incorrect. The Hyper-V role is Type 1, not Type 2. The hypervisor sits on the bare metal and the previously installed Windows OS becomes a VM within that hypervisor:

http://garvis.ca/2012/01/03/layer-1...-a-brief-explanation-of-the-parent-partition/

I'm surprised, although I haven't used hyper-v extensively... I use xenserver on my homelab instead... So it elevates the default install to a Dom0 entity? When I did run S2012R2 with Hyper-V, it seemed like a normal OS and I was unable to over provision the hardware within the running os like you can on ESXi and Xen. I can't imagine it will be as efficient as a bare metal installed Hypervisor though.

Caged · 10 Feb 2015 at 20:29

It is a bare-metal hypervisor and has been since Server 2008. It's virtualising the originally installed Windows Server inside itself. Performance deltas between ESXi and Hyper-V are in the margin of error.

RichIbizaSport · 10 Feb 2015 at 23:51

Wow, it would seem tis true. I can't quite believe that's what happens with the role, seems a bit bizarre to be honest. I wonder what their reasoning is.

I stick to Hyper-v server myself!

BlizzardX · 11 Feb 2015 at 01:00

Caged said:
It is a bare-metal hypervisor and has been since Server 2008. It's virtualising the originally installed Windows Server inside itself. Performance deltas between ESXi and Hyper-V are in the margin of error.

Well that is cool then, are you able to adjust the number of vcpu, memory allocated to this virtualised server as I couldn't see it in the hyper-v manager?