Not an IT person.
But I work with IT / Software.
Not an On-Premise, Legacy Software Person.
But I work with On-Premise Software now.
A question I eavesdrop today:
Does the DR needs another set of licensing?
Based on my boss, there’s a need for two sets license.
I began my research, and to find proof to this answer.
This post, has not talk about the licensing, licensing come later. Before we go to licensing, we need to know virtualization.
A few terms that’s very ‘popular’ for virtualization:
- Hypervisor Source
A hypervisor, also called a virtual machine manager, is a program that allows multiple operating systems to share a single hardware host. Each operating system appears to have the host’s processor, memory, and other resources all to itself.
- VM – Virtual Machine Source
A virtual machine runs a dedicated operating system on shared physical hardware resources. VMs increase hardware utilization, but there are risks.
- vmware Source
VMware, Inc. is a subsidiary of Dell EMC, a division of Dell Technologies, that provides cloud and virtualization software and services, and claims to be the first to successfully virtualize the x86 architecture commercially.
The X86 compatible hardware of today, regardless of processor count or core count, was designed to run a single operating system.
These are very very brief result, however, it has successfully picture the difference among hardware, software, and management.
(1) we bought a server – the blue box – Intel 6Core Server with 32GB RAM, sounds good?
As of all x86 servers (most common type), we can install 1 Operating System (OS). Therefore – in this case, Windows Server 2012.
(2) someone came into the picture, introduces vmware (just an example, not selling), this software allow us to install second server in the same box we bought.
(2a) we can split the box into 2 (logically), maintain Windows Server 2012, and install a Linux Server.
(2b) we can split the box into 3 (logically), maintain Windows Server 2012, install another 2 servers, e.g. Linux, Solaris.
Yes, Linux has Operating System for Server, sames goes to Solaris. These names are not common, but they appear on top 5 server OS. Source
Now these servers that we installed into the box, we call them VM, virtual machines.
We cannot tell from the box that there are 3 servers, because, this “split” is achieved using software virtualization.
Alright, now you have these multiple OS in a box = you have 3 VMs, how are you going to manage them?
How to manage the installation of application, the processing power, etc?
That’s how Hypervisor come into play.
Hypervisor is a virtual machine monitor (hyper-supervisor, haha)
It monitor the VMs, offer management and many other benefits.
(3) The Hypervisor is installed in the box, to enable management of the virtual machines.
This site gives a good, layman explanation to VM, found out more:
Installation of the hypervisor, VMs does not follow my flow chart, it is only giving you an idea of how these component work together.
The risk of having 1 physical server with 3 VMs is not explained, but remember – if the box is burnt, same goes to 3 VMs.
There comes my next topic: Redundancy, Disaster Recovery.