Introduction to Virtualisation
In the current IT market the most commonly used type of virtualisation is known as “Server Virtualisation”. Server Virtualisation allows you to run multiple OSs on 1 physical host, this leads to a saving on items such as network components, UPS, update time etc.
When starting off in virtualisation you can use products such as MS Virtual server or VMware workstation/server. In a production data centre you will use products such as ESX V-sphere, MS Hyper-V or Citrix Zen.
The difference between the 2 approaches highlighted above is that one is run within an OS and the other is installed directly onto host. These are commonly known as:
- Virtualized Management Layer approach (“hosted”).
- Dedicated Virtualized approach.
Other types of virtualisations that are currently available are:
Allows removing physical mappings between the HW and the storage and moving the storage into logical objects. The logical components allow the administrator to gain benefits such as ease of data migration and lower cost of storage. Datacore SanSymphony is a good example of storage virtualisation.
Split into internal and external.
Allows, a user, to run 2 instances of 1 application on a single host. For example it will give the ability to run outlook 2003 and outlook 2007 on the same host.
The products on the market that allow this are:
- VM ThinApp.
- XenApp by Citrix.
- MS Softgrid.
They allow this by running a virtual OS, registry and File system where the application will sit on. The users will then access the application via streaming from another location. The application can be accessed locally or over the network on virtually any device.
Hosts such as laptops, PCs or Thin Clients are used to access virtual desktops in the Virtual Environment via a broker (VMware view manager). The software which allows us to achieve this is called VDI (Virtual Desktop Infrastructure). The physical hosts will access the broker via TCP/IP connections at all times.
In this section we covered all the types of virtualisations currently available on the market. These types of virtualisations can help to gain the following benefits:
- Consolidate servers which currently run legacy applications.
- Much more efficient use of HW.
- Fewer physical points of admin.
- Less maintenance costs.
- High availability and load balancing.
- Easier testing and development by making use of Point in Time snapshots.
- Network isolation from production environment which can be useful for testing and troubleshooting.
- Easier DR by migrating applications between hosts and OS.