Advice from Alan Richards, West Hatch High School. Words taken from the Virtualisation with Microsoft® Hyper-V eBook.
“Fail to prepare… prepare to fail.” – That’s very much the mindset that’s needed by an organisation embarking on server virtualisation.
The planning phase is vital and demands serious attention. It can’t he overlooked, hurried or entered into lightly. Information technology is core to any business from high street banks to the smallest of primary schools. Should it fail, or is not fit for purpose, then the business could fail. In a school or college that means failing the very people we are all here for – the students.
Should you run a trial?
Part of being meticulous about planning means you should think about running a trial ahead of full implementation. At West Hatch High School we ran a year long trial. Virtualisation was still quite new to schools and I believed it had to prove its worth.
Virtualisation is now much more proven. So you may be happy to miss out the trial, and settle for researching what other people have done, and pulling together all of the information available in blogs, white papers and videos. I believe, though, that a trial’s still advisable. It may well save time and trouble later on by providing details about your network and how your infrastructure can cope with the demands of virtualisation.
How you run the trial will depend on the information you want to discover, and to a certain extent, how much money you want to spend on the hardware.
The purpose of your trial
A simple trial would consist of a single server with enough on board storage to cope with 3 or 4 virtual servers, and network connectivity to service the virtual servers. This type of test will allow you to monitor the loads on your network infrastructure, the actual network cards on the servers, and also allow you to monitor the end user experience.
If you have already decided on virtualisation and your trial is going to be used to simply collect data to help in the planning and installation phases, then you could go for a trial setup with a single server and the storage system of your choice.
This setup will allow you to collect all the required data but also make the transition to a full virtualised environment a lot easier.
Whichever method of trial you decide on, the data collected will never go to waste as it can be used to inform your decision making throughout the process of virtualisation.
Know your starting point
Do the groundwork. Begin by finding out what what’s already in place and how it is being used. Before you can plan for how many virtual hosts, you need you need to know what servers you are going to virtualise and the load that they are under currently. The load on servers is an important factor in deciding on your virtualisation strategy. For instance, it would not be advisable to place all your memory-hungry servers on the same virtual host.
Finding out what you have can include:
- A simple list of servers
- Disk utilisation monitoring
- Network monitoring tools to map out the network load and utilisation
- CPU load
All of these factors will help you to answer some of the key questions, which can include:
- How many virtual hosts do I need
- What size storage should I purchase
- What type of storage (iSCSI, fibre channel etc.)
Having full and accurate answers to these questions will be decisive in determining how well your virtualised environment performs.
What to virtualise
A major question you will have to ask yourself is what services you are going to virtualise. Theoretically you can virtualise any server,
Windows® based or not. But just how far you go – whether you should virtualise everything, for example, simply because you can – is a question that has produced some very heated debates in the IT community.
Take, for example, Active Directory, one of the core services in any Windows based domain. At its most basic level, it provides the logon functionality for users to access computers and therefore their network accounts. If this service fails, the network is fundamentally compromised, so one argument says that by virtualising it you are providing a level of fault tolerance because it isn’t a physical server. However, the downside here is to consider what happens if you’re virtual hosts are members of the domain and your virtualised domain controller fails. How do you log into your host if it requires a domain account to login?
Obviously this is an extreme case, and there are ways around it. As a rule it is best practice to keep at least one physical domain controller to provide active directory functionality. You can then have as many virtualised domain controllers as you like for
The general point we’re making here, though, is that you need to weigh up carefully all the issues around what services you might virtualise.
Other considerations that might arise include:
- Physical connection. For example there is no way to connect to external SCSI connections in Hyper-V, such as tape drives
- Security, both physical and logical (is it, for example, a company requirement to have your root certificate authority server locked away somewhere secure?)
Microsoft® Assessment & Planning Toolkit
While there is no substitute for ‘knowing your network’ there is a tool provided by Microsoft that will make life slightly easier for you. The Microsoft Assessment & Planning (MAP) toolkit will look at your current servers and provide you with suggested setups for your virtualised environment.
But don’t take the solutions it comes up with as definitive answers. Regard them as helpful starting points for your own planning.
You can download the tool for free from the Download Centre.
Virtualisation with Microsoft® Hyper-V eBook
This post has been taken from our Virtualisation with Microsoft Hyper-V eBook. View/Download the full eBook below: