Virtually Virtual Virtualisation

Virtualisation is becoming a buzz-word all over the world for those of us required to design and implement new infrastructures.

What tools are there, and what should we know, or care about them?


VMWare is not free. True, there is a VMWare Player with which you can install and run pre-built virtual machines. VMWare Virtual Server is free. But there is no support and it has serious limitations.

VMWare also have a workstation virtual host, VMWare Workstation. It is capable of hosting both Linux and Windows guests. Along with this virtual host there is VMWare ACE. This utility provides security for ‘unmanaged’ workstations. It packages a virtual workstation in a ‘lock-down’ mode and deploys it to another workstation and will securely manage that PC. VMWare claim that this enables us to secure network end-points.

VMWare ESX Virtual Server is simply a Linux distribution with a modified kernel. At boot-up you even have the choice of booting the virtual host or a full installation of Linux. Why Linux? Because Microsoft will not allow the modification of it’s kernel and, some of us might say that Windows is not exactly a resilient platform.

VMWare and Microsoft have a competitive relationship, that’s probably another reason why no Windows based development has occurred. This product has a high price tag, and is licensed per CPU. The ongoing support costs are also based on the number of CPUs.

ESX Server is the premier virtualisation product from VMWare. It can be installed directly on the metal and you can manage it remotely using the Management Console (a browser interface) or from VirtualCenter, (which you have to purchase and requires both a server and agent license per installation), which contains a few tools, such as VMotion (using VMotion you can drag and drop virtual servers from place to place). To provide resilience you will have to purchase VMWare High Availability.

Those of us who are regular open-source ‘Heartbeat’ users, will recognise this utility. VMWare have created a GUI for it, but it’s functionality is pure ‘Heartbeat’.

VMWare P2V (Assistant). P2V will create an image of a server installation (an on-the-metal install) and deploy it in a virtual guest machine. VMWare P2V, is not free, and there is an ongoing licensing per image. That can make it too costly for smaller enterprises to deploy. It can save you time, that’s about all.

If you would like to have all these in one go, guess what? VMWare has created VMWare Infrastructure.

Microsoft Virtual Server

Microsoft bought part of Connectix and that part was the virtual toolset. From that Microsoft developed the current Virtual Server.

This virtual server is becoming more popular. Why? Because Microsoft now offers it as a free tool. Why did it do that? Because the competition from VMWare was killing it’s market share. By making it free and offering support, Microsoft guaranteed it’s product a market share. But it is far behind VMWare and shows no signs of catching up.

Microsoft Virtual Server does not have the array of added value tools and utilities that VMWare has so cleverly identified and created. It is, surprisingly, a Linux kernel. It cannot be installed directly on the metal. Couple that with the fact that it must be hosted by a version of Windows server, and you can see that it does have some serious shortcomings.

Microsoft will kill off this product in the very near future. Because the plan is to modify the Windows kernel and implement a Hypervisor in Longhorn. There will be no need to have a separate virtual server if a Hypervisor becomes a standard part of the Windows architecture. In the meantime Microsoft Virtual Server is being marketed as a comfortable means to deploy multiple virtual Windows servers, and is aimed at the Wintel folk who tend to be bit wary of Linux, and are addicted to the Win’95 desktop.

I said that Microsoft will include a Hypervisor in Longhorn. That may not happen. Microsoft has just signed a deal with XenSource, this deal provides Microsoft with the most important feature that it currently does not have, an on-the-metal virtual server. Right now, you have to have a fully installed Windows Server to implement Microsoft’s Virtual Server product. This makes Microsoft’s product vulnerable to some criticisms. That anything on a Windows operating system has a very short life span and is a vulnerable, high-profile target for the bad-guys. Windows servers MUST be rebooted occasionally to sort out performance issues, this has always been the case and remains so. We have come to accept that fact and learned to live with it. But, if you have to reboot a host server, all the virtual servers have to be rebooted too! Windows is full of ‘holes’, and the ever-increasing patches, and upgrades, demands large areas of disk-space and other systems for their deployment, plus the additional costs of management. As soon as you host virtual servers on this type of platform you are creating a very high-risk, single-point-of-failure that will effect not just the host server, but all of the virtual servers on the box and everything connected to it.

Until recently a Microsoft Virtual Server would not host a Linux operating system. That is now not the case. In fact, not only can you host Linux, but Microsoft will support it; on a free product too. Now that’s what I call service.

Microsoft is at least three years behind VMWare in terms of advanced virtualisation technologies. It is true that the Microsoft Virtual Hard Disk File format has been licensed to XenSource. An unusual tactic for a company like Microsoft. But it’s a cute move because it enables XenSource to produce a HyperVisor that will enable both Linux and Windows virtual servers to be moved independently between both Linux and Windows hosts, and will be hardware agnostic. VMWare’s Virtual Server Disk File format has just been presented to the industry as free open-code. VMWare has done this to extend their advantage over Microsoft. Now developers of added value products can start to develop tools and utilities to further advance VMWare virtual servers.

Microsoft’s current virtual server product is handicapped by the fact that it has no Hypervisor. It could be several years, (some reports say up to ten years), before Microsoft has an integrated Hypervisor in it’s server operating systems. Until then, users are migrating to VMWare, or are ignoring Microsoft Virtual Server because of it’s lack of resilience, need for a host operating system, slowness, and short business future. Be aware of this before you plan to deploy Microsoft Virtual Server. You might be comfortable with Windows, but your client may not be too pleased when you have to report that the product is deprecated and it’s time to migrate the infrastructure to VMWare or XEN.


XenSource is developing a product named XENEnterprise. Originally, this product was aimed at taking market share from Microsoft. But because the recent deal between XenSource and Microsoft stymies that approach, XENEnterprise is now to be a ‘unique’ product which will enable users to host Linux, Solaris, (possibly) Macs, and Windows servers on a single Hypervisor. Phew!

XENEnterprise is not free. I don’t know the price yet. But, presumably, it will be competitive with the competition. The key to this product is the ability to deploy it in any infrastructure and use it to host ‘any’ operating system. This is called “Appropriate Virtual Deployment” (well, that’s my invention but you have to admit it sounds pretty cool), and will please users and customers. Why? Because it short-circuits the Wintel folk’s fears, and objections to Linux. Given that the majority of servers deployed in enterprise infrastructures are Windows based, this will enable those enterprises to take advantage of Linux attributes, such as security, stability, high availability and so forth, and still have that good-‘ole Win’95 desktop shining from every rack. One of the biggest advantages will be around the lowering of licenses when the hardware is multi-core CPUs. But that’s another article.

XENEnterprise has another big advantage over VMWare and Microsoft virtual offerings. ParaVirtualisation.

ParaVirtualisation enables near on-the-metal performance. There is no latency issue, it handles memory as a standard installation and it provides up to 30% overhead advantage when compared to it’s commercial rivals. It also includes, as standard, P2V tools. Add to this it’s exploitation of the processor virtualisation extensions now provided by both AMD and Intel, and you have the product of the future right now.

XENEnterprise is new. That presents a risk. When planning your virtual environment you cannot ignore this product, but, it’s a good idea to look carefully at whether or not you and your customer are prepared to accept the current risk, and if the other commercial products might present a safer Appropriate Virtual Deployment (sorry, couldn’t resist it).


Not the most well known of the virtualisation tools. But it does do what it says on the box. It differs in it’s methodology to the other offerings. Instead of virtualising at the hardware level, Virtuozzo virtualises at the operating system level. It provides multiple secure and isolated environments/operating systems on top of a single host kernel. The kernel is Linux, by the way. One upside is that because the Virtual Environments (VE) are at the o/s level, there is less overhead required to run the whole system than, say, VMWare or Microsoft Virtual Server.

Each VE has its own file system, memory, network devices, user and groups etc. Each is isolated from it’s virtual neighbours and can belong to entirely different network systems. High numbers of VEs can be created on a single host. Virtuozzo partitions the host operating system into as many VEs as required. One of the claims made about Virtuozzo is that it contains virtual sprawl. Hmm, not sure about that. With potentially hundreds of VEs per host, my thinking is that you could, inadvertently, create multiple sprawls on each box. Added together, this would equal a migraine for administration and management.

One of Virtuozzo’s coolest features is the ability to distribute applications across VEs. They can ‘load balance’ the application and decide which VE is best suited at any particular time to provide processing power for the application. This is called ‘Server Agility’. It’s very useful where it is necessary to co-host applications and services within a consolidated infrastructure. The system figures out which VEs are under-utilised and will use them to run the applications.

Virtuozzo claim to remove the problem of provisioning. Instead of having to calculate your provision of servers over three to five years, you just don’t bother. When you need more servers to host more applications or provide more services, you just knock up a few more VEs. Job done!

Virtuozzo comes complete with all the necessary management tools. It’s pretty much OOBE as it should be.

There are tools for moving VEs across different Virtuozzo servers in the event of a disaster. A SAN is not really required (which must be a big plus). That reduces costs tremendously and Virtuozzo claim that you can move live applications while data is in transit (“up to the last moment”).

Virtuozzo made it’s bones in the Service Provider sector, and is still highly utilised in American ISPs and other service provider infrastructures. Virtuozzo offers a bunch of products built on it’s core virtualisation product:


Virtual Infrastructure


Managed VE

Dynamic Servers

All these, and more, are offered to the Service Provider market. You can find out more by visiting their web site

I don’t know why this product has not taken off in the UK to the same extent it has in the USA. I specified it for a call centre, in my life before Fujitsu, but the top-gun turned it down. No tangible reason was given, other than it was ‘strange and risky’. Well, probably. But, time has moved on and this product does have some very interesting advantages, particularly for hosting and applications.

Virtuozzo supports Windows and Linux, so you Microsoft fans can relax. In fact, Virtuozzo should be very interesting for Windows people as it will install on 32bit and 64bit Windows, and will guest 32bit and 64bit Windows. Good platform/environment for Exchange, particularly when using “Server Agility”. And, it will do all of this on a P3 with a gig of RAM (minimum spec’). That is certainly going to make it attractive to those of us with little spare cash and older kit.

Because Virtuozzo sits on top of the operating system, it supports all the hardware that both Linux and Windows support. This cannot be said of the other virtualisation products. They are a little more choosy when it comes to the ironware.


XEN was developed by a bunch of British ‘cheps and chepettes’ at Cambridge Uni’. They are still working with XEN, but have now launched XENEnterprise.

XEN is a Hypervisor. It is implemented from within a Linux operating system. You install SuSE or Red Hat (must be the Enterprise versions and no earlier than the latest releases), and after the installation you can choose to recompile the kernel to include the XEN extensions/code.

XEN has a very small footprint. It is under 60,000 lines of code. It’s a lean, mean virtual machine, and it is, probably, the best of all the virtual hosts currently available. I say this because it offers ParaVirtualisation, simple installation, near metal performance, and equals the low overhead of XENEnterprise. In fact, some figures show that it is more efficient than XENEnterprise.

Currently, XEN does not support Windows guests out of the box. But, if you install it on hardware that has the virtual extensions (AMD V and Intel VT) it will support Windows server guests. The failing is not XEN’s, it’s because of the way that Windows addresses the hardware. So, it’s Microsoft’s fault!

The biggest advantage that XEN has over all the others, is the simple fact that it is FREE. You get all of the advantages of all of the other virtualisation products, without the problems, and limitations of Microsoft, or the high costs associated with VMWare.

When installed, XEN runs completely invisibly. You can use it you want to. If you don’t it makes no difference to your host installation. It does not require any special browser extensions and you can manage it with VNC, SSH, or a third-party product such as the excellent NXMachine (go to to find out more about the NXMachine terminal server products). XEN truly is the best of the best. I use it everyday. I have my web servers hosted on two DL385s running SuSE Enterprise 10 as XEN. I can categorically state that installation, configuration and management really is very simple. So simple, in fact, that my dog can do it. Now that has to be a plus.

I can’t find any downside to XEN. If you can, maybe you might like to let me know what it is.

So, what can you do with XEN? Pretty much anything you can do with the other virtualisation tools. Plus you can run the host operating system in parallel. You can do that with Microsoft Virtual Server, but you would be a very brave person to do it, in my opinion.

XEN can also take advantage of the free Heartbeat that comes with SuSE and Red Hat Enterprise operating systems. It is basically a packaged HALinux. You edit three text files and forget about it. Yes, there is now a GUI for you point ‘n’ click folks. It doesn’t require a degree to install and manage. There is no management as such. Heartbeat monitors the clustered nodes and fails over instantly. In it’s simplest configuration all you need is an extra NIC for each VS and a crossover CAT cable for the hardware nodes. You don’t need expensive and unnecessary fibre connections, you don’t need intelligent switches or all that other techie ironware that has crept into the server-room. It’s simple, and it works.

Parallels Desktop For MAC

Parallels Desktop For MACS is a virtual tool that has Hypervisor technology built into the host system.

It supports The entire Windows family, right up to XP and 2003, Linux distributions like Red Hat, SuSE, Mandriva, Debian and Fedora Core, FreeBSD, and “Legacy” operating systems like OS/2, eComStation and MS-DOS. The latest release adds Solaris to it’s supported guest operating system list.

Parallels Desktop for Mac is the first solution that gives Apple users the ability to run Windows, Linux or any other operating system and their critical applications at the same time as Mac OS X on Intel-powered iMac, Mac Mini, MacBook or MacBook Pro.

Unlike dual-boot solutions, in which users must completely shut down Mac OS X and endure a full OS start-up cycle to access a important application, Parallels Desktop for Mac empowers users with the ability to run important Windows programs like Outlook, Access, Internet Explorer and all other applications without having to give up the usability and functionality of their Mac OS X machine even for a few minutes.

Very neat little tool for our Apple Mac brothers and sisters. It retails at £30 per license.


Clearly virtualisation is here to stay. In fact, it never left. Virtualisation technologies date from the 1960s. Hypervisors were developed at that time. As with all things IT, what goes around, comes around. IBM, which pioneered virtualisation back in the 1960’s for its mainframe systems, also punched its ticket to ride the XEN train. They announced recently that the company would support XEN on its server and blade platforms that run on Intel and AMD processors, and that its middleware will also support the virtualisation technology.

IBM is not the only vendor to make this kind of decision. All other hardware vendors are on the virtualisation wagon. That’s good news for us. Because we have vendor choice.

AMD and Intel clearly have their sights on the virtualisation race and have provided some excellent advantages within their processor ranges. We can now run Windows on Linux, Linux on Windows, Linux on Linux, and Windows on Windows. Not only that, we can drag and drop fully functioning servers from one location to another. Not only from one host to another, but from one town, or city, or country to another. That has incredible implications for Disaster Recovery and Business Continuity.

Beyond all this, there is another area of virtualisation that is beginning to shift gears. Virtual Storage, or Storage Virtualisation.

For years vendors such as EMC, Network Appliance, and others have offered storage virtualisation at the disk-array or hardware level, whereas software companies such as Veritas have offered virtualisation at the host level. More recently, a number of vendors such as StorageApps, DataCore, XIOtech, FalconStor, and StoreAge have arrived offering storage virtualisation at the network level, many in the form of storage appliances.

What this all means to us is confusion, sorry, choice. But, because these vendors are all keen to make us use their products, we must make sure that we fully understand the technologies to avoid being seduced into using a non-appropriate product. My next article may well be all about Virtual Storage, who knows.

One final word of warning about virtualisation. It is NOT the answer to all problems. Even consolidation may not benefit from virtualisation. Use it where appropriate. And remember, if you over-use it you will replace the hardware sprawl with virtual sprawl, and your management problems will be the same.

Related Articles

Back to top button