Your small business might have started out with a peer-to-peer network, but as it grew to have more than 10 or 15 workstations, you probably found the workgroup security model became more difficult to manage.
A company with more than a handful of employees needs centralized storage for data, and as security issues become more important (as they usually do as the business grows), you also need more centralized control over the systems on the network.
Moving to the client-server model
Your next step was probably to set up a single server. To gain advanced security and administrative features, you may have implemented a Windows domain, with "the" server acting as domain controller, file server, print server, name resolution server and any other server roles you might have.
The SBS single-server approach
One approach to the single server model is to use software targeted at small businesses such as Microsoft's Small Business Server (SBS). SBS 2003 lets you implement an Exchange e-mail server, an Internet Information Services (IIS) Web server, Windows SharePoint services for team collaboration, and a shared fax service, all built on the Windows Server 2003 operating system and installed on a single physical machine.
The Premium Edition adds even more: a SQL database server, the Internet Security and Acceleration (ISA) Server firewall and Web caching solution, and FrontPage 2003 for creating Web pages. The cost of the SBS software is much lower than if you bought all these server programs separately, and hardware cost is reduced because you can install it all on one machine as an integrated package.
Scaling up with server consolidation
But what happens when you outgrow SBS or you want a little more separation for your servers, for better security and easier management? The next logical step is to buy more server boxes and set up one to be a domain controller, one to be a mail server, one to be a Web services (HTTP, FTP) server, and so forth. The hardware vendors will love you for doing it that way, but it will get expensive, and if you're crunched for space, you might even find yourself needing to expand your office space requirements to accommodate all that new hardware.
There is a way to enjoy the security benefits of separate servers without as much added expense and the resultant space problems. Consider server consolidation: running multiple servers on a single, high powered machine.
Wait a minute! Isn't that exactly what you were doing with SBS? Well, sort of. The problem with SBS is that all the server services are running on the same installation of the operating system. That means you can't, for example, disable Web services on your file server to prevent hackers from exploiting IIS to get at the files stored there. You need IIS operational because your file server is also your Web server (and your everything-else server).
Consolidating servers with VM software
When you consolidate servers using virtual machine software packages such as those made by VMWare and Microsoft, you have multiple instances of the operating system (or even several different operating systems) running simultaneously on the same physical machine. Each virtual machine (logical computer) has its own IP address, computer name, OS configuration, applications, etc.
They can all communicate as separate entities with each other, or with other computers, on the network. Even though your Web server, your file server and your Exchange server are all running on the same piece of hardware, they appear to users on the network as different computers, and you manage them individually.
Now you can disable unneeded services on each of the servers. You don't have to deal with the security risks of having your firewall machine running productivity applications, or having your domain controller also serving as your FTP server.
Selecting the server consolidation software
You can consolidate servers using VMWare Workstation or Microsoft Virtual PC software. This is a less expensive solution and you may want to start out on your server consolidation adventure this way. However, both companies make more robust VM servers that can handle multiple productivity servers better.
VMWare's product is GSX Server and Microsoft's is Microsoft Virtual Server 2005. These both run on Windows (GSX can also run on top of Linux). VMWare also makes a dedicated virtual server operating system called ESX that is built on the Linux kernel and provides even higher performance.
As your business grows, you might want to upgrade to these higher performance (and higher cost) products. For example, GSX server supports 2 to 8 CPUs, typically handling 4 simultaneous virtual machines per CPU. ESX supports 2 to 16 CPUs and handles 8 VMs per CPU. Whereas GSX can scale up to the enterprise level, ESX provides a datacenter-class virtual infrastructure. GSX Server with an unlimited CPU license costs about $2,800; ESX Server costs considerably more (around $8,000, depending on the vendor).
Microsoft's Virtual Server is much less costly, at $499 for Standard Edition (up to 4 processors) and $999 for Enterprise Edition (up to 32 processors).
Selecting the server consolidation hardware
Because your single machine will be running multiple virtual systems, it's important that you run it on hardware that's capable of supporting all those VMs. Minimum processor speed (and number of processors) and RAM requirements depend on how many virtual machines you'll be running simultaneously.
Microsoft recommends a 1 GHz or faster processor for Virtual Server, and 256 MB RAM plus the amount of RAM you want to allocate to each virtual machine. We would recommend at least 512 MB of base RAM plus the VM allocation. Thus, if you want to run three virtual machines and allocate 256 MB of RAM to each, you would get good performance with between 1 and 2 GB of RAM. VMWare specifies a 733 MHz or faster Pentium-compatible processor and a minimum of 512 MB of memory for the host.
When it comes to hardware resources for a server consolidation machine, more is always better.
Debra Littlejohn Shinder, MCSE, MVP is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. Deb is a tech editor, developmental editor, and contributor to over 20 additional books on subjects such as the Windows 2000 and Windows 2003 MCSE exams, CompTIA Security+ exam, and TruSecure's ICSA certification.