As for server hardware, we highly recommend rack-based units, even if you do not store them in a typical rack enclosure. The rack form-factor appears to be the de facto standard once you get to a certain level of power and redundancy, and is therefore usually offers better features and more value than the typical “tower” server.
You can save thousands of dollars by procuring a pre-owned Rack server. We typically aim for approximately 3 year-old units that were close to top-of-the-line at that time. Such a unit usually delivers more than enough power to host many virtual servers and meet the demands of most small businesses. Avoid getting a unit too much older than that, though, as it could lack important features that we take for granted now (such as CPU features that help enable speedy virtualization). When it comes to CPU and memory, bigger is better because it decreases likelihood of “bumping into the ceiling” of the server’s capabilities. On a bran-new server, adding high-performance CPU can easily cost thousands of dollars more than an average CPU. When you are buying a used server, the differential between a 3 year-old high-performance CPU and a 3 year-old average CPU is typically only a few hundred dollars.
We also recommend maximizing redundant features on servers. Dual power-supplies are a must, and are usually “hot-swappable” on rack servers. Redundant CPUs not only increase computing power, but in the unlikely event that one fails, your server should continue functioning. Hard drive redundancy is exceptionally important. With the proper RAID controller and properly-configured array, a server can withstand failure of one (sometimes more) hard drive without data loss or downtime. Hardware redundancy pays for itself the first time it prevents an outage of mission-critical applications or data. Redundancy is an absolute MUST, particularly if your server is host to multiple virtual servers.
Finally, business-grade server should feature remote hardware monitoring and management features. We recommend exploring these options and having a plan in mind that helps to ensure your hardware alerts you to any issues before they result in a system failure.
in short, we prefer a top-of-the-line 3-year old rack server rater than a bran-new modestly-priced unit. If you don’t have a server rack enclosure, simply place the unit on a shelf where proper ventilation is maintained.