Servers for Virtualisation: VMware & Hyper-V Guide

Virtualisation is one of the most common reasons businesses invest in dedicated server hardware. Whether you are running VMware vSphere or Microsoft Hyper-V, the physical server underneath your virtual machines does a lot of heavy lifting. Get the spec wrong and you will feel it sluggish. VMs, bottlenecked storage, and hosts that run out of headroom faster than expected. The good news is that you do not need to spend a fortune to build a solid virtualisation host. Refurbished enterprise servers from brands like Dell, HPE, and Lenovo are built for exactly this kind of workload, and they are available at a fraction of the cost of new hardware. This guide will help you understand what to look for, what to avoid, and how to match a server to your actual needs. We have also linked to some of our preconfigured server options throughout, so you can see real examples of hardware that suits virtualisation workloads right out of the box.

Key Considerations

CPU cores matter most: More physical cores means more virtual machines running comfortably. Look for dual-socket servers with high core-count processors.
RAM is your biggest constraint: Each VM needs its own memory allocation. Start with at least 128 GB and plan for more if you are running a busy environment.
Storage speed affects everything: Slow disks hurt VM performance badly. NVMe or SAS SSD storage is worth the investment for your primary datastore.
Check processor compatibility: VMware in particular has strict hardware compatibility requirements. Stick to processors on the HCL (Hardware Compatibility List).
Network throughput is often overlooked: VMs share network interfaces. At minimum, look for dual 10GbE NICs or a server that supports them.
Plan for expansion: Buy a server with spare RAM slots and drive bays so you can scale without replacing the whole host.
Consider redundancy: Dual power supplies and hot-swap drives are standard on enterprise servers and important for uptime in a virtualised environment.

Choosing the Right CPU for Your Virtualisation Host

The processor is the foundation of any virtualisation server. Both VMware and Hyper-V schedule workloads across physical CPU cores, so the more cores you have available, the more virtual machines you can run without them competing for resources.

For most small to mid-size environments, a dual-socket server running Intel Xeon E5 or E7 series processors (or their newer equivalents) is a practical starting point. A dual-socket server with two 10-core processors gives you 20 physical cores, which typically translates to 40 logical cores with Hyper-Threading enabled. That is a solid foundation for running 20 to 40 small to medium VMs depending on their workload.

If you are running VMware specifically, check the VMware Compatibility Guide before you buy. Older generation processors are generally fine for vSphere 6.x and 7.x, but newer versions of ESXi are starting to drop support for very old CPU families. It is worth confirming your chosen processor is supported before committing.

How Much RAM Do You Actually Need?

Memory is almost always the first thing that runs out on a virtualisation host. Each VM is assigned a block of RAM, and unlike CPU, memory is not easily overcommitted without performance consequences. VMware does support memory ballooning and transparent page sharing, but these are safety nets not a strategy.

A sensible rule of thumb is to add up the RAM you plan to allocate to all your VMs, then add 20% headroom for the hypervisor itself and future growth. For a small environment with 10 to 15 VMs, 128 GB is a reasonable starting point. Larger environments or those running memory-hungry workloads like SQL Server or SAP should look at 256 GB or more.

Enterprise servers like the Dell PowerEdge R730 and HPE ProLiant DL380 Gen9 support up to 1.5 TB and 3 TB of RAM respectively in their maximum configurations, which makes them popular choices for growing virtualisation environments. Many of our refurbished listings include these servers with RAM already configured so you can find options that match your needs without building from scratch.

Storage: Where Most People Get It Wrong

Disk performance has a direct impact on how snappy your virtual machines feel. If you put 20 VMs on a single traditional hard drive array, they will all be competing for read and write operations at the same time, and users will notice.

For your primary VM datastore, SSD storage is strongly recommended either NVMe drives for the best performance, or SAS SSDs as a cost-effective middle ground. Spinning hard drives (HDDS) are still useful for secondary storage, backups, or archiving, but they should not be your main datastore if you care about performance.

Also think about your storage controller. Enterprise servers come with hardware RAID controllers that offer caching and better write performance. Make sure your chosen server has a controller that supports RAID 10 or RAID 5 across your drives, and that the cache battery or flash-backed unit is present and working especially on refurbished hardware.

Networking and Other Practical Considerations

In a virtualised environment, all your VMs share the host's physical network interfaces. If you only have a 1GbE connection, every VM on that host is sharing one gigabit of bandwidth. That is fine for light workloads, but anything involving file transfers, backups, or database traffic will feel the squeeze quickly.

Dual 10GbE network ports are a sensible minimum for a production virtualisation host. Many enterprise servers support 10GbE via add-in cards or onboard ports, and some support 25GbE or higher if you are building for the future. Separating management traffic, VM traffic, and storage traffic onto different VLANs or physical interfaces is also good practice and worth planning for at the hardware stage.

Finally, do not underestimate the value of a proper out-of-band management interface. Dell's iDRAC and HPE's iLO both give you remote access to a server even when the OS is down. For virtualisation hosts sitting in a rack somewhere, being able to restart a hung ESXi host or check hardware health without physically touching the server is genuinely useful.

Quick Summary

Choose a dual-socket server with a high core count processor - more cores means more VMs running comfortably.
Start with at least 128 GB of RAM and build in headroom; memory is the most common bottleneck in virtualised environments.
Use SSD or NVMe storage for your primary datastore - spinning disks will hurt VM performance under load.
Make sure your hardware is on the VMware or Hyper-V compatibility list before you buy, especially for newer hypervisor versions.
Plan for dual 10GbE networking, redundant power supplies, and hot-swap drives these are standard on enterprise hardware and make a real difference to uptime.

Looking for refurbished IT equipment?

Browse our range of tested and graded servers, workstations, storage, and networking hardware.

Shop Now