In a previous blog post, “Spending Money To Make Money: An IT Strategy That Really Works?” I compared the cost of running 6-core, 8-core, and 12-core CPUs across the x86 enterprise, comparing costs among the versions. My point back then was that more expensive servers could actually save you money when looking at the TCO. Now that Intel is producing 14, 16, and 18-core CPUs, I wanted to go back and see where these machines fit in terms of price and performance.
An Updated CPU Cost Comparison
While these 18-core CPUs are hot-rods featuring 5.69 billion transistors, 45MB of L3 cache, DDR4 RAM support and 9.6GB/sec of QPI, they are very expensive.
Who would argue that buying the most expensive servers is a smart business choice? Actually, I will, with some caveats.
While these CPUs make the top 5 list for VMmark’s performance specs, they actually hit #1 when we factor in power costs and cooling efficiency. So let’s do a high-level ROI when factoring in hypervisor and OS costs. One caveat up front: When I say “most expensive server,” I’m actually talking about a specific CPU line. I like the most expensive Intel E5 CPUs, which are more affordable than the top E7 CPUs. The E7 is the true top-of-the-line CPU and may only be necessary for the absolute most demanding workloads. That said, the E5 tends to follow the consumer market, which arguably moves faster than true enterprise. So the E5 benefits from having newer technology faster, which is a benefit as well.
Let’s take a look at a VDI requirement that is based on 400 concurrent users of Citrix. If the requirement is 72 physical cores and 1.5TB of RAM, there are a few different ways to satisfy the requirements with differences of cost and number of servers (using hp.com “customize and buy” as of November 11th 2014 for pricing estimates, 32GB DIMMs, 2.3Ghz CPUs with redundant power, fans, rail kit, and no hard disks).
CPU Cost Comparison Analysis
While the 6-server option is still the cheapest, if we factor in the space in the chassis, power, cooling, not to mention management overhead, it probably makes sense to purchase and install the larger servers.
The biggest benefit is longevity and density. A larger server can be repurposed later on, can scale for a different purpose such as a database server, a test/dev environment, software defined storage, whatever. These new servers will generally last longer than a 6-core server. You might even get 4-5 years out of these 18-core CPUs, but it’s unlikely that it will make sense to run 6-core CPUs.
The Bottom Line
When choosing a server, consider that spending more money on the fastest severs that are available today, should have many benefits: Reduced management overhead, reduced software costs (per-core database software aside), reduced power and cooling costs, and a smaller footprint if you are paying for rack space. And you’ll likely get more longevity out of them as well.