For those who are in a dilemma of replacing all the servers in your enterprise environment or thinking to stagger the hardware refresh, here’s an article which will help you in widening your thoughts. Basically, all you need are three key elements in selecting a server for virtualization and those are CPU, Memory and Network I/O capacity and it is these three key components which help in balancing the workloads for consolidation.
Going through these key components on an individual note- CPU issues include clock speed and the number of cores. Please do not go for the fastest CPU available in the market. Instead opt for a CPU which will be more cost effective and which has modest CPU clock speeds. Go for a CPU with a larger number of cores instead and stick to two 2.4 GHz 10 core CPUs than a two 4 core CPUs operating at 3+ GHZ. When workload performance is really challenging, then you can invest on a faster CPU. If one really wants peak performance in a server virtualization environment, invest in a CPU with large internal caches.
Now, going through the second key component, it is a known fact that virtual machines reside in memory of a machine, so more memory will support additional consolidation. Therefore, ensure that there is always enough DDR3 memory to support the number of workloads you expect to run a system. For instance, let us suppose that a two 10 core CPU with 40 threads each is taken for potential workloads. If each workload uses an average of 2GB, then the server will require a minimum of 80GB memory. But in most cases, organizations go for the next closest binary amount of 96GB or even 128GB. So, here memory simply gets wasted. And if in case, we go for less memory, it will surely affect the consolidation status or performance. Thus, by choosing to go for memory resilience features such as a memory sparing or memory mirroring, more additional memory modules can be obtained and which will not add to the available memory pool. You can save these features for servers running mission critical workloads.
The third key component is Network interface where every network needs network access and so be sure that there is adequate bandwidth available on any server for virtualization. Nowadays, a 10 GbE NIC is being offered by default by vendors offering servers for virtualization. So, look for this feature in your server components and go for a vendor which offers such specifications.
Going with other hardware considerations, adding a graphics processor unit may demand at least one PCIe x8 slot. An expansion NIC adapter will need a slot while a storage network interface, such as a FC host bust adapter will also require a PCle slot. Be sure that the server can handle all of the upgrades that you intend to add.
If you are operating a data center and the requirement of server count is high, then go for server evaluation at first and bring in a server which can be tested for performance at full consolidation. If it meets all your demands, then go for the purchase or else go for another company which suits and offers systems as per your need. Thus, by doing so, you can identify possible oversights in system requirements and refine your specifications before making an actual purchase.
When it comes to timing your purchase, the choice lies wholly on the business objective, rather than the technicalities. Always the biggest purchase and upgrade will often net volume discounts. But this happens only when the company chooses to upgrade the entire fleet of servers at the same time.
Nowadays, most organizations opt to stagger server purchase across the system lifecycle. This results in less costly and less disruptive routine purchases. In addition to it, buyers can leverage the continuing evolution of server hardware. For example, high end CPUs that may be too expensive today might be affordable in a year or so. So, by opting for a high end sever in future, you can cut down your current investments to a certain extent. But if in case, you need a server with utmost performance and availability, then going with the current trend and obtaining a high end server makes complete sense.