How to Choose Server Memory

Feb 2022

By Simon Besteman

#KingstonCognate introduces Simon Besteman

Photo of Simon Besteman: an ISP, supplier, data center consultant

Simon Besteman is a French and Dutch national, and a veteran of the ICT and data center industry. He has over 20 years of experience working at ISPs, suppliers, and data centers and as a management consultant for a wide range of organizations. Simon has held various senior management positions in multinational companies in the areas of service, sales and marketing, operations management, and strategic development.

Currently, Simon is the Managing Director of the Dutch Cloud Community, the Dutch coalition of hosting providers. As a leading representative of the industry, he is a frequent blogger on industry and policy matters, a keynote speaker at congresses and conferences, and a participant at Dutch government round tables on matters relating to telecommunications, data centers, and internet regulation. He sits on the boards of various industry groups, with a focus on education, employment, and governance.

Memory is a critical component of any system and configuring it the wrong way can drastically impact the performance of your system and application.

Before deciding how to populate your server, which type of memory to use, and how much of each memory module to install, you need to understand the importance of the choices you make, or you may end up with disappointing performance, higher than expected power consumption, or even more serious issues, such as the system not powering up at all.

The Different Types of Memory Technologies

The first thing to think of is compatibility. Mixing memory modules from different brands in the same memory bank may result in compatibility issues. If the wrong memory is installed or memory technologies are mixed, the system might power on, but not boot to an operating system.

There are three main memory technologies available today: UDIMM (Unbuffered DIMM), RDIMM (Registered DIMM), and LRDIMM (Load Reduced DIMM). Even though these three memory technologies fit physically in the memory slot of your server, they CANNOT be mixed and doing so will lead to system boot failure.

How to Choose the Right Memory

A stack of memory modules fanned out on a dark background

UDIMM, RDIMM, and LRDIMM also come with different memory speeds. Servers today are compatible with DDR4 memory modules running at speeds up to 3200MT/s. However, this memory speed can vary and clock down depending both on the processor model used and the number of memory modules installed.

Think of it as a freeway. Traffic must slow down when there are a lot of cars driving on the freeway otherwise there will be a crash. It is the same principle with servers. When a lot of memory modules are installed, the system must slow down the memory frequency to be able to handle the higher amount of data traveling to and from the memory modules.

Another important check is whether you are compliant with the platform and manufacturer's memory installation guidelines. Today, there are multiple platforms with different memory channel configurations available. There are four, six, and eight memory channel motherboards available now and twelve memory channel motherboards coming later this year. Kingston Memory Search helps you choose a compatible part number and also provides you with information about your system.

What to Consider when Configuring Your Server

For best performance, it is important to install memory modules as per the platform architecture recommendation. This is what we call a balanced memory configuration. Not following the platform’s memory channel configuration guideline will result in loss in memory performance or an unbalanced memory configuration.

Many customers install low-capacity memory modules into their servers. There are a few challenges with this approach:

Scalability: If you fill up the server with low-capacity memory modules, you will not be able to add memory modules in the future. You will have to remove the existing memory modules and buy new ones to achieve maximum capacity.
Power consumption: Installing a greater number of memory modules will draw more power.
Performance: Remember the analogy about the freeway? Fully populating the server will most likely result in drop of memory speed.

Understanding the Application Is Key to Success

Purchasing the cheapest option available is often not the most cost-effective approach if you look at the total cost of ownership. Really take the time to research your platform specifications, your upgrade options, and what your application needs are.

If your application requires a high amount of memory capacity, you will need to look at RDIMM and LRDIMM memory technologies. If your application is memory-bandwidth sensitive, then you will need to look at the processor model installed and the number of memory channels featured on your platform. If it is an eight memory channel platform, it is best to install the memory modules in groups of eight per processor to get the best performance. Some platforms limit memory performance when modules are installed in the second bank, also referred to as 2DPC (2 DIMMs per Channel).

Finally, you will also want to consider installing dual-rank-based memory modules because they offer better memory performance over single-rank memory modules.

The Best Memory Partner for Your Solution

Kingston offers 3200MT/s server memory modules, which are the fastest DDR4 memory modules available before we move over to DDR5 server memory later this year.

As you can see, upgrading your system is not as straightforward as you may have thought. For this reason, Kingston provides customers with a FREE and tailored support service "Ask an Expert". Whether you need to install memory, an SSD (Solid State Drive), or any other products, Kingston will assist you and provide you with advice and the best solution for your business needs.

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