Difference Between 1u and 2u Rack Server

Nowadays, in the context of data centers and server rooms, space efficiency is a big challenge. Rack servers nowadays are an essential standard for organizing or maximizing available space. There are two most common configurations available: 1U and 2U rack servers. What is the difference between these two types, and which one should you choose for your needs?

This blog post will walk you through the differences between 1U and 2U rack servers and their respective advantages and help you understand what use cases best suit them.

Understanding Rack Units (U)

Before discussing 1U and 2U servers, let's understand "U." In rack server terminology, "U" stands for "rack unit" or "unit," referring to a standardized measurement of vertical space in a server rack. For instance, 1U equates to 1.75 inches or 44.45 mm in height. As much as standard sizes exist for server racks, the common sizes used are 42U.

This translates to about 6 feet in height, at 1.8 meters. In this regard, 1U Rack Servers: 

Space-saving and Efficient

1U rack servers, as the names themselves describe, occupy one unit of vertical space in a rack server. These servers are minimal in size and have maximum computing power. Here are some of the few salient features of 1U servers:

Size and Form Factor:

Height: 1.75 inches (44.45 mm)

Width: 19 inches (482.6 mm)-standard rack width

Depth: Varies, typically 20-40 inches (508-1016 mm)

Components and Expandability:

General support 2-4 hard drives or SSD

Few PCIe expansion slots usually in 1-2

Contain usually 1-2 CPUs

RAM capacity varies but is generally lower than 2U servers

Cooling:

To Use smaller, high-speed fans

Tend to run a bit hotter because of compact design

Power Efficiency:

Will tend to be more power-efficient because of less components

Use Cases

- Web servers

- File servers for small and medium business

- Lightweight database servers

- Edge computing applications

2U Rack Servers More Capacity and Expandability

2U Rack Servers

These servers occupy two rack units of vertical space. This gives them room for more components and more expandability. Below are the key characteristics of 2U servers.

Size and Form Factor:

- Height: 3.5 inches or 88.9 mm

- Width: 19 inches or 482.6 mm - the standard width of a rack

- Depth : depends, typically 20-40 inches or 508-1016 mm

Components and Expandability

- Accommodate more hard drives or SSDs: usually 8 to 24 in number

- PCIe expansion slots: usually 3 to 7

- Housing 2-4 CPUs

- More RAM capacity compared to that of 1U servers

Cooling:

- Bigger fans for improved cooling

- They tend to run cooler because of improved air circulation around them

- Power Consumption:

It will use more power because of the extra components

Use Cases:

- Database servers

- Virtualization hosts

- HPC

- Storage servers

- Application servers where the workloads are resource-intensive

Differences and Considerations

The choice between 1U and 2U rack servers should, therefore, consider the following differences: 

Density vs. Expandability:

1U servers can pack more servers in a rack, which is beneficial when a proper amount of space is scarce. 2U servers don't take up as much vertical room, but they do have better expansibility and are usually better when additional storage or computer power is needed.

Cooling and Noise:

1U servers run hotter and noisier due to their compact design and higher speed, as well as smaller fans. 2U servers are cooler and possibly quieter, therefore a better choice for noise-sensitive environments.

Performance and Scalability:

Even though both 1U and 2U servers can be very powerful, 2U servers usually leave room for added high-performance components and future upgrades, making them more suitable for applications that need scaling up.

Power Efficiency

1U servers tend to be more power-efficient per server, as they are generally smaller and carry fewer components. For applications requiring the highest level of performance, however, 2U servers offer better overall efficiency because they often can consolidate workloads that otherwise might be distributed across multiple 1U servers.

Cost

1U servers are less expensive upfront in part because they have a smaller footprint and lower parts count. However, 2U servers can pay for themselves in the long run when high performance or frequent upgrades are needed to keep applications alive.

Conclusion

This is mainly a question of your specific needs and limitations. 1U servers excel in dense environments where space is limited, such as web hosting or edge computing applications, while 2U servers represent the best choice in applications that can consume more power, storage, or just more expansive needs in general, such as database servers or hosts of virtualization.

The factors involved in this decision would be a consideration of present and future requirements for performance, the use of available rack space up to a high degree, power and cooling capacities, as well as budget constraints. This will help you conveniently opt for the right rack server configuration that best addresses the needs of the organization and helps prepare for long-term success.