A 2-post rack has two mounting rails, and a 4-post rack has four mounting rails. There are pros and cons to either option. It is important to understand the differences between a 2-post and 4-post rack to ensure your choice meets your current and future requirements.

Server Rack Rails

4-post racks are ideal for professional solutions such as housing servers like the Dell PowerEdge series. Most of these rack servers will be mounted on server rack rails in either a static or sliding rail setup. These server rack rails require a 4-post fixture to handle the relatively slim and long housing designs.

NavePoint’s Adjustable Rack Mount Server Shelf Rails are a value-oriented alternative to brands such as the Dell server rack rails.

Occasionally, a rack shelf can be used in place of rack rails on 2-post fixtures, but depending on the width of the rack server, the equipment may not fit inside the shelf.

Load Capacity

A 4-post rack has a higher weight capacity than a 2-post rack when comparing floor standing models. For example, NavePoint’s 45U 2-Post rack is rated for 881 lbs. of weight capacity, which is sufficient for most applications, but NavePoint’s 45U 4-Post rack is rated for 1322 lbs., which is 441 lbs. or 50% more.

However, the weight capacity difference on a similarly designed 2 and a 4-post wall-mount rack is often smaller.

Mounting Depths

Most 4-post server equipment comes with features that accommodate varying depths mounted in a fixed depth cabinet or rack. When choosing a 4-post rack or cabinet, it is important to make sure the enclosure meets your equipment requirements in terms of maximum and minimum mounting depths, and the mounting depth increments.

If you have a variety of mounting depths, a solution to accommodate is NavePoint’s Server Rack Rail Depth Adapter. These rack rail adapters can increase or decrease your mounting depth (within the maximum allowed by the cabinet) by 4” or 6”.

In a 2-post fixture, all you need to be concerned about is whether the rack’s maximum mounting depth is deep enough to accommodate the equipment. At NavePoint, we are seeing a trend of consumers mounting deep rack servers on vertical wall mount cabinets due to the rack’s ability to handle deep equipment in tight spaces. A vertical wall mount cabinet is a type of 2-post cabinet that mounts the equipment vertically, which eliminates the cantilever effect on deeper equipment and reduces the amount of protrusion from the wall. We will discuss the pros and cons of a vertical wall mount rack in future blog posts.

Check out NavePoint’s 5U Vertical Wall Mount Rack Enclosure - 36 Inch Server Depth for any edge computing, security server, or similar needs.

Rack Density

Although vertical wall mount enclosures have gained popularity, a 4-post enclosure is superior in terms of rack density. An enterprise data center can fit many more server units in a 1200mmm deep 42U server rack cabinet than any other types of enclosures with comparable floor space. Higher rack density not only contributes to lower real estate cost, but also a higher precision in thermal control due to less empty space.

Wrapping Up

A 4-post fixture design is more popular than a 2-post design in data server setups both large and small due to its higher capacity in both weight and rack density. However, with the advancement in edge computing, decentralized digital media production, and desktop processors, more people are taking advantage of the flexibility from a 2-post enclosure to build their edge nodes, personal smart home, NAS, or PLEX servers.

Feel free to contact NavePoint’s sales team to address any questions, sales@NavePoint.com

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