The complete guide to buying a server rack

 

There are many variables to be aware of when setting up IT equipment in a server rack. Because of this, pairing mounting equipment with IT equipment can be complex. In order to make effective use of your time and money, it’s important to be prepared before purchasing and building. 

That’s why we’ve made this guide. It’s designed to cover everything you might need to know before purchasing a server rack and the mounting equipment to go along with it.

What equipment are you mounting?

Before you start looking around, you will need to know the dimensions of your servers and other IT equipment. Ideally, you will be familiar with both the dimensions and model of your IT equipment before purchasing a rack or mounting rails.

Equipment Dimensions 

The dimensions of your server need to satisfy the internal limits of your rack. Be sure not to confuse the mountable (internal) dimensions with the rack (external) dimensions of servers that you are looking for. 

Equipment Height

Rack U Spacing
Illustration of rack unit spacing

Rack-able equipment height is always described in terms of rack units. Otherwise known as “U’s”, rack units take up three holes on a rack for a total of 1.75 inches. 

Servers manufacturers tend to list a model’s U height right next to its name. It should be very easy to look up your model and find out its height. 

Equipment Width

Rack EIA-310 width standard
Width measured by EIA-310 standard

When it comes to the width of the equipment that the rack will support, it is measured in EIA-310 standards of 19, 23 or 24 inches. Even if you’ve just begun researching server racks, you might have stumbled upon the phrase “19-inch rack.” This is because 19-inch servers are very common in comparison to 23 or 24 inch counterparts. 

Equipment Depth

Rack Depth
Illustration of rack depth (perspective from the side of a rack)

Equipment depth must fit within a rack’s internal depth. The average rack depth falls 36-42 inches but it can vary greatly between different types of racks. Rack depth generally exists in a 0-50 inch range. 

Types of server racks and how they fit your needs

Once you’re familiar with the dimensions of your equipment, it’s time to start learning about different types of racks. Server rack variants exist to satisfy different security and space needs.

There’s no step by step process in choosing racks due to the wide variety of options, but there are a few overarching categories. Your rack will either be open framed or enclosed with either 2 or 4 posts.

Open-frame rack vs. enclosed cabinet rack

4-Post Rack
4-Post, Open Frame Rack

Open-frame racks are server racks with an entirely open design. This gives you complete, convenient access to make adjustments to your equipment. Because there is less metal, open frame racks typically cost less than similarly sized enclosed racks.

Airflow cannot be controlled with an open frame rack as easily as in an enclosed frame. Still depending on the environment of the room, open frame racks can benefit from free flowing air.

Physical security is also harder to come by in an open frame rack. There are products that can lock individual equipment mounted on an open frame rack, but purchasing those for every server can become expensive. If you are looking for a more affordable option, an open-frame rack might be the way to go.

Enclosed Rack
Enclosed Rack

Enclosed racks have physical walls around the rack that keep equipment in a closed area. If physical security is a priority, an enclosed rack is the way to go. Many of these racks are lockable and thus, you can limit who has access to server equipment. 

Because enclosed racks aren’t accessible from the sides and have doors, they make equipment less accessible and maintenance more difficult in certain spaces. In order to route cables with an enclosed rack, customers might need to utilize overhead trays or space underneath a raised floor.

2-post rack vs. 4-post rack

2-Post Rack
2-Post Racks

2-post racks are equipment racks that have two vertical upright support beams. These can handle less load than a 4-post rack so most people use 2-post racks to mount lighter equipment such as patch panels, switches, AV equipment, or network equipment. 

Many businesses use a 2-post rack specifically as a networking rack, housing modems, switches, routers, and patch panels. 2-post racks have several benefits, including complete access to airflow for easier cooling, a convenient size, and a more affordable price than 4-post racks. 

Considering these factors, 2-post racks are best in a small server room or IT closet that needs less equipment mounted. However it is possible to increase the load capacity of a 2-post rack for use with heavy equipment by bolting it to the floor or using a 2 post converter.

4-post racks have four vertical support beams. The additional beams provide more support, which allows you to rack mount more heavy duty equipment. 

With their additional support and greater depth, 4-post racks can mount just about any IT equipment, but are often used for servers. This makes 4-post racks extremely versatile and more sturdy. Thus, while they are essential in a larger IT facility, such as a data center, they can be employed in a small server room as well.

Server rack construction

There are a range of materials that are used to make server racks and mounting equipment. RackSolutions prides itself in building some of the highest quality racks in the industry, made completely out of steel in the United States. Construction can change the strength, build and cost of your server rack. 

Open Frame Rack
Open Frame Rack

Bolted vs Welded racks

Bolted racks are made by securing all the different parts of the rack (posts, walls, door, etc.) together with bolts and screws. The benefit here is that they are able to ship disassembled, saving on transportation costs. Unfortunately, you don’t have this same opportunity with a welded rack, as the assembly is permanent.

Welded racks consist of framing partially or fully welded together. While it might seem like a welded rack would be stronger and with a more reinforced structure, other construction methods can provide equal strength while providing additional versatility. Since welded racks are delivered fully assembled, it saves customers time and risk of putting the rack together incorrectly. 

Server rack load capacity

Load capacity can be thought about using one of two ratings: static load capacity or dynamic load capacity. 

Static load capacity is the amount of weight a rack can hold when it is stagnant and installed. This typically means the rack is bolted down, or sitting on leveling foot pads, not rolling casters. 

Dynamic load capacity is the amount of weight a rack can withstand while rolling on it’s casters.

The static load capacity will always be greater than the dynamic load capacity. Dynamic load is worth considering if you are going to be moving the rack with equipment. You always want to get a rack with a higher load capacity than needed to be on the safe side. Single racks can have a static capacity of up to 4000 lbs

How would you like to mount your equipment?

The last essential step in mounting your equipment is to find some racks or shelves to install. Generally, rails are used for equipment that was built with the intention of mounting whereas shelves can be used for anything that fits on them. 

OEM vs Server Specific vs Universal rails

OEM rails
Server Specific Rails

OEM rails are typically only available at the time of purchase or from a reseller. They are created by the brand who is selling the server. The main appeal to these is that they can be shipped with servers you are buying.

universal rails r710
Universal Rails

 

Server Specific rails are designed to fit similarly to OEM rails, but are made by a third party. These are available to purchase first hand at any point in time. 

Universal rails are essentially shelves that only hold equipment on the edges. They will fit any server because their depth and width is customizable. 

These rails don’t have features to lock equipment in place like OEM rails which means they can slide out easily for maintenance. If your server supports thumb screws, you will be able to lock the server into place using the middle holes of a given U space.

 

Slide vs fixed

Slide rails are useful for maintenance and removal of servers. The more servers a company has, the more likely they are to need frequent maintenance. Having as many slide rails as possible in a server room can have compounding advantages in efficiency. 

 

r710 slide rails
Slide Rails

Fixed rails are stagnant and typically more affordable than slide rails. These are perfectly adequate for small server rooms that don’t have to worry about constant maintenance. 

 

fixed server rail
Fixed Rails

 

Server rack shelves

Shelves are best suited for IT equipment that doesn’t have the capability of being mounted on rails. This includes switches, routers, AV equipment and any other IT equipment that has less than a 19 inch width. 

 

Server rack shelf
Server Rack Shelf

Shelves are particularly useful when you need to store equipment that wasn’t designed to be mounted inside of a rack. For instance, heavy-duty shelves are the ideal way to mount a UPS or tower computer in your rack. 

 

Mac Mini Shelf
Server Rack Shelf for Mac Minis

For smaller equipment, there is a large variety of shelf options. For example, switches can be mounted in an adjustable switch shelf, mac minis can be mounted in shelves specially designed for mac minis, and AV equipment can be mounted in a 2 post rack sliding half shelf or similar alternatives. 

These are just a few of the niche, tailored products that help you find the right solution for any equipment. 

Accessories for your server rack

Even with a few pieces of mounted equipment, there starts to be a need for additional products to help manage your system. Accessories can make such a dramatic improvement to your rack that they are almost necessary in certain situations. 

Cable management

 

Offset Cable Tie Bar

Cables can get out of hand fast when all of your equipment is interconnected. Whether you’ve filled a 40U or 16U rack, cable management techniques remain consistent and can be easily solved with a few products. 

The general idea is to aggregate cables traveling anywhere other than in an input to the vertical cable management bars running up and down the rack. When they are entering or exiting an input, they run through horizontal cable management bars

They can further be organized and kept track of by using different colors for different cables, labeling them and using zip ties or straps.

Kvm mount

 

KVM rack mount
1U KVM 1 Port Console

The “KVM” in KVM mount stands for Keyboard, Video and Mouse. Basically, these allow you to store a keyboard, monitor and mouse inside of as little as 1 unit of rack space. 

More advanced KVM units are also able to switch through inputs. This means that with a flick of a button you would be able change the server that is displaying and control it. 

The mount by itself is useful for anyone that has a server rack because it slides out and back into place, taking up barely any room. You can also purchase a KVM switch later on that gives you more advanced functionality. 

Fans 

 

horizontal rackmount fan
3U Horizontal 19″ Rack Fan

The primary use case for fans in a server rack is to break up hot spots. These occur in areas where there is slow ventilation. For instance, if a part of your server rack is empty and heat is rising from equipment beneath it, it might stay at a higher temperature than anywhere else in the rack. It’s a vicious cycle that results in higher running temperatures on servers than needed. 

There are plenty of products available to fix any hot spot. Some servers have room for fans at the top, a common area for hot spots to develop. If yours doesn’t have space, you can get a vertical fan that takes up 1U of rack space or a horizontal fan that takes up 3U of space. 

Rack mountable power supply

 

rackmount pdu
20A Horizontal Rackmount Power Strip

Having a PSU close by can be very convenient. RackSolutions sells rack mountable PSUs that can attach to your server just like a server rack does.

If you don’t have U space to mount these in, then you can also hang them from a vertical cable management bar. 

Converters and adapters – if things don’t fit perfectly

There are tons of incompatible items when it comes to racking equipment and accessories. Thankfully, adapters exist for most of the issues. 

2 post conversion bracket

conversion bracket
2 Post conversion kits allow 4 post equipment to be mounted in 2 post racks. You can do this with flush mount brackets or center mounted brackets.

Width adapter kits

server rack width adapter
Reducer brackets are the only adapters that adjust width. They are designed to let users mount 19 inch equipment in 23 or 24 inch racks.

Depth adapter kits

serve rack depth adapter
You can both expand and decrease the mountable depth of your rack using Adapter Brackets. Install them outside of the rack and they expand depth, install them facing inside and they decrease it. 

RackSolutions can help you figure things out

If any of this left you with more questions, or if we didn’t dig deep enough into a topic, feel free to contact us with any questions. If you want to skip the call, our other blog posts might address topics more thoroughly: 

 

Guide How to Buy a Server Rack