Rack Mount Enclosures and Server Racks
By Mark Boehm
Rack mount enclosures, rack mount cabinets, server racks, what does all this
mean? In most cases these terms refer to a convenient way to organize and store
multiple computers (servers) or other types of computer equipment. These rack
mount enclosures offer an effective way to store a large volume of computers in
areas that offer limited space.
With all of these server cabinets being available in so many sizes and all those
options that are available to the end user, there’s no wonder why there isn't
more confusion then there already is on which rack mount cabinet to choose from,
so let's start with some basics.
The most common type of rack mount cabinet is known as the "EIA standard" or 19-
inch rack mount cabinet". Most rack mount computer equipment is what we call a
"standardized” 19 inch width. The internal width of these rack mount enclosures
is the "EIA standard" of 19 inches, so when you are trying to determine how many
servers and shelves you want your server rack to contain, they will all be in
this standardized 19 inch format.
All computer heights are measured in units called "U's". Now don't feel bad,
this took me a bit to catch on to this concept too. When I went to school
everything was either measured in inches or centimeters, but when working with
rack mount enclosures things are done just a little differently. In the world of
computers, when referring to the height of a computer, 1 "U" equals 1.75 inches.
So when shopping for rack mount cabinets you will see references to cabinets
like 10u, 12u, 25u and so on. So what does all of this mean to you? There are
obviously hundreds of different sizes of server racks and multiple choices of
shelving systems that can be put in to these rack mount enclosures. So in order
to determine how much space is available for equipment and shelving options, the
cabinets are rated in U's.
For example: If I am looking at a rack mount cabinet that has a rating of say
25u. I of course need to choose some shelving that will fit into this cabinet
for my specific application. So how do I know how many shelves I can fit in to
my new rack mount cabinet? Well you will also find that the shelves for these
cabinets are also rated in U's.
If I choose shelving that has a rating of 5 U's, then this particular server
rack that is rated at 25 U's will accommodate 5 shelves. Because each shelf
takes up the space of 5 U's inside the rack mount enclosure. If I choose shelves
that have a rating of 12 U's each, then this rack mount enclosure will only
accommodate 2 of these shelves. Once you catch on to this new concept of
measurement it really does become quite easy to use and understand.
Airflow is always an issue when it comes to rack mount cabinets. Computers
produce a lot of heat when operating, so dissipating this heat becomes critical
when storing multiples of these devices inside of a single cabinet. This is
certainly something you will need to take in to consideration when purchasing
your server rack cabinet. You will also want to consider noise and cable
management as well when making your purchase. All of these issues and more will
be covered in future articles.
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