Be aware all racks do not come the same. The overall framework will fit the standard but the gremlin is in the details with the 2 post server rack. Having one hundred bright shiny new servers ready for installation in a day goes easier if a person knows the standard and the hazards of such an enterprise.The standard comes from the Electronic Industries Association and has been labeled EIA-310_A.
It defines the standard rack which in this case features 19 inch racks, vertical and horizontal hole spacing, a front panel width and the rack opening itself. Why doesn’t’ your gorgeous new piece of computer equipment fit in the hole?
The standard defines a few key features and has for over 50 years. It has developed over time with added choices because different servers appeared. When searching for a server hole shape, and the depth of the rack mounting; how the rear and front space shapes up, needs consideration. Each manufacturer does it differently. So a set of servers may fit well in one rack but not all servers.
Measurement and placement come as the two aspects that must have alignment for equipment to fit. So what are the numbers and where is the placement?
Vertical Hole Spacing
- Repeating holes patterned within 1.75 inches
- Alternates ½ inches, 5/8 inches, 5/8 inches and repeats
Horizontal Hole Spacing
- Center to center hole dimension comes at 18.312 inches most of the time
- Have evolved to slots to allow variation in equipment now
- 17.72 inches
- 2 post racks trend has been to be a bit larger than that
Where does the 19 inches come from? It comes from the front panel which does measure that.
2U 2-Post Conversion Kit
Do not panic if the fit does not come perfect. Engineering means dealing with ranges and tolerances by having solutions or modifications. Because of the inconsistencies within the standard and the fact technology evolves, manufacturers developed kits to bridge or modify the features. A metal flange in the shape of a long U solves the problem and often converts the rack to the needed dimensions easily.