Standard DC rack rail distance, front to back question

Thu Apr 27 21:05:58 UTC 2023

On Thu, Apr 27, 2023 at 09:51:36AM -0400, Chuck Church wrote:
> Hey all.  Question about standard 4 post racks.  We bought some that are
> adjustable.  Unfortunately, the posts are very flimsy, as these are some
> fancy cabinets with spacing on the sides for vertical patch panels, etc.  We
> found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU
> switches) are sagging quite bad.

A perpetual problem with Cisco all the way back to their 2501 routers.
Sometimes they seem to come out with a better design, only to
revert back to the worst design the next generation of gear.

> Is there a 'standard' distance between front and back rails
> that devices usually adhere to?

I've got about 5 different "standard" depths in my datacenter. The
most common I have is 29.5" because that is the depth of a whole bunch of
fixed (ie. not adjustable) shelves I have are.

I've seen 32" and 36" in use for newer setups, as the eqiupment keeps getting deeper,
and deeper. Most equipment today will adjust for different depths quite
readily, and stick out past the back rails (so those 1050mm or 1200mm deep cabinets really
don't give you lots of empty space when the gear inside requires all that depth, then
power cables take up the rest).

So, ultimately the depth doesn't matter much as the rails will adjust to what you have
within reason now-a-days.

Gone are the days where equipment (ie. Sun, DEC) only fit in that one
rack that Sun paired with that specific Sun line. And when you bought different
Sun gear, you needed to buy a different rack to hold that.