I came across these two items of non-integer rack unit height:
1. This rack mount kit which seems to be trying to make the best of the slightly-taller-than-1U form factor of the Cisco ASA5505.
2. This 1.5U Server Case that espouses the merits of a case height between 1RU and 2RU.

My questions are as follows:

A. (1) seems to protrude 1/8 RU above and below the rack unit it is bolted in. Is there any way to make use of the 7/8 RU remaining above and below? Or would using that bracket effectively consume 3 RU?

B. Are there any gotchas I should be aware of (like rack rail bolt patterns not working out, etc) when I consider one of these non-integer RU server cases like (2)?

  • +1. Some Ciscos 2970 and 3550 and 3750 are 1.5RU tall and that's not really convenient in most deployments.
    – petrus
    Nov 4, 2012 at 21:55
  • Odd. But I guess 2 x 1.5U = 3U?
    – hookenz
    Nov 4, 2012 at 22:44

1 Answer 1


You're supposed to use the 1.5 rack-unit equipment in pairs... But that's really a nonstandard setup.

For the Cisco ASA 5505, it's really a desktop/tabletop SOHO device. When I use them in data centers or rack setups, I usually place them on a shelf (which is usually a fraction of a rack-unit as well). Nobody uses a rackmount kit for that device... Well, maybe, but I have yet to see one in the field.

  • 1
    You just beat me to the same answer :-) Place on a shelf or combine with other non-standard stuff. (KVM's, networked USB hubs, modems, etc.) Don't be tempted to mount this stuff 1 hole lower or higher than an integral unit. Sooner or later things get ugly that way.
    – Tonny
    Nov 4, 2012 at 21:54

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