Just bought a couple 42U 19" rack/cabinets... they're "AI Optimized", which I think means marketing has optimized the brochure for the AI grift.

@mWare I see how this works. Geek chooses the 19" rack, and if the brochure has the buzzword-du-jour on it, it is easier to convince the accountant to approve the purchase/issue the PO. So the AI thing isn't to help you choose it, it is to help you convince the accounting department approve your choice.

@jfmezei that's the point of every brochure.

@mWare Out of cursiosity, do 19" racks come with "built in" elecrical plugs and a big cable with L5-30 or greater plug? are those options from 19" rack manufacturer or do you buy those separately and just fit inside 1U or 2U space at bottom ?

@jfmezei usually empty but a few include very basic power bars.

This setup we're doing a pair of 30A UPSes, so 4x 0U (aka vertical) PDUs - A/B for each rack.

@mWare Pardon my ignorance here, but is there some sort of place where the vertical PDUs connect to each other and to a big cable that goes down to plug under floor or on ceiling? The racks I have are ex Digital and had a simple power control at bottom Us with some condensers, breakers, switches (and remote control capability) and that unit then has plugs to power the disk drives or computers ( back then a single ~450 megabyte disk drive drew 15 amps of power).

@jfmezei our notion of standard 19" rack computer equipment really only emerges in the late 1990s. I think the only modern exception to the bare rack might be @oxidecomputer.

https://www.vertiv.com/en-ca/products-catalog/facilities-enclosures-and-racks/racks-and-containment/vr3150/

This is my go-to rack, where most people get 24" cabinets, barely wider than the 19" mounts, I get these 'monster' 31" cabinets so the cable management is pretty.

In the attached photo, I used the Ubiquiti 2U PDUs, but they're only suitable for 12A, and I really don't like switching PDUs since they dramatically increase the points of failure. I also, ironically, didn't need the width for any cable runs... but I never regret having it.

@mWare none of the screw holes will line up, there will be several random screw holes along one side, and none on the other and the top will have an inexplicable twist in it.

@ottaross and the cable managers have the wrong number of fingers, several of which will (inexplicably) be teeth, and sometimes a a can of WD40.

@mWare 19" racks existed well before the PC folks moved from placing desktop PC on wire rack shelves to using rack mountable PCs. I think all of Digital's non desktop computers were 19" rackmountable, and the fancy "plastic cabinets" for standalone units were 19" inside. The difference is in depth of cabinet and not allowing for equipment to "invade" past the 19".

Photo: I had to saw parts of the Apple rackmount kit for Xserve because it uses space outside the alloted 19", not expecting any rack structure till full depth of rack. (having rack that is less deep means that it encounterd such structure).

@mWare @oxidecomputer What I find ineresting is the move from coax Ethernet to twisted pair and ensuing switches resulted in switches having their cabling in the front (and fans in back). Before that, there was no cabling on front of racks except when you plugged in for diagnostics etc. Introduction of switches has led to much more sophisticated cable management than before.

Though at the National bank I had seen really neat clean cabling betwene their terminal serves and the DEC ones with RS232 ribbon cables neatly folded at 90° angles so cables left the server ports horizontal, and upon reaching edge of rack, folded and then down to my DECservers and then folded and horizontal again to reach my ports. (and this was an IBM shop that had no concept of RS232).

And also back then, data centres were on raised floors so all cabling went down from rack, whereas now, it all goes up to ceiling. DO raised floors still exist?

@jfmezei Of course the racks existed; when did standard computers in a 19" chassis become popular/common? I contend around Y2K when the internet boomed. For example, when I was at Nortel in 1997-2000 we were struggling to get rackmount PCs at all.

Gobs of lab equipment and some switching/patching was 19", I know in A/V 19" rack gear was common too. But 23" or proprietary cabs still ruled telecom, which is what Internet came from.

re: dimensions - I have modern HP Proliant servers that don't fit in my datacentre rack in Montreal with the rails. about 3mm too wide. Can't even bend the margins to make it fit. Pathetic.

Wanna talk about mounting? 10-32 is The Original telco size bolt, however square-hole with cafe-nuts are definitely the most flexible - and reparable if you strip a thread. I tend to make all my racks M6 (with Quadrex bolts), occasionally 10-32 just to use up the stockpile, but it annoys me. I also have 5-20, M5 and a few other sizes of bolts in my rack-bolt kit.

@jfmezei Raised floors are still very much a thing... no hard rule about how to arrange HVAC/power/data. Frankly it's religious.

I'm indifferent to AC power location and raised floors, but data and -48VDC should be up, and I'm a proponent of cold-aisle containment, rather than hot aisle containment.

If it's on slab, everything's from the top. Most facilities I'm in are simply hot/cold aisles, no containment.

I've yet to have an elechicken do the lighting the way I want in the facilities I design: vertical light strips on the wall at human-height. Sure - It's hard to look down the aisle, but it's really easy to see inside the rack.