Server Cable Management (SM and others)

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Cutha

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Sep 24, 2016
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Hi,

Please forgive my general ignorance as I have limited exposure to servers.

I have 4x SuperMicro 2U servers (6027R-ER12N) and some other generic cases. At work I have only ever setup Dell servers and I like the cable management arm that we order with those servers.

Is there such a thing as a generic cable management arm that I can use with various types of racks? I am about 10x over my server budget so the cheapest option that works is best for my marriage.

Failing an arm, do you guys have any other suggestions? I went to work on my rack yesterday and nearly cried at the horror when I opened up the back door.

Thanks.
 

K D

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Dec 24, 2016
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Someone on the forums was looking into this earlier and gave up. I think it was @BLinux but I may be wrong.
 

BLinux

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Jul 7, 2016
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I don't know about "generic" cable management arms. I looked into the Supermicro ones, and found that they were not really tested in the field and don't work. Don't buy the Supermicro ones. I have a thread around here with the details of what i found out.

If you find some sort of "generic" solution, you'll need to take into consideration the following:

1) when fully retracted, does it leave enough room to actually route the cables you want to route?
2) when fully retracted, will it obstruct your ability to hot-swap PSUs?

I ended up leaving a 1U gap between my servers, and attached a lacing support bracket at that space just below the server. this allows me to hot-swap the PSUs. i then zip tied the cables, leaving enough slack to pull the server out. I have to slide the server in/out carefully, but it sort of works. Unfortunately I don't have anything better at the moment.

This is certainly one area where Supermicro server products are lacking when compared to Dell or HP.
 

Evan

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Jan 6, 2016
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Having said this I find it much cleaner not to use cable arms and less air resistance as well. Only thing is must label cables well as they have to be removed to slide the server out but happens so infrequently and nothing outside of drives and psu are generally hot swapable so not usually a big deal.
 

Terry Kennedy

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Jun 25, 2015
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I ended up leaving a 1U gap between my servers, and attached a lacing support bracket at that space just below the server. this allows me to hot-swap the PSUs. i then zip tied the cables, leaving enough slack to pull the server out. I have to slide the server in/out carefully, but it sort of works. Unfortunately I don't have anything better at the moment.
I do something similar, but I don't use rack rails and the chassis sits on the rear bracket:



I don't provision extra-long cables to the chassis because I don't want it running when I am pulling it out - too much bouncing of disk drives, etc.

I also modified tthe front chassis brackets to add 2 additional mounting holes on each side, since the single hole under the handle was intended for a simple retaining thumbscrew, not as the sole support for the front of the chassis. Details here. Sample pic (unfortunately rotated 90 degrees):

 

BLinux

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Jul 7, 2016
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I would not use cable management arm
They impede airflow, and that there are better 3rd party cable management solutions that accomplish the same thing. I admit, they make it faster to pull hardware out of the rack, but in my opinion, it's not worth the hassle and heat.
those issues are mitigated if the cable management arm is designed correctly; unlike the supermicro ones. the well designed ones are often offset to the rear of the rack mounting rails by several inches, not only does this allow one to properly route cables into the I/O panel of the motherboard, PCI slots, and PSU, but it also gives plenty of clearance for the exhaust air to vacate. (assuming front to rear air flow)

the need to slide out and open the chassis easily varies by chassis design and use case. i don't think most people will be hot-pluggin PCI cards, CPU, or RAM - so those type of cases it doesn't matter. replacing hot-plug fans is a valid use-case for a simple operation that shouldn't require down time. for a supermicro 846 chassis, if the OS boot drives are installed on the interior, then replacing a failed SSD to restore the mirror of a boot drive would be another use-case where ease of sliding out the server makes sense. doing maintenance on a server without having to unplug cables aside (and potentially shutting it down), in a lab environment, where you might be testing out a lot of equipment and swapping parts frequently, it does make a difference to be able to pull the server out and push it back in quickly without having to unplug cables each time. so, for me, the convenience factor matters and hence why i was looking for a cable management arm solution, but unfortunately did not find one and I'm making due with the solution mentioned above.
 

aero

Active Member
Apr 27, 2016
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I also am strongly against cable management arms, granted I'm not familiar with super micros, only Dell, HP, and IBM.

I've never run across a scenario where I've needed to pull a server while still powered on, and don't mind temporarily disconnecting cables.

Of course I don't have any cool top-loading disk arrays either.

Most important in my opinion is proper vertical cable management in the cabinet, and deep enough cabinet to provide room for cable management and zero U pdus.

Oh... And while on the topic of cable management, what masochist designed the rj45 cable jacket that full envelops the tab and is too hard to depress with your fingertip?! If I need to use my ID badge or other macgyver tactic to remove a cable it's not a good thing.
 
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Terry Kennedy

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Most important in my opinion is proper vertical cable management in the cabinet, and deep enough cabinet to provide room for cable management and zero U pdus.
Yup. And a plan for what cables go where. Here's a quick (older) pic of the back of my home server racks. On the left side of the rearmost set of rails (there are 4 pairs of rails in each cabinet) there are white nylon standoffs which are used for power cables, console serial port cables, and the occasional other things (the thin gray wire is a phone cable that runs to the phone blocks up top, and then down and out the bottom of the cabinet to a telephone on the desk to the side of the cabinets). The right side has vertical cable management rings for network cables, console (VGA + USB or PS/2) cables, and most phone cables. In my case, most of my equipment had power cords to the left and network cords to the right, so that cabling layout made the most sense.



Oh... And while on the topic of cable management, what masochist designed the rj45 cable jacket that full envelops the tab and is too hard to depress with your fingertip?! If I need to use my ID badge or other macgyver tactic to remove a cable it's not a good thing.
That was originally intended to keep the gorillas from ripping the tabs off the plugs and/or yanking the cable jacket out of the plug. Panduit makes (made?) some after-the-fact covers which folded over and snapped onto the connector, and had an impossibly small white paper ID card and clear plastic cover that you could go nuts trying to assemble. I use some soft molded plastic ones that you have to put on when you're making the cables, and I only put them on the device ends, not on the switch ends (they're too fat and you can't use a row of them on most switch ports these days). I forget who makes them - they had a minimum order of like 10,000 pieces (for some silly low price) and they came in bags of 500. I still have cartons of them around here somewhere.

Those things don't annoy me as much as companies that build products where the connector tab is right next to some piece of the chassis or other obstruction, where you can't remove even a "naked" cable without some creative fiddling. The manufacturers should know better...
 

Caleb

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Nov 16, 2015
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Is the preferred method for cable management still lacing bars with zip ties?
 

fmatthew5876

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Mar 20, 2017
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I just use lots of velcro ties to bind the cables together into one thick rope of cable. I make it just long enough that I can slide the box all the way out on the rails for maintenance. The end of the rope is bound to the rack with more velcro ties, keeping the length fixed.

My half height rack in my living room isn't deep enough for cable management arms. They cost and are kind of a nuisance anyway. Fat arms could also restrict airflow if you have little space.
 
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