Proper, clean cable management (howto)

Forrie:

Perhaps these will help.

John

Good links. I wish I had taken picture of the good and bad cabling I've come across, and done.

Some thoughts;

Buy a bunch of 1ft, 3ft, and 3ft patch cords. cableguys.com is good and cheap. (no relationship, etc)

Use this stuff as needed to span rows of racks or to get from the rack row to the wall.

For all the little cigar-box sized electronic boxes, I bought a desk organizer like this and put it in on a shelf in a rack;

Never stack anyting on anything else. You should always be able to move/remove any piece of equipment without disturbing anything else.

Give power distribution and cabling as much thought as the data. If you are anal as i am, you can get NEMA cables in 2ft and 3ft lengths. They are cheap. Newark Electronics (newark.com) sells short cables and the sell over the phone and always took my small ($100) orders. They *used to* send a huge catalog out to anyone that asked. Keep an assortment of old NEMA cords, sorted by length.

Wiremold makes rack-mounted power strips (p/n J06BOB20X-AM & others. They are annoyingly expensive, but there is a value to neatness.

Look at "power sticks" p/n 4810ULBC and others. Home Depot has them.

CabinetMATE Plug-In Outlet 4810ULBD Center - Ten outlets. 6' [1.8m] or 15' [4.6m] cord. Length 48" [1.2m]. Receptacle center-tocenter 4" [102mm].

I put two on each rack. One was masrked with red tape and plugged into the UPS and the other was just house power. Each piece of gear that needed UPS had red electrical tape around both ends of the NEMA cord.

Here's the WireMold catalog;

In the last place I built a computer room, I layed out a row of 7ft racks (about 8 rack widths). I needed new power circuits pulled from the panel, I had a 2x6 wood beam hung from the ceiling, the length of the row, above it. [*] Then I had the electrician run receptical boxes every couple ft on one side of the beam and cable mgmt loops on the other side. Neat. Cheap.

[*] Today I would probably use the metal equivilant of a wood beam.

Thanks for the URLs. I saw the "done right" article recently.

In our lab, they want to put the switches in the server racks themselves -- the rationale being to quickly pop cables/systems in and out, and temporary connections (ie: debugging) might result in cables on the floor, etc.

That's from my boss ;-) We're an educational/distance learning outfit; while we have some systems that will be constant and in production, we do tend to shuffle a little. I'm trying to clean that process up.

I would *prefer* that the switches be in the telco rack - but I can see some of his point.

That said I'm not sure how to properly dress the cabling in that scenario, other than the typical pull to the side and tie-down method. Pictures say more than words, so I've been looking for examples that way, too.

In one of the URLs pointed to from the "done right" article, it's not clear to me how they managed the power cables... it looks like an extra arm was fastened to the rack. Anyone know?

More suggestions, examples, advice, welcome. Thanks again.

Following-up to my own post, in the scenario where you have:

rack1 rack2 rack3

each with their own switches (assume separate networks). I wonder how to properly handle when rack1 needs to be connected to the network on rack3 also (ie: another NIC).

That sounds like a trap for a rats nest.

It all depends. Plan on cable channels up the side of each rack and across the top of entire row.

The basic issue that you're missing is that you should plan a perfect setup where no changes are ever needed. Or at least that's the way a log of management thinks.

The system that I have seen involved placing a patchbay in each rack, with X number of cables (and fiber) running to a central patching area.

Let X = max number of systems per rack x2 (to allow for dual NIC's), or even x3 (triple NIC or remote management console), plus some slop. I could see having 4x or even 5x the number of cables in some cases. (2-3 NICs, LILO, KVM, serial, etc.)

Pick a color code, and stick to it. Label everything. Put a serial number on each end of each cable.

You could stagger patchbays within racks, putting one at the top, another at the 2/3 up, another at 1/3, etc.

Allow space to each side of the rack rails, and install vertical cable management, and wiremold power strips. Velcro and lashing bars are your friends.

Some of the rackmount servers come with a cable arm for all the cables to allow the unit to be slid out of the rack, and unplugged from the front, or to allow access to the insides without unplugging.

Allow for more power than you think you will need, just remember that for every watt of heat that you radiate into the room, you need some means of removing from the room via A/C.

I like to have at least 2 circuits per rack, to allow putting dual power supplies on different circuits.

Not necessarily. If you have a properly configured network backbone, you can VLAN each rack switch and move ports between VLANs with ease. For instance if R1S1 (Rack 1 Server 1) needs to talk to R3S2, you just put them in the same VLAN. It becomes a network logic nightmare, but at least the cables look good!

Jeremy