How do you organise the cables in your racks?

Solution 1:

Here's what I do

Label each cable
I have a brother P-Touch labeler that I use. Each cable gets a label on both ends. This is because if I unplug something from a switch, I want to know where to plug it back into, and vice versa on the server end.

There are two methods that you can use to label your cables with a generic labeler. You can run the label along the cable, so that it can be read easily, or you can wrap it around the cable so that it meets itself and looks like a tag. The former is easier to read, the latter is either harder to read or uses twice as much label since you type the word twice to make sure it's read. Long labels on mine get the "along the cable" treatment, and shorter ones get the tag.

You can also buy a specific cable labeler which provides plastic sleeves. I've never used it, so I can't offer any advice.

Color code your cables
I run each machine with bonded network cards. This means that I'm using both NICs in each server, and they go to different switches. I have a red switch and a blue switch. All of the eth0's go to red switch using red cables (and the cables are run to the right, and all eth1's go to the blue switch using blue cables (and the cables are run to the left). My network uplink cables are an off color, like yellow, so that they stand out.

In addition, my racks have redundant power. I've got a vertical PDU on each side. The power cables plugged into the right side all have a ring of electrical tape matching the color of the side, again, red for right, blue for left. This makes sure that I don't overload the circuit accidentally if things go to hell in a hurry.

Buy your cables This may ruffle some feathers. Some people say you should cut cables exactly to length so that there is no excess. I say "I'm not perfect, and some of my crimp jobs may not last as long as molded ends", and I don't want to find out at 3 in the morning some day in the future. So I buy in bulk. When I'm first planning a rack build, I determine where, in relation to the switches, my equipment will be. Then I buy cables in groups based on that distance.

When the time comes for cable management, I work with bundles of cable, grouping them by physical proximity (which also groups them by length, since I planned this out beforehand). I use velcro zip ties to bind the cables together, and also to make larger groups out of smaller bundles. Don't use plastic zip ties on anything that you could see yourself replacing. Even if they re-open, the plastic will eventually wear down and not latch any more.

Keep power cables as far from ethernet cables as possible Power cables, especially clumps of power cables, cause ElectroMagnetic Interference (EMI aka radio frequency interference (or RFI)) on any surrounding cables, including CAT-* cables (unless they're shielded, but if you're using STP cables in your rack, you're probably doing it wrong). Run your power cables away from the CAT5/6. And if you must bring them close, try to do it at right angles.

Edit I forgot! I also did a HOWTO on this a long time ago: http://www.standalone-sysadmin.com/blog/2008/07/howto-server-cable-management/

Solution 2:

I saw this because of Matt's blog post, I responded to that, but here are some highlights.

Keep power cables as far from ethernet cables as possible

This is dependent on your site, but the worst cabling disasters I've dealt with are when people slavishly run power cables and ethernet cables up and down the sides of the rack. It seems like a great idea in theory, but the practice is a giant knot of either power or ethernet inside the rack post.

The best way I've found to combat this problem is to run ethernet down the center of the rack, rather than the sides.

One thing I forgot to mention before is that ethernet cables and power cables are different. That means they are run differently, have different lifetimes and different uses.

Patch Panels These are your friend. If you have a separate networking group and they don't use patch panels, it is because they don't know how to use them.

Patch Panels -- The Bad Yes, they take up space in your rack, yes they limit the amount of available ports per rack. Putting them in is more work. I will also admit they are not appropriate for every site.

Patch Panels -- The Good Tracing cable runs of 6 feet or less is exponentially easier than tracing cable runs of 12 feet or more. Adding in new equipment is easier, no more fishing cables through 15 different runs. This can limit the amount of crap that gets shoved into one rack (sometimes this is good).

It is a fact of life that servers move frequently comparative to other datacenter equipment. All your old cable drops just add to mess you have to deal with. Since power cables are confined to the rack and can always be reused, this keeps the clutter buildup down.

Most of the frequently cited bad issues with patch panels can be mitigated through planning appropriately.

Raised Floors Can still be a good thing in some cases. NEVER put network drops under a raised floor unless you hate your coworkers and plan to leave soon. If you have a raised floor only use it to run power cables.

Ladder Racks Overhead cable runs are the only way to preserve your sanity or blood pressure. This is especially true if you don't use patch panels.

Solution 3:

I think this a very similar question to these:

Cable Management Policy
How to keep your physical server environment manageable

The only thing I have to mention, use velcro tie wraps.

Solution 4:

As far as what to label the cables with - I would stay away from anything specific like hostnames or mac addresses, since the cables/switch ports will likely be re-purposed over time.

But DO label them with something - numbers seem the obvious choice.

Label both ends the same, and ensure there are no duplicates. This makes tracing cables a whole bunch easier, and alleviates much of the concern of bundling a bunch of cables together into a neat run. We even label our short (1 foot) cables, and then bundle them into bunches of 10-20 - and it makes it MUCH easier to identify which cable is which.

Another option would be colored cables - but that gets to look messy.