Posts Tagged 'Debate'

August 22, 2013

Network Cabling Controversy: Zip Ties v. Hook & Loop Ties

More than 210,000 users have watched a YouTube video of our data center operations team cabling a row of server racks in San Jose. More than 95 percent of the ratings left on the video are positive, and more than 160 comments have been posted in response. To some, those numbers probably seem unbelievable, but to anyone who has ever cabled a data center rack or dealt with a poorly cabled data center rack, the time-lapse video is enthralling, and it seems to have catalyzed a healthy debate: At least a dozen comments on the video question/criticize how we organize and secure the cables on each of our server racks. It's high time we addressed this "zip ties v. hook & loop (Velcro®)" cable bundling controversy.

The most widely recognized standards for network cabling have been published by the Telecommunications Industry Association and Electronics Industries Alliance (TIA/EIA). Unfortunately, those standards don't specify the physical method to secure cables, but it's generally understood that if you tie cables too tight, the cable's geometry will be affected, possibly deforming the copper, modifying the twisted pairs or otherwise physically causing performance degradation. This understanding begs the question of whether zip ties are inherently inferior to hook & loop ties for network cabling applications.

As you might have observed in the "Cabling a Data Center Rack" video, SoftLayer uses nylon zip ties when we bundle and secure the network cables on our data center server racks. The decision to use zip ties rather than hook & loop ties was made during SoftLayer's infancy. Our team had a vision for an automated data center that wouldn't require much server/cable movement after a rack is installed, and zip ties were much stronger and more "permanent" than hook & loop ties. Zip ties allow us to tighten our cable bundles easily so those bundles are more structurally solid (and prettier). In short, zip ties were better for SoftLayer data centers than hook & loop ties.

That conclusion is contrary to the prevailing opinion in the world of networking that zip ties are evil and that hook & loop ties are among only a few acceptable materials for "good" network cabling. We hear audible gasps from some network engineers when they see those little strips of nylon bundling our Ethernet cables. We know exactly what they're thinking: Zip ties negatively impact network performance because they're easily over-tightened, and cables in zip-tied bundles are more difficult to replace. After they pick their jaws up off the floor, we debunk those myths.

The first myth (that zip ties can negatively impact network performance) is entirely valid, but its significance is much greater in theory than it is in practice. While I couldn't track down any scientific experiments that demonstrate the maximum tension a cable tie can exert on a bundle of cables before the traffic through those cables is affected, I have a good amount of empirical evidence to fall back on from SoftLayer data centers. Since 2006, SoftLayer has installed more than 400,000 patch cables in data centers around the world (using zip ties), and we've *never* encountered a fault in a network cable that was the result of a zip tie being over-tightened ... And we're not shy about tightening those ties.

The fact that nylon zip ties are cheaper than most (all?) of the other more "acceptable" options is a fringe benefit. By securing our cable bundles tightly, we keep our server racks clean and uniform:

SoftLayer Cabling

The second myth (that cables in zip-tied bundles are more difficult to replace) is also somewhat flawed when it comes to SoftLayer's use case. Every rack is pre-wired to deliver five Ethernet cables — two public, two private and one out-of-band management — to each "rack U," which provides enough connections to support a full rack of 1U servers. If larger servers are installed in a rack, we won't need all of the network cables wired to the rack, but if those servers are ever replaced with smaller servers, we don't have to re-run network cabling. Network cables aren't exposed to the tension, pressure or environmental changes of being moved around (even when servers are moved), so external forces don't cause much wear. The most common physical "failures" of network cables are typically associated with RJ45 jack crimp issues, and those RJ45 ends are easily replaced.

Let's say a cable does need to be replaced, though. Servers in SoftLayer data centers have redundant public and private network connections, but in this theoretical example, we'll assume network traffic can only travel over one network connection and a data center technician has to physically replace the cable connecting the server to the network switch. With all of those zip ties around those cable bundles, how long do you think it would take to bring that connection back online? (Hint: That's kind of a trick question.) See for yourself:

The answer in practice is "less than one minute" ... The "trick" in that trick question is that the zip ties around the cable bundles are irrelevant when it comes to physically replacing a network connection. Data center technicians use temporary cables to make a direct server-to-switch connection, and they schedule an appropriate time to perform a permanent replacement (which actually involves removing and replacing zip ties). In the video above, we show a temporary cable being installed in about 45 seconds, and we also demonstrate the process of creating, installing and bundling a permanent network cable replacement. Even with all of those villainous zip ties, everything is done in less than 18 minutes.

Many of the comments on YouTube bemoan the idea of having to replace a single cable in one of these zip-tied bundles, but as you can see, the process isn't very laborious, and it doesn't vary significantly from the amount of time it would take to perform the same maintenance with a Velcro®-secured cable bundle.

Zip ties are inferior to hook & loop ties for network cabling? Myth(s): Busted.

-@khazard

P.S. Shout-out to Elijah Fleites at DAL05 for expertly replacing the network cable on an internal server for the purposes of this video!

April 14, 2009

EVA, Cloud Computing, and the Capex vs. Opex Debate

So far in 2009, there’s been a fair amount of discussion pro and con regarding the financial benefits (or lack thereof) of cloud computing. It’s very reminiscent of the whole “do-it-yourself” or “outsource it” debate. Blog posts like this and articles like this are samples of the recent debate.

One thing I have not yet seen or heard discussed regarding cloud computing is the concept of EVA, or Economic Value Added. Let me add at this point that EVA is a registered service mark of EVA Dimensions LLC and of Stern Stewart & Co. It is the concept of economic income instead of accounting income. SoftLayer subscribes to software from EVA Dimensions LLC. Get more info here.

For you to buy into the premise of this post, you’ll have to be sold on EVA as a valuable metric. Bottom line, EVA cleans up the distortions of GAAP and aligns all areas of the business so that more EVA is always better than less EVA. Most other metrics when pushed to extremes can actually harm a business, but not EVA. Yes, even bottom line GAAP net income when pushed to an extreme can harm a business. (How that can happen is fodder for another blog post.) Several books have been written about EVA and its benefits, so that’s too much to write about in this post. This is a good summary link, and for more info you can Google it on your own. And if you do Google it on your own, be warned that you may have to wade through links regarding Eva Longoria and/or Eva Mendes .

Part of the Cloud computing debate revolves around “capex vs. opex.” Specifically, this involves paying for IT infrastructure yourself using capital expenditures (“capex”) or employing Cloud computing and buying IT infrastructure with operating expenditures (“opex”). Geva Perry recently said, “There is no reason to think that there is a financial benefit to making an OpEx expense vs. CapEx expense. Period.” I disagree. When you look at this in terms of EVA, whether you use capex or opex can make a big difference in creating value for your business.

Let’s look at the effect of switching capex to opex on EVA. Coca-Cola is a company that employs EVA. Years ago, they decided to ship their beverage concentrate in single-use cardboard containers instead of reusable stainless steel. This made GAAP measures worse – profit and profit margins actually went down. But EVA went up by making the move from capex to opex. How can this be? Grab something caffeinated and check out some numbers here if you dare.

OK, that’s all fine. But how would shifting IT spending from capex to opex affect EVA? Glad you asked. Last summer, I modeled some full-fledged financials to illustrate financial benefits of outsourcing IT vs. doing it yourself. I’ve taken those and added the EVA calcs to them. Take another swig of caffeine and check them out here and here.

Assuming that EVA is a worthwhile metric (and I think it is), moving capex to opex is possibly a very good financial decision. Any questions? As always, your mileage may vary. Model carefully!

May 7, 2008

The Great Debate

Who would win in a fight to the death between a Grizzly Bear and a Great White Shark?

Yes, we here in SLales, particularly Daniel and myself, have these types of serious debates quite often. Now before you get all riled up about how this would never happen and there’s no way these two would ever even meet, etc, etc, hear me out folks. Daniel said it best during one of our many debates about this important issue:

“I win the lotto and I’m putting this show on Pay-Per-View.... greatest show on earth.”

IIIIIIIIIIIn the red corner weighing in at 5,000lbs, laying 20 feet long – SHARKY! AAAAAAAnd in the blue corner weighing in at 1,500lbs and standing 8 feet tall – GRIZZLY!

The setting would be similar to the UFC Octagon, only twice the size, instead of a cage it will be a solid metal octagon and filled with 4 feet of water so the Shark can maneuver and so can the Bear. Both animals are fully grown adults - the Shark is a female, the Bear is a male - predatory in nature and very aggressive.

My contention would be that the Great White wins this battle to the death for a few reasons:

  1. The Great White Shark has been dubbed “an efficient killing machine” on several occasions by many scientists and experts.
  2. This ain’t no Salmon Grizzly; this is 20ft and 5,000lbs of fury coming for YOU Bear!
  3. Sharky is HUGE, more than double the size of Grizzly.
  4. Sharky has rows and rows of teeth that are easily replaceable in a fight to the death, Grizzly has one set and that’s it.
  5. Great White Sharks are notorious for their thick skin; the bear doesn’t stand a chance with his teeth and claws.
  6. Yes, Grizzly will be more maneuverable, however one bite from Sharky and he’s done.
  7. There is a certain 80's rock band named after Sharky, none for Grizzly.

What’s you guys’ take on the outcome here, do you think Sharky or Grizzly would win?

Daniel, I await your side of the argument sir!

-Michael

***The views and expressions of these events are completely fictional and meant for entertainment purposes only. ***

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