Reliability in the Data Center

November 1, 2012


Keep the heart of the station beating strong

The data center

Whether you call it a tech center, master control, or simply the rack room, one thing is for sure: Every radio station needs a central location at which all studio feeds converge, and from which all STLs leave. Like other aspects of broadcasting, the purposes of this central hub have changed over the years. In the old days this room was occupied by members of the engineering staff, but today this room likely holds computers workstations and servers, and probably a motley collection of devices that all require LAN connections. This, of course, is in addition to the items we still associate with radio, like audio routers, STL transmitters, audio processors, and the like. For our purposes, let's call this room the data center. That's a little more in line with where we're headed anyway.

When computers started to show up in radio station studios generally they were just shoved inside the furniture somewhere (or behind it) and a big CRT monitor was perched somewhere. A mouse and keyboard were put somewhere close. Of course as time went on, more computers showed up in the studio, with their inherent problems: fan noise, heat generation, and of course the space they use. A solution to these issues was to locate the computers remotely, and of course master control was the obvious location. The need for KVM (keyboard, video, mouse) extenders was obvious.

Remote control

Belkin OmniView Cat-5 KCM extender

Belkin OmniView Cat-5 KCM extender


Belkin, for example, makes the OmniView Cat-5 KVM extender that allows users to control their computer or KVM switch from up to 300' away using (as you would expect) a single Cat-5 cable. The computer end of the system has local KVM ports that allow for local access to the remoted machine as well.

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Keep the heart of the station beating strong

Avocent Longview IP KVM

Avocent Longview IP KVM


Avocent offers Longview IP KVM, which allows a user's computer to be placed anywhere in the LAN (presumably in the data center). In addition to supporting keyboard, monitor and mouse, it supports devices as well, and optionally, VGA, DVI-I, DVI and dual DVI video.

Gefen USB 400

Gefen USB 400


If you need to remote a Mac into the data center, you might consider the Gefen USB 2.0 extender USB 400. This is a four-port USB extender that used fiber optics to connect the two ends -- and this particular one can go out 500 meters. This allows use of the mac keyboard, mouse and USB drives, which many producers insist upon. You'll still need to extend the monitor though by a different means. Another option is an all-in-one KVM extender that includes USB -- such as the Aten CE100 Mini Cat-5 USB KVM extender.

Aten CE100 Mini Cat-5 USB KVM extender

Aten CE100 Mini Cat-5 USB KVM extender


Of course there's an obvious problem with computers that are located in the data center -- no one has access to them, right? It won't take long before you'll need to reboot one of them, during something other than normal business hours. An IP power-switch is called for in this case, and quite a few companies make these but one you've likely heard of is Broadcast Tools. Its product is the AC Power Sentinel 2 Plus. This is a two-outlet device, connected to your LAN, with a built-in Web browser that gives the ability to connect to it remotely from anywhere, and to control the ac power independently on its outputs. Use it to switch ac voltage up to 240Vac, but the total current (for both outputs) can't exceed 10A. It also comes with a couple of inputs that can be connected to external temperature and humidity sensors, and it has two status inputs that can be used for local control of the power outlets (i.e., your trusty remote control, if you happen to locate it at a transmitter site). The device also supports SNMP.

Broadcast Tools AC Power Sentinel 2

Broadcast Tools AC Power Sentinel 2





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Keep the heart of the station beating strong

Opengear IP Power 9258

Opengear IP Power 9258


If two outlets aren't enough, then consider the opengear.com Opengear IP Power 9258. This unit also allows remote access via a browser for independent control of four ac power outlets (maximum current per outlet is 6A; total current limit is 15A). This device also has a console port, so it can be controlled externally via a modem and telephone line -- very handy if the remote device you need to boot is a DSL modem or perhaps a router or switch that has stopped and killed remote access to your LAN. The 9258 also supports SNMP.

Raritan PX Series

Raritan PX Series


Finally, if you need more than four outlets, you may want to consider the PX series of ac power controllers from Raritan. These not only allow control of the ac power outlets remotely, but it can also monitor the voltage and current on a per-outlet basis. The device can be configured to sequence the outlets if needed. There are many PX versions available, handling voltages from 100 up to 400Vac, and between 15 and 80A total (input current). These also have serial port access, and like the other devices mentioned, they support SNMP.

Blackbox ServSelect III KVM Switch

Blackbox ServSelect III KVM Switch


The other important thing to consider is this -- having multiple computers all in one location means you'll need a device that will allow you to look at each of them using the same keyboard, mouse and monitor -- more commonly known as a KVM switch. You could give two users complete access to eight different computers by using a single Blackbox ServSelect III KVM Switch, for example. This particular device supports PS2 keyboards and mice, provides 1600 by 1280 resolution, and can be cascaded to increase the number of computers to be accessed.

Another well-known manufacturer of KVM devices is Avocent. The first device I'll mention is the AutoView Analog KVM. This device supports USB and/or PS2 mouse and keyboard. It connects to each machine by way of a small dongle (for lack of a better description) that hangs on the back of said machine, and then connects to the KVM switch via a Cat-5 cable (up to 100' away). And yes -- you're thinking that (like the remote power switch) you'll want remote access via IP, right? In that case you would obtain the Digital KVM. That device has an onboard Web interface that allows two users remote access to any of the machines connected to the KVM switch. There's also a local-user port for access to the connected machines.

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Keep the heart of the station beating strong

Climate control

A room filled with computers obviously needs air conditioning. If you are in the process of building a new facility, you may not have all that much input on which units get chosen (aside from giving electrical consumption figures to your MEP engineer). However, due to the 24/7 nature of systems such as this, and your 24/7 need to know what is going on inside the data center, make sure you look at the BACnet and SNMP capabilities of any A/C units that are specified. BACnet is a communications protocol that allows devices such as A/C units to talk directly with BMS systems, and many manufacturers support it; take a look at this Web page for more specifics: bacnet.org/Gallery/index.html. Liebert, Trane, and Carrier are three well-known manufacturers on that list.

SNMP is the communications protocol that will allow you to keep track of what is going on via an SNMP manager. Just because a manufacturer supports BACnet doesn't mean that there is SNMP support. The way to find out is to take the specified manufacturer, then the model number of the LAN interface card that fits in it. Check its specifications then. All is not lost though if there is no support for SNMP; several companies make BACnet-to-SNMP converters. Control Solutions is one. Another is Chipkin.

Power control

Alternate power sources are also very important for the 24/7 operation of a data center. There are two types of power outages to be concerned with. First, the inevitable "momentary" that is just long enough to let power supplies sag -- but not long enough to bring on the emergency power. And, of course, those that are. The first is handled by a UPS -- and the second by an emergency power source. Let's talk about both of these.

UPSs have become important since more and more computers have shown up at the radio station because, as we all know, they don't like momentary power hits. There are a couple of considerations aside from the power handling capability:
■ Will there be a UPS per rack, or a large one that is the source for all racks?
■ Battery powered (the usual choice) or perhaps flywheel powered?

If you opt for a single, large UPS then, again, you'll be providing information to your MEP engineer about the load size (which pretty much is what it is, right?) and the length of time you want to be able to hold everything up -- in other words, how long the UPS can power the data center on its own. Clearly this is a budget issue -- not only in the cost to acquire the unit, but to install it, and to maintain it. Large capacity means lots of batteries and higher maintenance costs down the road. And don't forget to build-in extra capacity. We all know more computers get added as time goes on.

The other choice -- putting rack-mount UPSs in where they are necessary -- has its advantages and disadvantages as well. The primary advantage is expense. You buy and install a rack-mount UPS as needed. With one large UPS you focus your maintenance attention on it, of course -- but with smaller unit scattered about, you'll need to keep track of every individual unit. To me that is a disadvantage. As far as battery expense goes -- it's going to depend upon the size and number of batteries in a large UPS -- which will all get changed at once -- versus the cost dozens and dozens of smaller lead-acid cells.

You will find your job of maintaining UPSs is much easier if you always buy the network interface adaptor that comes with the unit. This will give you browser access -- so you can see what is going on from anywhere -- or perhaps even SNMP support, so that you can monitor the health of all the various units on a 24/7 basis. There are many manufacturers from which to choose when it comes to UPSs: Emerson (Liebert), APC, Toshiba, and Mitsubishi are some of the better known ones. For (relatively) small UPSs I'd like to bring one more brand to your attention -- Falcon Electric. The company specializes in double-conversion types -- in other words, ac to dc, then back to internal ac sine-wave generation. This type of online UPS eliminates power line transients very effectively -- especially compared to a unit that passes the ac through -- only switching to battery power as necessary.

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Keep the heart of the station beating strong

Another option for UPSs is the flywheel type. In this device, energy is stored in the rotating flywheel, as opposed to batteries. The obvious advantage here is that there are no batteries to replace as time goes on. The obvious disadvantage is that there is usually a limited amount of time this type can maintain the load. This type really only covers you while your emergency source gets ready to go. And just because there are no batteries doesn't mean there is no maintenance cost -- for example, in the flywheel type, you will need to change the bearings after a certain number of hours. That's not an inexpensive proposition. Some well-known manufacturers of this type are Active Power and Caterpillar.

An emergency power source is a requirement for any data center that intends to maintain 24/7/365 operations. The obvious choice for that is a generator set. Again, if you're building a new facility, you'll tell your MEP engineer about the load requirements. Sizing of the set isn't the only thing to consider, though -- fuel source is another, as are fuel storage and availability. There are many factors to consider when it comes to selecting the fuel source. Here is a simple Web page that has all the advantages and disadvantages conveniently laid out for you: generatorjoe.net/html/genfuel.html. Propane and natural gas are alternatives to diesel.

Of course you'll want to have remote access to your generator set. Cummins, for example, has a feature called PowerCommand iWatch. This browser-based monitoring system allows you to supervise and control generators (and transfer switches) from anywhere. In addition to Web access it provides alarm notifications, real-time data collection, data retention, and report generation.

Kohler is another well-known manufacturer of generator sets. Its remote access is provided by way of the generator controller system called Decision Maker. A PC runs software (called Monitor III) that communicates with the controller, and this connection can be done serially (or dial-up modem) or via a LAN connection through a Modbus/Ethernet converter.

Caterpillar has a product known as ECMP for monitoring and control of their generator sets, and they also provide ECMP remote monitoring software that will run on a PC that talks with the control panel via a 10baseT Ethernet connection. Like the Kohler system, you would have to remotely access the computer that runs the vendor-specific software.

Alternatives to generator sets are few; one is the fuel cell. Most of the fuel cells out there top out at 5kW of production -- probably of little use for a data center. On the other hand, there is. Bloom Energy. Bloom is producing solid-oxide fuel cell (the ES5400) for the 100kW level (480V/3-phase). Fuel sources are either natural gas or directed biogas. Bloom remotely manages the device, by the way; they give you access to a website that shows its performance.

Radio stations have changed much over the years -- and so have data center (or master control room) requirements. It takes an amazing amount of resources to maintain large groups of computers.


Irwin is transmission systems supervisor for Clear Channel NYC and chief engineer of WKTU, New York. Contact him at doug@dougirwin.net.



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