Bringing Home Baby: Physical Planning for a New AS/400

IBM i (OS/400, i5/OS)
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The physical aspects of planning for a new AS/400 are as important as the software you put on it. Take a little extra time up front to determine where your new AS/400 will be placed and how you will connect your users to it. This article will help you begin the planning process.

After months of financial and political maneuvering, you’ve just gotten word that you can place the order for a new AS/400. As you leisurely stroll back to your office, mentally congratulating yourself on a job well done, you wonder what you’re going to do with all those old Commodore 64s you had networked together, composing your previous computer system. “Oh well,” you think. “They’ll probably bring top dollar at an auction. It’ll at least free up some space on the user’s desktop.” Suddenly, you stop, slap yourself on the forehead, and exclaim, “Hey! Wait a second! Where am I going to put this new computer?!?”

OK, maybe that scenario is a bit dated. What’s more likely to happen is this: You get approval to add additional AS/400s to your current network, or your company is one that has been using nothing but PCs for years and has now decided to move to the more stable (and scalable) AS/400. Whatever the reason, whether you’re adding your first or your 15th AS/400 to your business, you need to think about the physical aspects of installing the hardware at your site.

It’s a New Ball Game

When you buy a new PC for your office, most of the planning consists of where to purchase it. Usually, you know why you’re buying it and who’s going to get it, so, other than that, there’s just not a whole lot of planning involved. The most you have to worry about is whether there’s a handy plug-in for the surge protector and whether the user likes the monitor on the left or the right side of the desk. Not too tough.

That’s not the way it is with IBM’s premier computing platform. When you buy a new AS/400, you find yourself in a whole new ball game. You can’t just run down to your

nearest electronics outlet store and grab one off the shelf. Even if you could, putting it onsite is a lot more involved than simply finding a handy wall outlet. With that in mind, this article takes a look at some of the more common considerations involved in planning for and installing a new AS/400 at your site.

There are four general steps you will take as you plan for a new AS/400: Investigation, Decision, Shipment, and Installation. Any or all of these steps may be performed by you, by IBM, or by a knowledgeable outside agency, such as your local IBM Business Partner. In this article, I’m going to look at only the first step, Investigation, because that’s the point at which you make all the important “physical” decisions.

The investigative phase of planning for a new AS/400 consists of determining such factors as which system model you want and what features you want with it, as well as the physical layout of the proposed site for your new AS/400. In addition, it is during this phase that you begin to think about power requirements, cabling, networks, and environmental factors, such as temperature and humidity.

Size Does Matter

I’m not going to spend much time talking about which system model and features you want. There are more factors that affect this decision than I can even begin to cover here. However, which model and which features you choose do make an impact on the physical planning for your new AS/400. As far as which model of AS/400 to choose, the most important thing you need to be concerned about is its physical size. In years past, size was an even more important issue than it is today because the rack(s) the AS/400 came in was (were) so large. This has become less of a problem in recent years as the size of the AS/400 has shrunk in height and width while its processing power has grown. Despite its more diminutive stature, however, the size still controls where the new box will find its final resting-place.

You should obtain the specifications for the AS/400 model you are purchasing as well as any additional components it may come with, such as additional DASD or external tape drives. The AS/400 ranges in size from as short as 24 inches for the model 170 to as tall as 62.1 inches for the model 650. Add to that the height and width of an expansion tower, and you can quickly run into space problems. Take a look at Figure 1 for the physical dimensions of a model 650 that also has a companion expansion rack. You can get an immediate idea of how much room you’re going to need for the AS/400 by looking at this figure. For a complete list of dimensions of the various system configurations, including external devices such as the expansion tower, refer to Chapter 2 of the IBM AS/400 Physical Planning Reference, “Physical Summary for System Model Towers and Devices”.

When you’re planning for the physical location of your new AS/400, you must also ask yourself the following questions:

1. Do you need a separate room for the AS/400 and its peripherals (e.g., system printer, console, etc.)?

2. Will the room where you store the AS/400 be used for anything else that might interfere with the machine’s operation? (For example, will your AS/400 be placed in a high-traffic area where its power switches, power cords, or communication lines could inadvertently be tampered with?)

3. If you plan to put the AS/400 in a room that’s already being used for some other purpose, will there be enough physical space for routine maintenance? Keep in mind that, at some point, you or the IBM Customer Engineer (CE) will probably need to work from the back of the AS/400, so you need to make sure there is enough room to work comfortably. One way to accommodate this space crunch is to determine if the AS/400 box is small enough that you can easily pull it out far enough to get to the back of it. This is generally feasible with the smaller models, such as the 150 or the 600.

4. Will you have enough space around your AS/400 for all the attached cables and power cords?

5. Will you need an additional storage rack for such items as modems, a Multistation Access Unit (MAU), and Ethernet hubs?

6. Will the location you choose for your AS/400 have adequate all-around ventilation? You don’t want to stick it under a desk against a wall because, if you do, you run the risk of having the machine overheat and cause a fire.

7. Do you need special flooring that allows you to run all the cables underneath the floor? This type of flooring was common in computer rooms of the past but is not necessarily required today; however, a raised floor does allow for a tidier computer room.

More Power!

Once you’ve determined where your AS/400 will physically fit, you need to find out if you have the correct electrical connections in that location. Once again, you should refer to either the Physical Planning Reference manual or the specs provided to you by your IBM representative so you can determine the power requirements. Such a determination may not be as straightforward as you think. Consider these questions before you designate a permanent site for your AS/400:

1. Does your model of AS/400 use the standard 110-volt (household) current, or does it require a 220-volt connection?

2. Does this model of AS/400 come with a special lock plug or a standard three- prong ground plug?

3. You will need to purchase and install an uninterruptible power supply (UPS) as a battery backup for your AS/400. Do you have the proper wiring in place to handle the increased load?

4. Are you able to contract with an electrician to install the appropriate electrical hardware in time for your AS/400’s arrival?

Stormy Weather

Before you lock yourself into a location for your AS/400, you’d better get a weather report for the room. If the air is too damp, you may be able to install a dehumidifier to pull some of the moisture out of the air. If the dehumidifier doesn’t do the trick, you had better find a new location. Electronics and moisture are a volatile mix. On the other hand, if the air is too dry, you run the risk of exposing yourself and your equipment to static electricity, and this is a major no-no. The small, harmless shock you give to yourself or others when you scrape your feet across a rug can easily fry a circuit board when you inadvertently forget to ground yourself and touch sensitive computer equipment. Dry air can be deadly for your AS/400. You can counteract dry air by installing a humidifier. If you do, you want to monitor its use to ensure that you are not pumping too much moisture into the room.

Beyond that, you need to ensure that you have an adequate cooling system installed. The AS/400 and its peripherals generate a lot of heat. Ideally, you should maintain a consistent 70 degrees Fahrenheit in the room. This temperature is ideal for both the equipment and the humans who work with it.

While you’re checking out the humidity and air conditioning, you should also consider fire safety. It used to be common, especially with the larger mainframe shops that had a room devoted exclusively to computer equipment, to install an expensive Halon fire extinguishing system in the computer room. This elaborate system was ideal for smothering electrical fires without damaging sensitive electronic equipment or killing an occupant of the room who might become trapped. The Halon system accomplished this by producing a chemical that disrupted the ignition capability of fire, thereby causing a fire to extinguish itself. This system worked great, but there is one major drawback to it. It is now illegal to manufacture Halon in the United States and other industrialized nations because of Halon’s ozone-depleting characteristics, although there are many vendors who still sell and service Halon systems.

If you don’t want to damage the environment, don’t despair; alternatives to Halon are available. Most fire suppressant manufacturers, electrical supply shops, and even some

of the larger home improvement stores sell chemical fire suppressants designed to put out an electrical fire without harming the electronics. These fire extinguishing systems come in a variety of sizes, from as small as a handheld unit to systems large enough to handle fires anywhere in the building.

Send It by Western Union

Once you’ve ironed out all the problems with the location for your new AS/400 (space, environment, safety), you need to think about how you are going to get the data from the hardware to the users. If you are installing a new system in a new building, you may have to install a completely new cable infrastructure. If this is the case, you should consider installing a fiber optic network. Such an installation would allow you to take advantage of the high bandwidth and speed available to you with fiber optics while at the same time positioning you to be ready for any new technology coming down the road. As of this writing, fiber optics provides the cleanest, fastest data transfer capability of any cabling system. The downside is that fiber optics is expensive.

If it’s not in your budget to go for the very best, you can compromise with the next to best: Category 5 (Cat5) wiring. Cat5 is a series of wires, twisted and shielded in such a way as to provide you with fast, reliable data transmission. While Cat5 cable cannot reach the speeds or bandwidth of fiber optics, it is capable of meeting the needs of most installations. Cat5 wiring can typically transmit data reliably at speeds of 100 megabits per second (Mbps). It also has the advantage of being relatively inexpensive. Cat5 wire is shielded from electrical interference, which makes it suitable for installation in most areas.

If you’re looking for an even less expensive alternative, there’s always twisted-pair wiring. Twisted-pair wiring is used in standard telephone wire. It contains four individual sets of wires within its unshielded casing. Twisted-pair is very inexpensive, but because it is unshielded, it is susceptible to outside electrical interference. Outside electrical interference can be something as simple as an exit sign installed too close to the wiring or as complex as your electric company’s nearby power substation, and it can cause data transmissions to degrade and become unusable.

Your last wiring alternative is to use twinaxial cable. Twinaxial cable consists of two heavy, tightly twisted copper wires that run parallel to each other inside a heavily shielded wrapping. The entire complex then sits inside a heavy, pliable rubber casing. Twinaxial cable used to be the only way to attach devices to the AS/400 or its ancestors. With the advent of twisted-pair and the other cabling alternatives, though, twinax has taken a bit of a back seat. However, IBM has recently announced improvements in the AS/400’s support of twinax, boosting data transmission speeds to 2 Mbps. This may be an acceptable alternative for certain device locations in your shop. You’ll need to examine the proposed uses of those devices that could potentially use the twinax cable to see if this choice would be a good fit.

Before you decide on a cable solution, get the specs on it from your cabling vendor. You need to decide where you will have devices hardwired to your AS/400 and know the physical distance from those devices to the CPU. There are limits to how far the data can be transmitted to and from the AS/400 before it needs to be “boosted.” In addition, for some cabling solutions (such as twinax), after you reach a certain distance, you’ve passed the point of diminishing returns, where the data can no longer be reliably boosted to its destination. Plan the layout of your users and talk with your vendor before you choose a cabling solution. What will most likely happen is that you end up with a mixture of two or more of the available cable possibilities.


OK, you’ve found a place to put your AS/400, and you’ve come up with a way to wire your workstations. The only thing left is to decide what type of workstations you are going to let your users have. At least three types of workstations are available to you: dumb terminals, thin clients, and personal computers. Which one you use depends on the needs of your company and your users. When you are planning for a new AS/400, you should

also inventory your available workstations so you can get an idea of how many can be used with the AS/400 and how many new workstations you will have to purchase. This point in your planning is also a great time to locate a supplier.

Dumb Terminals

Dumb terminals, or 5250 Display Stations, are those old, reliable green-screen terminals you’ve seen everywhere over the last twenty years. In fact, as far as functionality goes, they really haven’t changed much in twenty years, either. Oh sure, you can get them to display in color instead of in plain old green or amber, but, other than that, there’s not much new going on. The best thing about the dumb terminal is that it is both reliable and relatively easy to install, configure, and use. It seldom requires additional software to be loaded onto the terminal itself, which is a big plus when you have to support it on a daily basis. Generally, dumb terminals can be connected with any of the available wiring solutions. If you use anything other than twinax, you’ll probably need to purchase baluns to connect the twinax coming out of the terminal’s logic unit to the RJ45 connector on the end of your Cat5, twisted pair, or fiber optic cable. A balun is a small unit about the size of a D-cell battery that has two female connections: one that accepts twinaxial cable and the other that accepts a standard RJ45 (telephone jack) connector. Its purpose is to allow disparate cable connections to be made.

Thin Clients

Thin clients are relatively new and provide for a fully addressable display screen without the requirements of a large CPU, such as a PC has. Thin clients connect directly to the AS/400 and, like dumb terminals, do not require any additional software to be loaded on them. However, unlike the dumb terminal, the thin client must be configured to access your AS/400, and the AS/400 must be configured to recognize the thin client, usually using TCP/IP. The advantages of thin clients are that they are relatively easy to install, take up less space than a PC, and are able to display the same types of graphics you would expect from a PC. This can be advantageous if you use the thin client as both an AS/400 green- screen terminal and as a smart workstation that runs, say, Microsoft NT software from an Integrated PC Card (IPCS) inside the AS/400. Thin clients are also relatively inexpensive, and that fact once made them more attractive than PCs to budget-conscious data processing centers. However, now that the price of PCs has dropped so drastically, this is no longer the case. Thin clients can be connected to your AS/400 using the same methods as the dumb terminal.

Personal Computers

If you use a PC as an AS/400 workstation, you need to load some type of emulation software, such as IBM’s Client Access/400, Hummingbird’s HostExplorer, NetManage’s NS/Portfolio, or Wall Data’s RUMBA, on each PC that needs to connect to your AS/400. In addition, you may be required to load additional software on the AS/400 to allow the PCs to “talk” to the AS/400. The maintenance and support of PCs tend to be a lot higher than with thin clients or dumb terminals. This cost of support may be offset, however, by the benefits your users get by having a PC on their desk. If you have users who need to do a lot of spreadsheet or word processing applications, as well as occasionally get onto the AS/400, then a PC is the way to go. Another consideration is that the price of PCs has fallen so much in recent months that you can buy almost two complete PCs for the price of one thin client or one dumb terminal. You generally connect a PC to your AS/400 via twisted-pair, Cat5, or fiber optic cable. You can also connect it by using twinax if you install, inside of the PC, a 5250 Emulation board that has a twinaxial connector on it.

Much to Consider

As you can see, there are a lot of things to consider when planning for a new AS/400. You first need to think about how big the new AS/400 and its components are. (Its size, along with power and environmental issues, will determine where you install it.) You also need to consider the means of attaching your users to the AS/400, and, finally,

you need to determine what type of workstation they will use to access it. If you don’t already have it, order a copy of the IBM Physical Planning Reference manual before you order your new AS/400. A little bit of planning at the beginning will save you a lot of headaches at the end!


AS/400 Physical Planning Reference V4R3 (SA41-5109-02, CD-ROM QB3AWE02)

Panel Components Corporation, P.O. Box 115, Oskaloosa, IA 52577

Figure 1: This shows the dimensions for the Model 650 system unit in the 9251 Base I/O Tower and a companion 5057 Storage Expansion Unit.

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