Remember the good old days when you could buy gasoline for a quarter a gallon? Back then, you never thought once about gas mileage, much less twice. It was almost amusing to watch the fuel gauge plummet to "Empty" as you cruised in the latest petroleum-guzzling wonder.
Those days are long gone, and not just for the automobile. At midrange computing sites worldwide, tightened budgets are forcing AS/400 managers to squeeze every drop of performance out of their systems. However, many managers are fighting a losing battle because they lack information about the least expensive ways to maximize AS/400 performance. As a result, they often waste money on CPU upgrades (and the higher software license fees they trigger) when a few inexpensive measures could solve their performance problems.
If you're considering a processor upgrade, this article will introduce you to techniques that could help you avoid such an upgrade and save thousands of dollars. In addition, we'll give you some tips on how to save money when you really do need more CPU horsepower.
Performance Tuning-The First Line of Defense
If your system's response time or batch performance is lagging, don't jump to the conclusion that it's the system's fault. Like your favorite set of wheels, your AS/400 needs periodic tune-ups. A good tune-up can often give you the same performance boost as a CPU upgrade at little or no cost. Here are the five most common problems according to Michael Catalani, a performance-tuning expert and president of Catalani Consulting in Memphis, Tennesee.
1. Low Utilization Levels - If you are not utilizing 100 percent of your processor, yet have batch work queued up, you are wasting system resources. While Catalani admits this runs counter to popular belief, he states, "Processor utilization has absolutely no bearing on response time. If your CPU utilization is 90 percent, it means the processor was idle 10 percent of the time. I run all my sites at 100 percent utilization, if possible, and get an average response time between 0.1 and 0.4 seconds."
2. Misappropriated CPU Power - Even when CPU utilization levels are high, the CPU cycles may be allocated inefficiently, resulting in poor response times. This problem arises when operators set improper priorities or time slices for jobs. According to Catalani, "Of all the performance problems you can correct, this one often provides the biggest instant payback."
3. Misuse of Logical Files - Logical files increase CPU and disk overhead every time their corresponding physical file gets updated. As a result, you should regularly evaluate all logical files to determine how frequently they are used.
Conversely, logical files can improve system performance, especially if you have jobs that take a long time to run selections and sorts.
4. Migrated Program Code - If you are using program code that originally ran on another system, it is possible that you're wasting overhead. You may recover system resources by reengineering the migrated code. Start with those programs that utilize the most CPU cycles. You can identify these programs by running the AS/400's performance monitor with trace data and printing the transaction report.
5. Improper Security Settings - While it is important to protect your AS/400 from unwelcome guests, security levels 30 and above can eat up CPU cycles if you do not implement them properly.
Once you have addressed these five major problems, you should turn your attention to how your AS/400 manages memory since this has a profound impact on response times. This does not mean, however, that you should buy additional memory for your system the minute response times fall below acceptable levels.
Believe it or not, most AS/400s (except the older B-series) have enough memory to effectively manage most work loads. However, many AS/400 sites do not know how to tune their memory for maximum efficiency. Memory-tuning recommendations are beyond the scope of this article; but before you upgrade your system, you should examine the alternatives offered by performance tuning.
Once you've tuned your memory, you should consider DASD performance. Again, before you assume that more or faster disk drives are the solution, you should attempt to fine-tune the hardware you have. You need to consider three major factors when evaluating DASD performance: fragmentation, queueing time and service time.
As the phrase suggests, fragmentation takes place when the AS/400 spreads, or fragments, individual objects across several drives. As a result, the system must make several disk accesses to get the data that it could otherwise obtain with just one access. Fragmentation occurs naturally on every AS/400 and lowers performance levels. You can periodically defragment your DASD, but consult with a systems engineer or performance-tuning expert before doing so.
Excessive disk queueing and disk service times can also rob your system of required horsepower. Queueing time is the amount of time that a request for disk access must wait for service by the disk containing the needed data. As this definition implies, disk access requests must sometimes wait in line for heavily used drives. Service time is the amount of time it takes a given drive to process a request once it is first in line.
Service times are largely a function of disk drive and controller performance, so you can usually improve them by replacing slower drives and controllers with faster ones. Improving queueing times, however, is a more complex process that involves a variety of methods-consult the literature on system and performance tuning for more information.
As all of these suggestions indicate, there's a lot you can do on your own to tune your system. If you do not have the time or expertise to perform your own tune-ups, you can benefit from the services of an expert AS/400 mechanic. According to Catalani, the typical tune-up costs between $3,000 and $5,000. Compared to the price of a system upgrade, such an expense is minor.
Memory and Disk Upgrades
Suppose you've tuned your system until it's purring like a cat but you still need more power. The next step is to consider upgrading your memory or DASD. While this alternative is more expensive than performance tuning, it's far less costly than a CPU upgrade.
To find out if a memory or disk upgrade will solve your problem, you should check a few key indicators. First, look at the fault rates for each of your memory pools after you have tuned your CPU and memory. If the sum of the fault rates for all pools exceeds 20 per second, there's a strong possibility that your memory is constraining your system's performance. If so, adding memory could solve the problem. Right now, IBM memory sells for a list price of $765 per megabyte (MB), but its street price is lower. You can also acquire used or third-party memory at a fraction of the price of new memory.
When it comes to DASD, the key factors are the busy levels for each of your disk arms (the devices that move the read/write heads across the surfaces of your disks). When any one of the disk arms is busy more than 40 percent of the time, your performance suffers. You can often remedy this situation by reallocating the data accessed by this single arm across your drives; this solution works best when some of the disk arms are running at less than 20 percent busy.
If most of the disk arms are running at 25-35 percent busy levels after you have rearranged and defragmented your data, you have a hardware problem on your hands. According to Catalani, "[Such a situation] indicates that the drives are being overworked, the I/O processors are probably overworked and performance is taking a severe hit."
To alleviate this situation, you need to add more disk arms or replace some of the currently installed arms with faster ones. If you have any 9332s or 9335s on your system, consider replacing them with IBM's newer 9336s and 9337s or plug-compatible equivalents from third-party manufacturers. These models have faster disk service times, which will reduce the busy levels on their disk arms. They also have much higher capacities than 9332s or 9335s; by increasing your total disk capacity, you can put less data under every disk arm, reducing busy levels.
Divide and Conquer-The Art of Splitting Systems
If you've done everything I've discussed and still have a performance bottleneck, you should probably accept the fact that you're running your system at full throttle. However, you shouldn't necessarily upgrade your current engine to a bigger one yet. You could save quite a bit of money by purchasing a second small system and splitting your work load across the two systems instead of upgrading your single system.
As a rule of thumb, an AS/400 is a good candidate for splitting if it meets two criteria. First, it must be running two or more discrete work loads that have minimal interaction with each other and frequently use separate applications. Second, all of your upgrade alternatives must force you to move from one software price group to a higher one. When this is the case, you have to pay for the upgrades to your software licenses as well as for the hardware upgrade. These fees are what make CPU upgrades so expensive, and are the chief economic incentive for system splitting. A split lets you transfer some of your current licenses to the second system at little or no charge instead of upgrading those licenses to a larger system.
Overburdened systems that run both development and production tasks are frequent candidates for splitting, and for more than financial reasons. According to Bob Kleckner, vice president of Technical Marketing for XL/Datacomp, "Splitting off development on its own system is a good idea for three reasons. First, programmers know how to take over a system. Second, the development life cycle puts sporadic strains on a system that can slow response times during peak hours. Finally, it makes it easier to justify a future production system upgrade when your capacity needs are being fueled by business growth instead of the short-term performance bottlenecks your developers create."
How large a system will your developers need if you give them their own AS/400? The capacity needed by programming staffs varies widely from company to company. However, Kleckner uses the percentages shown in 1 as a general guide to the capacity needed per programmer. Say, for instance, that you currently have a single AS/400 model F35 and a staff of three programmers. According to IBM, your system has a performance rating of 4.8, which means it can run 4.8 times faster than an AS/400 model B10. On average, each programmer working on a model F35 uses around 4 percent of its total capacity. Thererfore, three programmers consume around 12 percent of the system, an amount which is less than the capacity of the smallest AS/400.
How large a system will your developers need if you give them their own AS/400? The capacity needed by programming staffs varies widely from company to company. However, Kleckner uses the percentages shown in Figure 1 as a general guide to the capacity needed per programmer. Say, for instance, that you currently have a single AS/400 model F35 and a staff of three programmers. According to IBM, your system has a performance rating of 4.8, which means it can run 4.8 times faster than an AS/400 model B10. On average, each programmer working on a model F35 uses around 4 percent of its total capacity. Thererfore, three programmers consume around 12 percent of the system, an amount which is less than the capacity of the smallest AS/400.
Let's take the example of the AS/400 F35 and compare the cost of splitting it against the cost of upgrading. Suppose you are running this system at peak performance with three programmers and the following software licenses: OS/400, PC Support/400, RPG/400, Application Development Tools, SQL/400, OfficeVision/400 and Query/400.
Only the programmers utilize RPG/400, the Application Development Tools and SQL/400. Both the programmers and the users need PC Support/400 and OfficeVision/400. In addition, this system runs a variety of production applications. If you use packaged software with tiered pricing for any of your applications, the cost of upgrading the system would be much higher than the following comparison indicates.
You have two alternatives to get the capacity you need. You can upgrade to an F45 and pay the increased software license fees that go with the upgrade, or you can purchase a small system for your programmers and transfer the licenses for their development tools to the small system. Upgrading the F35 to an F45 will cost $34,000 for the hardware alone. In addition, the cost of upgrading the software licenses will run you approximately $45,000, for a total cost of around $79,000.
By comparison, the cost to split this system is minimal. You can easi-ly put three programmers on an F02. This removes about 12 percent of the total work load from the F35 and lets you defer the upgrade. The base model F02 has 8MB of memory, a gigabyte of disk storage, a workstation adapter and a quarter-inch cartridge tape drive. After purchasing this system, you could transfer the licenses you hold for RPG/400, the Application Development Tools, and SQL/400 from the F35 to the F02 at no charge. The cost of this package, along with an additional gigabyte of disk storage and licenses for OS/400, PC Support and OfficeVision/400, is around $20,000, or about 25 percent of the cost of upgrading the F35.
Naturally, not all system splits yield such dramatic savings. Some, however, actually save you more. This is especially true if you face a forced migration from a 9402 to a 9404 system or from a 9404 to a 9406. In such cases, system splitting lets you avoid an extremely expensive move to a different footprint.
So...You Still Need to Upgrade?
You've tuned your system to peak performance, added memory and disk capacity and split your systems in every way that makes economic sense. What's left? Unfortunately, it's time for you to bite the bullet and upgrade the CPU on at least one of your systems.
However, there's more than one way to upgrade a system, and not all options are equal from the perspective of the bottom line. If you take the following six rules to heart, there's a strong chance you'll spend much less than you originally expected to get that bigger engine.
If you have an AS/400 model D or E, upgrade your system to a higher letter and the same model number whenever possible. For instance, instead of upgrading an E35 to an E45, upgrade it to an F35. The reason behind this rule is simple: increased software fees. Every time you upgrade to a higher model number, you place yourself in a higher IBM software pricing group and trigger license upgrade fees. Most software vendors, including IBM, will charge you nothing if you stay within the same model number as you upgrade to a higher letter within the D/E/F series. However, if your situation requires you to move from a B- or C-model to the D/E/F group, the strategy described in Rule 4 better suits your purposes.
If you have an AS/400 model D or E and must upgrade to a higher model number to get adequate performance, try to minimize software license upgrade fees. Some software vendors offer a user-based license option which could save you money.
Traditionally, most AS/400 software vendors have priced their products on a tiered basis in which license fees rise along with model numbers. Under this system, customers upgrading their processor to a higher number usually pay a fee to upgrade their software. Over the last year, however, IBM and other vendors have begun offering a second option: pricing based on the number of users. Thus, if you hold a processor-based license and face an upgrade fee when you move to a higher model number, you may be able to avoid that fee by switching to a user-based license.
Imagine, for instance, that you must upgrade an AS/400 F35 to an F45 and have a processor-based license for OfficeVision/400. To upgrade your processor-based license to the F45 level, you must pay IBM the difference between the cost of an F45 license and an F35 license, or more than $9,000. However, if you convert your processor-based license to a user-based one, the tab for the conversion could be as low as $1,000 (your actual cost will vary based on the number of OfficeVision users on the system). Because the rules regarding such conversions are often complex, talk to your software vendors to determine your options.
There is another tactic you should use to slash hardware costs when upgrading a D or E system to a higher model number. This tactic is commonly called "downgrading to upgrade" among used equipment dealers. Customers who use this tactic do not actually upgrade their current system; instead, they trade it in for a smaller or older model that the dealer upgrades to the necessary performance level. For example, suppose that you currently own an AS/400 E35 and, as a result of a merger, need a drastic increase in performance to a model F50. Your model E35 has the following options:
o 40MB of memory o Tape attachment (feature #2621) o Six-line communications controller (feature #2623) o Two-line communications adapter (feature #2654) o Twinaxial device controller (feature #6050) o Magnetic storage device controller (feature #6112)
Your destination system (the model F50) will have the same features but will have 96MB of memory, a system unit expansion (feature #5042) and two additional communications adapters (feature #2654). There are three ways to move from an E35 to an F50: upgrade your E35 to an F50; trade in your E35 for an F50; or trade in your E35 for an older B-series model that the dealer upgrades to an F50. While the first two options currently cost around $160,000 each to execute, the third option costs only $115,000 for a savings of 28 percent.
If you have a B- or C-series system and must upgrade, move to an F-series system using the downgrade to upgrade strategy whenever possible. Such a strategy maximizes your chance of avoiding software license upgrade fees. Imagine, for instance, that you own a 9406 B50 and need a system with 50 percent more performance. At present, IBM will upgrade this system to a model E50, F50, or higher-numbered model in the E-series or F-series. All of these upgrades force you to increase your performance by at least 100 percent. In addition, every option involves software license upgrade fees.
To avoid these fees and get the upgrade you want, you could trade in your B50 for a B35 that your dealer upgrades to an F35. This system has 50 percent more performance than the B50 and is in a lower-priced software group. As a result, you will pay no license upgrade fees.
Whether you upgrade your present system or trade it in as part of a downgrade- to-upgrade strategy, migrate as many of your old system's feature codes to the new system as you possibly can. Feature codes, like the options on your car, cost a bundle. Just imagine the money you would save if you could transfer your old car's air conditioner or sunroof to your next car, and you'll understand why you should take advantage of the opportunity to migrate feature codes on your AS/400.
Above all, invite competitive bids for your planned upgrade from a large number of qualified dealers. Look at all the bids and select the most interesting ones for further review. Then, negotiate concessions from the two or three dealers with the most attractive offers. If you don't have negotiation experience, read up on the subject or consider hiring a consultant who is an expert in the field. The savings you can realize are considerable.
A Closing Reminder
In conclusion, you should follow an orderly series of steps whenever your performance needs outpace your AS/400's capacity. First, tune all of your system's components, including memory and disk. Second, consider adding more memory or disk capacity if your measurements indicate that either component is constraining the system. Many midrange professionals who take these steps will discover their system has all the horsepower they need.
The day will come, however, when your CPU can no longer carry your work load. When that happens, see if you can save money by splitting that load across two systems before upgrading your single system. Then, if you have no other choice, use the rules covered in this article to make that upgrade as inexpensive as possible. By taking these steps in order, you'll have the pleasure of cruising past other companies that are paying top dollar for their AS/400 upgrades.
Lee Kroon is an industry analyst for Midrange Computing.
Intelligent Upgrade Alternatives
Figure 1 Computer Capacity Consumed by the Average Programm
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