MPG Helps to Size Boxes in a User-Based Pricing World
June 26, 2007 Alex Woodie
With the new user-based pricing scheme introduced this spring, sizing a new System i box has gotten a lot more complicated. For starters, while you may know exactly how many users need access to your i5/OS applications, how do you count how many concurrent user licenses you need? Also, how can you be sure the new entry-level 515, with its limitation on disks, can deliver the performance you need? A new release of Performance Navigator from Midrange Performance Group can answer these questions–and more!
Performance Navigator, or PerfNav, is a Windows-based capacity planning tool for System i servers. The software uses IBM‘s PM/400 data collection facility to gather performance data at regular intervals. As the base of System i performance data grows over the weeks, months, and years, a portrait of the user’s hardware needs starts to emerge, and PerfNav’s suite of tools can be used to accurately predict how growing workloads will perform against any combination of hardware from IBM.
Up to this point, the art of hardware sizing has been defined by several known factors, including batch and interactive CPW, disk and disk arms, and memory, among other factors. PerfNav could give an accurate prediction of what kind of performance users could expect if they added more or less of these resources to their next server.
However, since IBM launched the new System i models 515 and 525 “Express” servers earlier this year, there has been a new metric that comes into play: users and user-based licensing.
With these boxes–and only these boxes, for now–IBM is pricing and selling servers based primarily on the number of users that will use them. Sure, users can buy more disk or memory or activate the second core of the dual-core Power5 processor (on the 525, anyway–the second core on the entry-level 515 cannot be activated). But the main factor determining how much users will pay is the number of five-client (for the 515) or 10-client (for the 525) license packs that users must buy. The change should help IBM compete more effectively against Windows, but it’s thrown a curveball into the capacity planning ballgame.
For MPG, it meant going back to the lab to come up with a way to count users. And when IBM changed it user-based pricing policy earlier this month from total users to concurrent users, it meant that MPG had to find a way to count concurrent users, which isn’t as easy as it may seem.
“The problem is i5/OS users use the machine differently than Windows people use that machine, and it therefore makes it very different to count users and to count concurrent users,” says Randy Watson, president of MPG, which is based in Boulder, Colorado. “There’s a lot of detail here and that’s what took us a little while to get programmed.”
PerfNav needed some intelligence to be able to discern all of a user’s jobs from that user himself. For example, if 10 batch jobs are running under RWatson’s user profile, it would be erroneous to count each of those 10 jobs as separate users, Watson says. The product also had to be configured to exclude any of the default “Q” user profiles from its tabulations, because those aren’t true individual users.
“There was a lot of discussion–and still is–of what is a user,” Watson says. “The devil is in the detail.”
Some workloads pose special problems. For example, there is no way to accurately determine the number of concurrent users attached to a Lotus Domino implementation on the i5/OS server. “Domino is a big black hole,” Watson says. “It’s impossible currently to track concurrent Domino users.”
SAP poses similar problems. Because the ERP software giant implements its own operating environment on the operating systems it runs on, it is very difficult to use tools to count concurrent R/3 or mySAP users on the System i platform. Instead, organizations that run SAP on System i must use a tool provided by SAP to count concurrent users.
It’s also difficult if not impossible to track individual users logging onto the System i server externally through the Web server, but since IBM’s new pricing scheme mandates a separate license for external users (for $4,000), it’s not something that MPG has made a concern.
PerfNav can also play a valuable role with the new user-based pricing scheme by configuring DASD.
Configuring disk on the i525 is not such a big deal, because users can always add more disk–up to the 248 disk-limit anyway, but that should be enough for most shops. On the 515, however, IBM has imposed a limit of eight disks. This limit could pose problems for some shops hoping to get by on the cheapest System i server in recent history ($7,995), but whose workloads put them on the cusp of performance problems.
“The CPU is huge,” Watson says. “Most of these people in no way need 3,500 CPW. But the restriction now on the 515 is, because IBM has taken the gloves off with the cap [by moving to concurrent users from total users], can this machine support the workload with eight disk drives?” A graph in the new release of PerfNav can show prospective 515 customers when their disk drives will become a bottleneck in their system and lead to a CRITSIT, or a “critical situation” in IBM parlance, Watson says.
Not only can PerfNav keep organizations away from CRITSIT or from spending too much on licenses, but it can also help System i shops maintain their System i environments in a state of compliance.
While IBM is currently taking a “soft” approach to compliance–a warning screen alerting the administrator to excessive concurrent users is the extent of enforcement at the moment–that could change at any time. There are some reports that IBM has hired the accounting firm KPMG to audit its System i customers for compliance. IBM could also hard-wire the concurrent user limit into the boxes, making it even more important to get the concurrent user licensing thing right the first time around.
PerfNav 12.1 is available now. The product can be licensed for a single server for $3,695. Alternatively, users can get a 30-day license for $739. For more information, visit www.mpginc.com.