Hi, John. No such thing as a stupid question, imho....stupid answers, maybe....;-) McKown, John wrote:
Yes, I know this will be a stupid question. But I will ask anyway because I have no fear (or was that no sense?). A zAAP engine is used by z/OS to run Java code. The only reason for such an engine was because of the CPU demands of Java and the fact that adding the required CPU power using a general purpose engine would drive up the other software costs. That is, a zAAP engine is a marketing ploy to "sell" Java (an maybe some other Java-dependant software such as WAS). It is not a solution to a technical problem with Java on z/OS. Therefore, there is no need/reason for Linux on System z to ever support a zAAP (or zIIP or other specialty engine which is "marketing" oriented). True?
True. All of the "specialty" engines now available are meant as a way to add horsepower to a zSeries box without increasing the software costs, from both IBM and 3rd party ISVs, associated with the "normal" workload being run on the standard engines...... While it might be nice if Linux, running on an IFL, could dispatch a Java process on a zAAP, it is not a requirement. I would think the performance gain might be worthwhile, especially if the Linux guest was running Websphere.
OK, why the stupid question? I am hoping (perhaps in vain) that eventually we may get a zAAP to do Java work on z/OS and to get back my IFL (lost during our z9BC upgrade due to "lack of interest") for possible Linux on System z work. Our current management incarnation is very open towards Linux. But they still act like Linux only runs on Intel. Well, it beats the previous "Windows is the solution to every problem!" attitude of the previous management group. Anyway, I am fairly sure that somebody in management is going to ask something like: "Why can't I run z/OS Java on an IFL?" or "Why can't I run z/Linux on a zAAP?". I.e. they'll want to get a single speciality CP to do both z/Linux and z/OS Java. This in order to reduce hardware costs. I know they are not expensive, compared to a general CP, but we are very cost conscious, as is reasonable.
Go talk to IBM, they might be able to give you some options that we are not aware of yet. IBM has designed these specialty engines in such a manner that they can *not* run general purpose workloads, e.g., the IFL is missing an instruction that z/OS requires in order to IPL, so 3rd party ISVs can be assured that their applications will not run there. The zAAP processor may be designed such that it supports only those instructions that are used by the Java vm, and may not be capable of running zLinux at all. Hope this helps.
-- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology
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