Introduction
This chapter provides a brief and somewhat generalized high-level overview of Independent Software Vendor (ISV) IBM Z Program Development Tool (IBM zPDT). This chapter is intended for potential or new ISV zPDT customers. Experienced ISV zPDT users may skip this chapter.
zPDT is part of several licensed IBM products that use a personal computer (PC) running under Linux to emulate an IBM zSystems mainframe that is used for software development and testing purposes. The emulated mainframe environment uses a licensed IBM zSystems operating system, such as z/OS, IBM z/VM®, or an Linux on IBM zSystems system.1 The IBM zSystems operating system (with more software) is used to develop and test whatever applications are relevant.
Over the years, the name of the IBM mainframe family has changed several times. Some recent names have been IBM System z®, IBM z System, IBM Z, and others. The current name is IBM zSystems, and this name is used in this publication.
1.1 Frequently asked questions
This section describes some of the frequently asked questions about ISV zPDT.
What is the full name of the zPDT package
At the time of writing, there are two basic zPDT product packages that are intended for development and testing:
1. ISV zPDT, which was formerly known as zPDT. The full name is Independent Software Vendor IBM Z Program Development Tool, although this expanded name is rarely used; within this publication, we use ISV zPDT as the short name.2 This product is intended for a particular set of independent software development companies,3 and it is also widely used within IBM.
2. IBM ZD&T, which was earlier known as RDzUT and RD&T and zD&T. The full name is
IBM Z Development and Test Environment; within this publication, we use IBM ZD&T as the short name. This product is intended for normal IBM zSystems customers, and it involves many licensing and pricing agreements that are established when the product is acquired by a customer.
Much older documentation used the zPDT name as a generalization or because it was written before IBM ZD&T was created. Such documentation usually applies to what is known as
ISV zPDT, and it might not include changes that are relevant to the IBM ZD&T product. More recent documentation (including this IBM Redbooks publication) tends to use either the
ISV zPDT or IBM ZD&T names.
Both products use the core zPDT program4 as the base element, and the current naming conventions are a bit confusing because this core zPDT program is part of both ISV zPDT and IBM ZD&T. This publication sometimes uses the simple name zPDT when referring to core (or base) characteristics of the main program.
 
Tip: This publication is primarily about ISV zPDT. While many of the technical details in the publication also apply to IBM ZD&T, you must consult IBM ZD&T representatives or documentation to understand usage differences or extensions that apply to IBM ZD&T.
Some aspects of zPDT technology are present in other IBM offerings, which are not covered in this publication.
What is the purpose of zPDT
ISV zPDT is licensed for software development and some basic software testing. It is not licensed or appropriate as a production system. Defining a software development group within a large organization where there is overlap between “development” and “production” can be confusing, which is a topic for discussion with an IBM representative or a recognized zPDT vendor.
The key point is that ISV zPDT is not valid for application “production” or performance measurement usage. Such usage would violate the licensing agreements for the zPDT product, the IBM zSystems operating system, and other IBM licensed products, and probably other licensed software that is used on IBM zSystems.
Usage of IBM ZD&T can be in a wider scope depending on sales and contractual details. An appropriate IBM ZD&T representative should be consulted for details.
Does either zPDT version include an IBM zSystems operating system
This question involves distinguishing between the core zPDT material and what is available in a product package from IBM:
•ISV zPDT itself does not include any IBM zSystems software or operating systems. However, the license to use ISV zPDT usually contains access to a specially generated z/OS operating system that contains many IBM z/OS software products. The associated z/OS (or z/VM) sets are commonly known as Application Development Controlled Distribution (ADCD) z/OS or ADCD z/VM.
•The IBM ZD&T product is typically licensed to include access to a special z/OS system and (in some cases) to a special z/VM system. Other license aspects are possible.
Viewed a different way, the core zPDT development group within IBM is not directly involved with helping customers with complex IBM software products such as z/OS, large z/OS applications, and others. This basic status applies to ISV zPDT users. The IBM ZD&T product can provide more support in such areas.
Does this IBM Redbooks publication cover both ISV zPDT and IBM ZD&T
In general, the answer is no. This publication applies primarily to ISV zPDT, with only a few references to IBM ZD&T, although this chapter contains some comments about IBM ZD&T and general zPDT information. The remainder of the publication (except for Appendix D, “IBM Z Development and Test Environment notes” on page 387) usually does not mention
IBM ZD&T, and normally contains references to ISV zPDT.
Are ISV zPDT and IBM ZD&T priced the same way
No. The licensing and pricing details are quite different and must be discussed with an
IBM representative or zPDT vendor.
Can I run either ISV zPDT or IBM ZD&T after I obtain zPDT
ISV zPDT and IBM ZD&T are separate products and require different license tokens. An
IBM 1090 token that is used for ISV zPDT does not work with IBM ZD&T, and an IBM 1091 token that is used for IBM ZD&T does not work with ISV zPDT. It is not practical to try to alternate between ISV zPDT and IBM ZD&T. Select whichever one is most practical for you and stay with that one.
How are the two zPDT products derived
Figure 1-1 provides a generalized overview.
Figure 1-1 zPDT overview
The core zPDT modules (1 in Figure 1-1) are standard, and many are referenced throughout this publication. These modules form the basis (2) for both ISV zPDT and IBM ZD&T. For
ISV zPDT, it is possible for special vendors (such as Information Technology Company (ITC)) to add operational enhancements that do not interfere with normal ISV zPDT usage (3).
IBM ZD&T adds substantial changes and enhancements that can change the basic usage of zPDT (4). The ADCD operating system package is built by a different group in an IBM organization (5). The z/OS version that is potentially delivered to IBM ZD&T customers contains modifications that are not present in the ADCD package that is provided for
ISV zPDT users, and might not be associated with the ADCD terminology. IBM ZD&T users (6) might each have different components or different license agreements.
What are the components of the core zPDT modules
In addition to the IBM zSystems emulation module, the core zPDT material contains several Linux commands for zPDT administration and several IBM zSystems I/O device emulation modules. The basic zPDT “component” consists of many lower-level executable or control-level Linux files. At this lower level, an ISV zPDT installation results in three Linux directories:
1. /usr/z1090/bin contains about 200 Linux files, which mostly are executable files that are related to ISV zPDT run time.
2. /usr/z1090/man/man1 contains about 100 brief documentation files for various ISV zPDT commands and operations.
3. /usr/z1090/uim, which might not exist until ISV zPDT is started, contains a few, small license-related files.
In addition, there are small files (mostly log files) in a home subdirectory of the Linux user ID that are used to run zPDT.
What are the zPDT tokens that are needed
These tokens usually are physical USB devices that appear the same as small USB flash drives. Although there are exceptions, the tokens usually contain a 1-year license for a number of emulated IBM zSystems processors.5 The licenses are typically renewed by an online process to update the token. (A more advanced system for IBM ZD&T can involve “software only” licenses.) The tokens have IBM part numbers 1090 (for ISV zPDT) or 1091 (for
IBM ZD&T). The tokens are provided through the same vendor (IBM or a third party) that markets either zPDT product. The USB token (or “software license”) must be accessed by the PC running zPDT in order for zPDT to function.
The tokens that are used at the time of writing are so-called “Generation 1” tokens. At some point, there might be a move to “Generation 2” tokens. For practical purposes, Generation 2 tokens are approximately the same as the older version, and the customer usage is about the same. The newer tokens have different program interfaces, but they are internal to the zPDT programs.
You talk about PC Linux, but can I run zPDT under Microsoft Windows instead
zPDT is a complex application that is written to run on a PC Linux base machine. There is no version that is written for Microsoft Windows. All the discussions (in this publication or in various internet forums) assume an understanding of the base Linux requirement.6
Is zPDT useful for such things as IBM Parallel Sysplex and multithreading
Yes, but with practical limitations based on PC performance, memory sizes that are available, and others. IBM ZD&T requires a modified license for IBM Parallel Sysplex® emulation.7
ISV zPDT licenses require no modifications. Parallel Sysplex operation, at the time of writing, is limited to multiple z/OS guest images within a single z/VM image on a single zPDT base system. For more information, see zPDT Sysplex Extensions - 2020, SG24-8386.
In general, the same “multithreading” techniques and applications that run on an
IBM zSystems mainframe can be used under zPDT. Practical differences, such as memory sizes and emulation performance, might be relevant.
What kind of PC is required
The PC can range from a small laptop to the largest PC server that is available. A small
ISV zPDT plus a z/OS system, probably with a single z/OS user, might be used with a laptop containing 8 GB of memory and two cores and having at least 250 GB of available disk space, but this setup would have limitations.8 A typical small ISV zPDT plus a z/OS system might be based on a PC with at least 16 GB of memory, about 500 GB of available disk space, and four PC cores. This setup can service multiple z/OS users if no large databases or applications are involved.
A larger ISV zPDT system might have much more than 32 or 64 GB of memory, terabytes of disks, and at least 10 PC core processors. One basic requirement is that the PC must have at least as many processor cores as there are defined IBM zSystems processors (CPUs) for
ISV zPDT.
The actual required size depends on the number of simultaneous users, the IBM zSystems applications that are involved, the size of IBM zSystems databases that are involved, and others. There is no simple formula for deriving the exact PC size that is required, or even if the intended project is practical on a zPDT PC. If you want a large or complex operation, contact an appropriate IBM representative, or an ITC presentation might be appropriate.
Although a basic PC system can be simple to configure and acquire, the more advanced PC servers can be a bit more complex. If your plans require an advanced machine, contact a knowledgeable IBM or ITC advisor.
Who is ITC
Information Technology Company is an IBM associated vendor who supplies most of the
ISV zPDT systems that are now in use and some of the IBM ZD&T systems. They offer several options for extra support levels and depending on your skill levels, these options might be important. ITC also offers PC hardware systems that are especially suited for zPDT.
The primary ITC office is at 7389 Lee Highway, Falls Church, VA 22042 (telephone 800-994-9441). They have more offices in Germany and Great Britain. A general method of contacting ITC is by emailing them at [email protected].
Can I move to a new, faster PC with ISV zPDT
Yes, although your ISV zPDT vendor might want updated information about which PC you are using. The ISV zPDT token itself is not sensitive to a particular PC. However, after you have a general high-end PC, then advancing to a new machine is unlikely to yield much improvement in basic zPDT performance. Areas that often help performance are more PC memory and the replacement of “real” PC disks with solid-state drives (SSDs).
Is zPDT as fast as an IBM zSystems machine, and how fast is it
The simple answer is no. Furthermore, there is no linear relationship between zPDT performance and an IBM zSystems machine. Some emulated functions (such as a reasonable sequence of common IBM zSystems system instructions) can be acceptable, and others can be much slower. Although IBM does not provide any detailed zPDT performance specifications, some customers describe performance that is about .06% the speed of a “real” IBM zSystems CPU processor, but with many more comments about various positive and negative exceptions. Such comments and declarations involve considerable background information about the hardware that is involved, the nature of the applications, and other concurrent operations. Again, specific information about performance is not provided by IBM.
Some common tasks, such as COBOL compilations, seem to perform well, while others, such as Java usage, tend to be on the slower side. Again, if you have specific goals that are a bit unusual, contact your zPDT source.
It should be understood that the primary goal of zPDT is the accurate emulation of
IBM zSystems system instructions, which is an important factor for software developers and takes precedence over performance factors.
How reliable is the ISV zPDT or ZD&T product
This answer can be more complex than expected. We have some ISV zPDT customers who experience months of continuously running their system, but a few complain about weekly problems. Investigations of various situations almost always detect a larger-than-expected variety of system involvements, such as extra Linux root-level monitors (especially internet monitors), unreasonable system expectations, poor (or uninformed) memory planning, odd applications, more (and often poorly defined) Linux loads, and others.
Another factor is the basic reliability of PC hardware, including disk drives, local area network (LAN) connections, LAN administration, power supplies, routers, and others. (This statement is not intended to degrade PC hardware or environments, but it is something that must be considered.)
Are all IBM zSystems functions emulated
No.
Can any application be developed or tested with ISV zPDT
The typical answer is most but not all. For example, there can be practical limitations on memory usage (consider an application that randomly and extensively addresses 900 GB of data in memory, running under zPDT on a laptop with 16 GB of memory) and limitations on some special styles of applications (consider an application that wants to do low-level manipulations of an IBM zSystems system cryptographic adapter). If you (as a potential
ISV zPDT customer) are considering zPDT usage for a really “odd” or “huge” project, then you might want a specific and detailed conversation with your IBM representative or zPDT vendor.
zPDT systems typically run IBM software such as operating systems, compilers, and others, but this software usually is not seen as “applications.” Applications are typically customer-written programs for whatever data processing development that the customer needs,9 and zPDT can provide a working tool for developing and testing many such applications. The ADCD z/OS system that is often associated with ISV zPDT has
IBM CICS®, IBM Db2®, IBM Information Management System (IMS), IBM WebSphere® Application Server, and IBM z/OSMF preconfigured for basic use, and they can be “starting points” for some application development work.
We have some old PC tape drives: Can they be used by z/OS
The answer is possibly. During the years of typical PC availability, there has been a wide range of “real” tape drive options, some involving detailed selections of cables types, cable speeds, PC adapters, and adapter options. The current ISV zPDT versions are sometimes briefly tested with a limited set of these options, and the ISV zPDT developers are aware that there are relatively few ISV zPDT tape drive users. Contact ITC about tape drive questions. Specific information about the relevant tape drives (and adapters and cables and control options) is needed.
Also, ISV zPDT can be configured with emulated tape drive operation, where the emulated tape is just a Linux disk file. This usage is much more widely used than “real” tape drives.
My z/OS skills are limited: Does ISV zPDT provide simple assists for z/OS
No. ISV zPDT emulates an IBM zSystems hardware machine. If you run z/OS on an
ISV zPDT system, then you (or someone helping you) need some basic z/OS skills. Roughly the same degree of skills are needed whether running z/OS on zPDT or on a “real”
IBM zSystems machine.10 The z/OS ADCD system that is typically associated with an
ISV zPDT license is a “real” z/OS system in that it was configured and tested on a “real”
IBM zSystems machine. z/OS (or any other IBM zSystems operating system) is not part of the core zPDT program.
Is ISV zPDT or IBM ZD&T suitable for basic z/OS learning
The “underlying” z/OS version is the key point. With ISV zPDT (and “standard” IBM ZD&T), the underlying z/OS is assumed to be a fairly complex z/OS environment. The typical customers often have many years of IBM zSystems and z/OS or z/VM experience,11 and the ADCD z/OS systems that are provided with the ISV zPDT product contain many complex options and setups. Also, the documentation that is involved (such as this publication) is not written as basic IBM zSystems learning material.
zPDT that is combined with a more basic and simplified z/OS system can be used for practical IBM zSystems learning, although this learning benefits from different options for the z/OS configuration, a different set of practical educational documentation, access to relevant help for the student, and a specialized license agreement. The zPDT program itself is the same in all cases.
Does IBM provide an IBM zSystems Linux package for ISV zPDT
No. You must find and download a distribution of Linux that is built for use on IBM zSystems machines. Many of our ISV zPDT customers have done this task, and several versions or levels of Linux for IBM zSystems machines exist. These distributions of Linux are not IBM products, and the ISV zPDT development team does not attempt to test every one of these distributions. Over the years, some problems were detected, mostly related to attempts to install Linux for IBM zSystems from DVD if the new image contains some obscure change to the DVD format or the installation details.
New IBM zSystems Linux versions sometimes contain low-level alterations that do not routinely work with the zPDT emulation available then, and they might depend on clever bypasses or future zPDT releases.
Obtaining more IBM software for ISV zPDT
“I want to order ISV zPDT and the z/OS ADCD system. Then, I want to order more IBM software that is not already included in the z/OS ADCD system. How do I do this task? How do I acquire IBM software fixes?”
In a simple environment, none of these items are routinely available. ISV zPDT and the ADCD systems do not provide a general license for more IBM software or software maintenance. The ADCD systems that are used with ISV zPDT are special cases of unique IBM license handling. In the most general case, ordering more IBM software requires more licenses for that software, and the licenses that are involved probably are more expensive and less relevant for ISV zPDT usage.
It is important to understand the IBM license limitations for ISV zPDT and ADCD systems. These offerings bypass the normal license fees that are associated with IBM zSystems machines and related IBM software. However, this “bypass” also bypasses access to normal IBM Support, maintenance (such as software fixes), and the ability to request IBM software changes. New ADCD releases for z/OS are generally offered every 6 months, with some variations in the timing. Assuming that your ISV zPDT license agreement includes access to ADCD systems, this agreement is the primary “IBM software maintenance” that is offered for ISV zPDT customers. However, the ADCD implementation group does offer a method of downloading IBM maintenance service (program temporary fixes (PTFs)) and some APAR information) in the form of monthly available downloadable large files. Substantial z/OS experience (and considerable time) is needed to handle this approach, and few ISV zPDT users attempt it.
I want to use my company’s installed z/OS instead of the ADCD version
In principle, the normal ISV zPDT license includes access to the current ADCD z/OS version and no other version of z/OS. You should discuss this topic with your IBM representatives for a possible variation to the normal ISV zPDT or IBM ZD&T license terms. An important consideration is the practical needs of your “company” z/OS. Do you expect cryptographic adapter adjustments, or Parallel Access Volumes (PAVs), or HiperSockets, or any of the more complex disk control unit functions? A reasonably skilled z/OS administrator12 can manage such issues for ISV zPDT, but you must have such an administrator available.
I want z/VSE software development: Is there another zPDT publication for me
No. This publication mostly describes ISV zPDT usage for a z/OS environment. ISV zPDT often is in a z/VSE environment, although there is no formal IBM testing involved. Many of the ISV zPDT details in this publication should also apply to z/VSE environments.
How can I protect my zPDT license token
An ISV zPDT token is required in a PC USB port to use ISV zPDT. (A special exception exists for IBM ZD&T “software licenses.”) The token can easily be unplugged and removed, although this action stops any ISV zPDT operation. One security option for some high-end PC servers is a hardware design for installing USB “sticks” internally in the PC. Another potential security option is to install the zPDT token on a remote zPDT license server where this remote server is in a more secure location. (ITC offers a special small remote device for this approach.)
Which PC Linux should I use for my base
Several Linux distributions are mentioned in this publication. However, we stress that the latest Linux releases, or the latest updates or fixes, are sometimes not the best choices.
ISV zPDT is a rather complex Linux application, and the latest Linux changes sometimes create hidden issues.13 ISV zPDT usage is typically a major undertaking, and the PC Linux that is involved is generally dedicated to this purpose. A stable, reliable Linux base, showing good ISV zPDT operation, is often regarded as better than the latest Linux alterations.
 
Tip: ISV zPDT installation is usually easier if you use one of the Linux distributions and levels that are listed in this publication. (See 2.5.1, “Current release” on page 44 for details.) These bases are the ones that were used for testing the current ISV zPDT release. Attempting to use different Linux distributions or levels might lead various minor issues.
What about new Linux releases and fixes: Are they good for zPDT
Maybe. zPDT installation is mostly handled by an installation program that is part of the zPDT package. Linux releases and updates often have minor internal changes that are relevant to zPDT and sometimes cause the zPDT installation process to encounter problems. There are usually fixes or bypasses that are needed to overcome such problems, but using them creates a delay that might be inconvenient. New ISV zPDT releases are typically based on the Linux levels current at the time that the release development started. One solution to this question might be to stick with the listed Linux levels, when possible, and update them when installing a new ISV zPDT release.
Some Linux updates (assuming you decide to apply them) require a Linux restart and perhaps some minimal testing. Depending on your usage of zPDT operation, this approach might require more planning on your part.
How do I access z/OS or z/VM on my ISV zPDT machine
You can install ISV zPDT and the appropriate IBM zSystems operating system on one PC (with a base Linux) and use 3270 emulators on the same PC (running under the base Linux) or on other machines (whether they are Linux systems). The 3270 emulator can be x3270, or almost any other modern 3270 emulator product. Accessing your zPDT setup from other PCs requires network connections, and there can be many variations of this operation.
How much PC Linux skill do I need to use ISV zPDT
You need basic Linux skills to install and administer ISV zPDT, but no in-depth Linux development work is involved. ISV zPDT, in general, does not depend on specific Linux desktop options or the existence of a Linux GUI, but it might (depending on your usage plans) need Linux firewall management and communications setups. These items are largely Linux options, not ISV zPDT options, and they might be important to your Linux or ISV zPDT users. Someone in your organization might need a skill or outside assistance to produce a Linux installation that is acceptable for your users.
An important area is LAN usage. zPDT LAN usage (through IBM zSystems Open Systems Adapter (OSA) emulation) works well with basic LAN interfacing. Dealing with VPNs, firewalls, DHCP, multiple OSA adapters (especially when connected to the same LAN network), complex or changing virtual or container usage, router changes, and others can require more networking skills.
We have seen a few cases where the Linux owner has “adjusted”, “customized”, “built from scratch”, or “experimented with details that they did not understand” and encountered
ISV zPDT problems. A clean installation of one of the Linux distribution levels that are listed in Table 2-3 on page 45 should not encounter unusual problems.
Also, recent Linux distributions that are used for zPDT are tending to be distributed as “large” ISO files that do not fit on a DVD, even though they might have “DVD” in their release title. In practice, this approach usually means that the distribution must be downloaded to a USB flash drive that, in basic usage, contains nothing but the ISO files.
Can I use a virtual or container base
Some ISV zPDT customers use virtual or container bases, which are acceptable, although intelligent planning is needed. For example, these environments often over-commit PC resources, or create “containers” that are much too small for reasonable zPDT performance, need more complex communications arrangements, or present reduced zPDT administrative interfaces. As a best practice, first use an ISV zPDT in a simple, non-virtual, non-container environment to establish basic familiarity and operating skills. Linux memory management, especially in virtual or container environment, can be a more complex topic than many desktop users appreciate.
Must my IBM zSystems applications be modified to test them on an ISV zPDT system
In general, the answer is no. In fact, rather specialized low-level programming is needed for a program to detect that it is running under zPDT emulation. However, this answer assumes that your applications reasonably fit the speed, the memory size, and the available disk space on the PC platform being used, and that you can handle whatever internet connections are needed.
I need multiple IBM zSystems disks for my own programs and data: Is this scenario possible
Yes. The ADCD z/OS system has some available space on the various operating system volumes, but you can create many more “work” or “data” volumes. Assuming that you have sufficient PC disk space and memory and that the workload is reasonable on your ISV zPDT system, you can create dozens (or hundreds) of additional emulated IBM 3390 volumes. Each volume can have (3390 style) 1 - 65 K cylinders for normal volumes, or be much larger for extended address volume (EAV) volumes.14 How many emulated IBM 3390 disk volumes might be practical? The answer depends on PC disk space and a detailed understanding of your workloads. There is no standard formula.
ISV zPDT provides two methods for copying 3390 volumes from a “real” IBM zSystems system. Both methods depend on network connections (or optionally, USB flash drives in one case) and do not involve a “live” ISV zPDT operation.
Can I attach a “real” IBM 3390 volume or control unit to ISV zPDT
The simple answer is no. There are no hardware IBM zSystems channel adapters for
ISV zPDT.
How large is the ADCD z/OS system, disks, and memory
Memory size for z/OS (on a “real” IBM zSystems machine or as defined for zPDT) typically starts around 4 GB (or 8 GB for a “real” system), but is usually considerably larger. How large? The answer depends on the workload. A reasonably skilled z/OS administrator, after understanding your workload, can help with guidelines.
At the time of writing, the more basic form of the z/OS ADCD system needed 15 - 28 disk volumes, depending on certain choices.15 A few more volumes are needed if you want Db2, IBM CICS, IMS, or other specialized options. These volumes are usually IBM 3390-9 volumes (8.5 GB each). In addition, volumes for your programs and data might be needed.
Is my data secure on zPDT and as secure as on a “real” IBM zSystems system
Maybe, but unlikely. You must ensure absolute security for the base PC and the base Linux, manage z/OS running under zPDT (usually through IBM RACF®), and not install the same cryptographic adapter master key that is used on the “real” IBM zSystems system. You also must manage access to the zPDT token license. In principle, all these tasks are possible. In practice, it is unlikely. As a best practice, do not move confidential data to a zPDT system. Again, ISV zPDT is for software development and testing, which typically does not involve confidential production data. Another aspect involves “backups” for your Linux system. Anyone who can access the backups can potentially access any of the emulated
IBM zSystems volumes that are part of the backup.
Can ISV zPDT be an expanded system
“ISV zPDT sounds good. I need to concurrently run 5 or 6 copies of z/OS, and a few copies of VSE, and perhaps two CF versions. How much memory do I need? Which PC server?”
This setup might or might not be reasonable for an ISV zPDT solution. IBM zSystems system emulation on a PC (such as ISV zPDT uses) is possibly not a good choice for an environment this large and complex, depending on more detailed information about your software, general environment, and usage patterns. Having stated this warning, some ISV zPDT customers do operate rather complex, large systems. although they are based on appropriate planning and testing. Contact an IBM representative or a zPDT vendor about your specific needs.
How many IBM zSystems CPUs can I create with zPDT: More CPUs allow more work
A single instance of ISV zPDT can have up to eight emulated IBM zSystems CPUs. (Some of these CPUs can be configured as IBM zSystems Integrated Information Processor (zIIP),
IBM zSeries Application Assist Processor (zAAP), or IBM Integrated Facility for Linux (IFL) processors, but they count toward the limit of eight. SAPs and ICFs are not possible. Emulated CFs are possible but not counted.) A zPDT license is needed for each CPU (including zAAP and IFL processors, but not zIIP processors), which might involve more than one zPDT token. The base PC must have at least as many processor cores as there are active zPDT CPUs. Multiple instances of zPDT can be used with each instance with the same limit of eight if there are sufficient zPDT licenses. Again, as a best practice, consult a zPDT representative (at IBM or ITC, for example) if you are considering a large zPDT configuration.
Consider the performance of a realistic zPDT system. For example, it is possible to have multiple z/OS systems running under z/VM or as separate zPDT instances (assuming that you have sufficient zPDT licenses). How effective this setup might be depends on the workloads on the multiple z/OS systems.
How are logical partitions handled by ISV zPDT: How many can I have
ISV zPDT does not provide logical partitions (LPARs), although some “LPAR terminology” is used. Multiple instances of ISV zPDT can be used, which provides an effect like LPARs. z/VM can be used with multiple “second-level” operating systems under it, which provides another effect like LPARs.
Specific configuration limits for ISV zPDT: Where can I find such information
“My staff says that they need 19 LAN interfaces, 427 disk drives (emulated IBM 3390 units), and some remote automatic backup or duplicate disk volumes. They say we use PAV for our disks. Is this scenario possible?”
Such generalized specifications are not applicable to ISV zPDT, although there are a few specific limitations in zPDT implementation. For example, there is a maximum of 32 connections for “local” 3270 terminals,16 and a maximum of 2048 emulated devices, but such configurations are not necessarily practical. ISV zPDT is intended for more basic software development and simple testing, and it is not intended to replicate a larger IBM zSystems system configuration.
Your staff’s example of 19 LAN interfaces might be possible, but it is outside any routine testing that is done during zPDT development. Your 427 emulated disk drives (where you did not specify the size of each 3390 volume) can be practical if there is sufficient memory and disk space on your base PC. “Remote” disk interfaces can be a complex topic with modern IBM zSystems servers, but is generally outside zPDT functions.17 At the time of writing,
ISV zPDT does not emulate PAV. The most important information that is missing from your staff’s note is a detailed understanding of the nature of the workloads that they expect to develop and test on ISV zPDT, especially where a complex configuration is involved.
Chapter 2, “ISV IBM Z Program Development Tool concepts and terminology” on page 19 provides a summary list of IBM zSystems system features and functions that are not provided by ISV zPDT.18 This summary can be useful, but it does not address an important side issue. ISV zPDT customers are assumed to have a reasonable degree of IBM zSystems system skills and the ability to set up whatever reasonable reconfiguration is needed (if any) for their programs or operating systems. However, few ISV zPDT customers have reported serious problems in this area.
Does ISV zPDT allow multiple concurrent users, and how many
Assuming the relevant IBM zSystems operating system that is running on the ISV zPDT system allows multiple concurrent users, the answer is yes, that is, multiple users are a normal situation. How many is a more difficult question. A typical ISV zPDT might have 1 - 5 (or 1 - 10) concurrent users as an example. (We assume that they are Time Sharing Option (TSO) users, but they might be related to CICS, IMS, or another application.) There is no specific maximum number, but dozens of users, for example, might not be reasonable.
I understand that z/OS needs 3270 terminals: Does ISV zPDT provide them
ISV zPDT provides interfaces for 3270 emulators, but it does not provide a 3270 emulator. However, most Linux systems (as used with the base PC for ISV zPDT) can obtain the x3270 emulator,19 which works well. (If the emulator is not included, it can be downloaded from multiple sites.) Some ISV zPDT customers use various other 3270 emulators. With proper networking, the 3270 terminal emulation does not need to be limited to Linux bases.
Are new zPDT releases or updates available and support new IBM zSystems machines
Yes, although the schedule for new releases is variable. In addition, “fix pack” releases are sometimes released. Installing a new zPDT release or fix pack is simple (and easily reversed in the unlikely event that something goes wrong with the new modules). New zPDT tokens are not required when moving to a new zPDT release. Generally, new hardware instructions that are provided by new IBM zSystems mainframes are also provided by new zPDT releases that occur after the new mainframe is first delivered.20
Can you provide a “script” for installing the base Linux that is needed for zPDT
No. The various commands and options that are needed for installing Linux vary with different Linux distributions, updates, additional Linux “packaging” that is based on one of the three formal Linux distributions that used by the zPDT developers, and on the specific set of optional functions. Some of these details are relatively minor, but these minor issues can change frequently. However, we believe that there are no special issues that are involved with the Linux base for zPDT that was used for developing that specific zPDT release.
Must my base Linux that is used for ISV zPDT have internet access
There are several answers to this question:
•Internet access is not needed for normal ISV zPDT operation when you use a zPDT token that is installed in the base Linux PC. (This answer assumes that the zPDT owner does not need internet access for specific purposes, such as connections for TSO users.)
•If a remote zPDT license server is used (or a “software” license for ZD&T), then some LAN access is needed, which can be a local LAN or the full internet, depending on various aspects of the configuration.
•During a zPDT installation or upgrade, or a base Linux installation or upgrade, a normal internet connection might be needed to obtain the necessary Linux library files. This aspect of zPDT installation can change with each zPDT release or upgrade or with various Linux distributions or upgrades.
How prepared are the ADCD z/OS system and the ADCD z/VM system
For ISV zPDT, both these systems can be installed, started, and used for basic, normal functions. The z/OS system typically includes TSO, IMS, CICS, Db2, IBM Interactive System Productivity Facility (ISPF), System Display and Search Facility (SDSF), TCP/IP functions, and various other IBM software. Neither system has detailed setups for complex, ready-to-use exercises or demonstrations. The user is expected to adjust and configure the system (and the software products) for specialized undertakings.
What IBM “support” goes with ISV PDT: IBM Help and problem resolutions
In a contractual sense, ISV zPDT is “unsupported” both for zPDT itself and for any IBM software (such as the ADCD z/OS system) that is grouped with it. In a practical sense, related zPDT questions are often informally handled in many ways, such as through web groups and forums. There is no direct contractual “support” for ISV zPDT ADCD z/OS questions, so customers are expected to have their own relevant z/OS or z/VM skills. In addition, there are web groups and forums that can be helpful in many areas.
More “support” can be available for ZD&T customers, depending on the specific nature of the ZD&T contractual arrangement. Also, many support options are available through ITC.
Can I maintain earlier programs, z/OS systems, and IBM zSystems machines
At the time of writing, new ISV zPDT distributions only emulate IBM zSystems machines. IBM does not maintain or provide older zPDT versions that emulate older IBM zSystems machines. Likewise, ADCD z/OS distributions are based on the version of z/OS at the time of writing. If you obtain older zPDT versions and older z/OS versions, they might require older base PC Linux versions and older PC hardware. In principle, you can use this approach, but there is no IBM assistance for doing it.21 Also, zPDT can emulate IBM 3380 and 3390 direct access storage device volumes, but it cannot emulate older direct access storage device volumes.22
Can my ISV zPDT system share data with my company’s PCs
zPDT emulates an IBM zSystems machine. Much of the data on an IBM zSystems machine is in Extended Binary Coded Decimal Interchange Code (EBCDIC) format, but it can include multiple forms of floating point data, ASCII, Unicode, packed decimal data, and many binary formats. These formats are not typically used by PCs. There are techniques for communication between an IBM zSystems system (“real” or zPDT) and PCs, but they seldom appear as “universal” sharing of data. You can upload or download files, for example, from one platform to the other, but the usefulness depends on the specific format of the data involved.
What happens if I let the zPDT token expire
A zPDT token contains the licenses that are needed to run zPDT. Each license has an expiration date. If the license expires, then zPDT stops operating. Your PC or your data is not erased, but a zPDT stoppage might affect whatever data is being processed at that specific time. Normal zPDT usage involves renewing token licenses through a relatively simple email or web process.
My staff says I need zPDT, but I do not understand many of the terms here
The text in this introductory chapter uses many terms and abbreviations that should be familiar to users with IBM zSystems system experience, but it might be a bit obscure to others. There are different levels of such experience, for example, COBOL programmers, database developers, systems programmers (or “administrators”), and production operators. The ISV zPDT products are primarily oriented toward users with IBM zSystems background skills. You might want to review this material with your staff members!
Also, there are more detailed technical questions and answers that are covered in Appendix A, “FAQ” on page 361.
Extended operation
“My staff reminded we that we need our development systems to run for extended periods, perhaps weeks or months without any interruptions or downtime, with remote users having solid access. Is this practical?”
Maybe. The primary target for ISV zPDT design is basic development operations, such as programmers entering programs, compiling them, and then performing unit tests, probably by using 3270 ISPF interfaces. This approach is not quite what your staff is specifying. Also, perhaps some investigation into the “development and test” contractual issues might be appropriate.
Nevertheless, some ISV zPDT customers routinely operate in modes somewhat like what your staff requested. ISV zPDT is a lightly support Linux application package, and it does not offer the solid architectural base of a “real” IBM zSystems system.
Does this IBM Redbooks publication represent a contract for obtaining zPDT
No. This publication can be helpful for understanding and using zPDT products, but it does not represent a contract or provide the contractual agreement that is needed. IBM Redbooks publications, including this one, are generally based on experiences by a group (often including both IBM employees and IBM customers) that use the relevant products.
What is in the rest of this publication
This IBM Redbooks publication is not intended to be read from front to back. Various chapters and topics are intended for reference only when handling specific situations. This publication covers the following topics:
•Chapter 2, “ISV IBM Z Program Development Tool concepts and terminology” on page 19 contains a more detailed description of ISV zPDT characteristics, modules, tokens, PCs, Linux directories, previous ISV zPDT releases, performance elements, and others. It does not contain detailed “hands-on” directions for system usage.
•Chapter 3, “Device maps for ISV IBM Z Program Development Tool” on page 49 describes the device maps (devmaps) that are used to configure an ISV zPDT operational environment. This information is critical for creating an operational ISV zPDT environment.
•Chapter 4, “ISV IBM Z Program Development Tool commands” on page 71 describes
ISV zPDT commands, that is, commands that are issued through the PC base Linux to configure, control, or manage the ISV zPDT operation. There are many of these commands, although the typical ISV zPDT operation involves only a few of them.
•Chapter 5, “ISV IBM Z Program Development Tool installation” on page 125 describes the specific steps that are needed to install ISV zPDT.
•Chapter 6, “Application Development Controlled Distribution installation” on page 137 provides a brief overview about installing an ADCD z/OS system and the procedures for starting and stopping it.
•Chapter 7, “Local area networks” on page 149 provides information about configuring LAN connections for ISV zPDT and for direct LAN connections to an ADCD z/OS. The total view of several techniques can be a bit confusing, and this chapter might provide difficult reading for some users.
•Chapter 8, “ISV IBM Z Program Development Tool licenses” on page 179 describes handling of ISV zPDT licenses (from tokens), and includes extended options for remote token or license operation. Multiple token (license) options also are described. Many basic ISV zPDT users are probably not involved with these details.
•Chapter 9, “Other IBM zSystems operating systems” on page 201 describes
IBM zSystems operating systems other than z/OS, mostly involving IBM z/VM. A few practical details about z/VM usage are included.
•Chapter 10, “Multiple instances and guests” on page 215 provides a brief description about multiple ISV zPDT instances. This topic is a relatively complex one that is of concern for a small set of ISV zPDT customers.
•Chapter 11, “The awscmd device manager” on page 227 describes the awscmd function, which is a pseudo-emulated tape drive that can send simplified commands from within
ISV zPDT to the base Linux.
•Chapter 12, “Minor z/OS notes” on page 237 contains notes about minor z/OS options or techniques that are referenced by typical ISV zPDT users.
•Chapter 13, “Additional ISV IBM Z Program Development Tool notes” on page 273 contains minor ISV zPDT notes about specialized topics.
•Chapter 14, “Tape drives and tapes” on page 303 contains limited material about using PC hardware tape drives with zPDT.
•Chapter 15, “Direct access storage device volume migration” on page 313 contains information about moving (“migrating”) disk contents from a “real” IBM zSystems to emulated IBM zSystems volumes on ISV zPDT.
•Chapter 16, “Channel-to-channel” on page 323 describes emulated channel-to-channel (CTC) operations between two ISV zPDT systems.
•Chapter 17, “Cryptographic usage” on page 331 provides some basic cryptographic function usage. This specific information might change with new ADCD releases, and the reader is assumed to have some IBM zSystems cryptographic skills.
•Chapter 19, “Problem handling” on page 355 contains a brief description about ISV zPDT problem reporting and handling.
•Appendix A, “FAQ” on page 361 contains many brief question and answers that frequently arise in ISV zPDT classes and reviews.
•Appendix C, “Generation 2 tokens and licenses” on page 379 describes Generation 2 tokens for ISV zPDT and IBM ZD&T.
•Appendix D, “IBM Z Development and Test Environment notes” on page 387 describes some differences between ISV zPDT and IBM ZD&T.
•Appendix E, “Secure x3270 connection” on page 391 describes a setup for encrypted usage of the x3270 terminal emulator.
 
1 zPDT is also used with IBM z/VSE®, although this scenario is not formally tested by the zPDT developers.
2 The name is often rendered as “Product Development Tool” instead of “Program Development Tool.” The extended full name is seldom used and either version conveys the concept of the actual tool.
3 The qualification to be included in this limited set of software developers is complex and must be reviewed with the appropriate IBM representatives.
4 The terms core zPDT and base zPDT often have the same meaning.
5 Throughout this publication, zPDT processors mean emulated IBM zSystems processing units, also known as Central Processor Units (CPs or CPUs). For this publication, it does not mean a physical “chip” that might contain multiple “cores.”
6 There are ways to run Linux subsets within a Microsoft Windows base, but they are not tested for zPDT, and there is no organized zPDT support for this environment.
7 This approach involves a special license in the token to enable z/VM to provide the Coupling Facility (CF) function.
8 The amount of PC disk space that is required might vary over a wide range depending, for example, on the exact nature of your z/OS disk layout (if z/OS is used) and on how much space that you need for your own emulated 3390 volumes.
9 Customers using only Linux for IBM zSystems might see this IBM software topic differently.
10 Some basic skills differ, such as controlling a system start and the initial start of an operating system. These functions are much simpler on a basic zPDT system.
11 zPDT is sometimes used for z/VSE. For more information, check with your z/VSE provider.
12 The older term was “systems programmer” or “sysprog”, but “administrator” is the current terminology.
13 These issues sometimes include Linux library level changes, library directory changes, LAN and firewall administrative changes, and others. Such changes can require corresponding zPDT administrative changes that might not be immediately obvious.
14 If “EAV volume” is an unfamiliar term, you might want to read about it on the web. A 1 cylinder 3390 volume would be unusual, but is possible.
15 A much smaller disk environment for z/OS can be practical. The number of volumes that are mentioned here reflects the current ADCD version of z/OS.
16 The meaning of “local” 3270 connections (in zPDT, the emulation of such connections) has specific meanings for people familiar with IBM zSystems servers. There is no specific limitation for OSA-connected terminals.
17 NFS can be used for “remote” disk connections if the response times are good, but it only provides more disk space. RAID functions can be used at the PC hardware level, which is not apparent to zPDT.
18 Some of the topics in the list can be considered “high level”, and a basic understanding of the topic might be needed to explore practical details.
19 x3270 is an open source program that is maintained by Mr. Paul Mattes at the time of writing. It is not an IBM product.
20 Not all new instructions might be provided. Excluded instructions are typically specific functions that might be used only by the operating system. Thus far, such limitations have not prevented general usage of the
IBM zSystems operating systems.
21 A few, long-time ISV zPDT customers use this approach by accumulating, over the years, older zPDT releases, older ADCD z/OS releases, older base Linux versions, and older PC hardware.
22 IBM 3380 emulation is provided by zPDT, but it is rarely used.
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