The following frequently asked questions (FAQs) and discussions might be helpful to newer Independent Software Vendor (ISV) IBM Z Program Development Tool (IBM zPDT)
(ISV zPDT) users.

Q: Many of the zPDT modules and commands are named aws****. What does “aws” mean?
A: It stands for Advanced WorkStation. It is an IBM convention that such things as program module names start with an identified prefix, and “aws” was chosen for zPDT.

Q: You say “ISV zPDT” almost everywhere in this publication. Can any of the materials be used for IBM Z Development and Test Environment (ZD&T)?
A: Most of it can, but you might require specific IBM ZD&T information and documentation. The two primary zPDT products are not always synchronized for changes, and they can differ in various details. This publication is mostly specific to the development level of the ISV zPDT version.

Q: For some years, I saved the z/OS Application Development Controlled Distribution (ADCD) files (in gzip format) on DVDs. However, I seem to have problems now. Why?
A: DVD formats, as generally used on Linux systems, cannot handle files larger than about 4.2 GB. More recent z/OS ADCD systems sometimes have compressed files larger than this amount, which creates errors or failures when attempting to “burn” the file on a DVD. USB flash drives, in their typical format when purchased, can have the same problem. It is possible to change the format of a USB flash drive (to ext4, for example) to avoid this problem.

Q: Is this system a multi-user one?
A: Yes. Multiple Time Sharing Option (TSO) users can connect in several ways and use the system in a normal manner. The same applies to z/VM users, CICS users, and others.

Q: How many users can the system support?
A: There is no definitive answer. The aws3274 device manager supports 32 connections (it emulates local 3270 devices). There is no specific maximum for TCP/IP (awsosa) connections to z/OS. Practical performance is the primary limitation, not the theoretical connectivity for terminal connections. A system might do well for one heavy IBM Db2 or Java user, 10 - 20 typical TSO users, or 100 web users with a low transaction rate to a z/OS web server. The answer to the question depends on the nature of the workloads that are involved.

Q: On my Linux system, I log in as root and then su to another user ID when necessary. For example, I use su ibmsys1 when using ISV zPDT. Is there a problem with this process?
A: As a best practice, do not do this action. Operating as root when it is not necessary is a security risk. Also, you must understand the difference between su ibmsys1 and su - ibmsys1.¹ The first version (without the “-” character) retains root’s environment while working as ibmsys1. The second version (with the “-” character) switches to the ibmsys1 environment, which is the version that should be used if you really must log in as root.

Q: When using a remote license server, are there any security exposures?
A: This topic is complicated. As a security measure, starting a fix for ISV zPDT GA10 remote license server access is done with HTTPS instead of HTTP.

Q: IBM zSystems Integrated Information Processor (zIIP) processors are now “free”, but
IBM zSeries Application Assist Processor (zAAP) processors are not. Why?
A: The usage of zAAPs is deprecated and does not apply to IBM z14 or later.

Q: Will adding zIIPs make my system faster if I have sufficient cores?
A: Maybe, depending on the workload. However, with some z/OS parameter combinations (in workload manager (WLM)), if zIIPs exist, some workloads are forced to run only on zIIPs, even if there are idle CPs. (Recent z/OS ADCD releases have such parameters.) This topic is a complex z/OS topic that is not unique to ISV zPDT.

Q: Chapter 8, “ISV IBM Z Program Development Tool licenses” on page 179 is a bit confusing. Are hardware tokens being replaced with “software” licenses?
A: No. At the time of writing, the “software-only” licenses are only for IBM ZD&T. In general, the software-only license servers are more complex to install and manage, and might have additional fees that are associated with them.

Q: Can I install (with gunzip) another z/OS volume while ISV zPDT is running?
A: In principle, yes. In practice, it is not a good idea. Disk usage during the compression of a volume is intense and can generate Missing Interrupt Handler (MIH) messages from z/OS.

Q: Does the number of ISV zPDT licenses that are available (assuming a remote license server) equal the number of IBM zSystems serial numbers that are assigned?
A: No. For more information, see 8.4, “General ISV zPDT client and server details” on page 184.

Q: I purchased an extra ISV zPDT license to configure a zIIP. What has changed in
ISV zPDT?
A: A zIIP no longer needs a separate ISV zPDT license. You might use your extra license to configure an extra CP.

Q: Can I install (decrypt) the z/OS ADCD residence volume from the relevant IBM site (intended for users with 1090 tokens) while using a 1091 token (or software license equivalent)?
A: No. The appropriate token (1090 or 1091) must be used with the appropriate z/OS ADCD (or other authorized) distribution.

Q: Can a z/OS program easily detect whether ISV zPDT or IBM ZD&T is being used?
A: In both cases, the emulated IBM zSystems CPs specify model type 1090. In a practical sense, one might determine which is being used by considering direct access storage device volume serial numbers, parmlib contents, and others, but this technique assumes an understanding of the practical layout of the two packages.

Q: Are new IBM zSystems processor instructions (as provided with recent new IBM zSystems machines) present?
A: Yes. The emulated instruction set matches the architectural level state for a release of
ISV zPDT. A few instructions dealing with functions that are not present in an ISV zPDT environment are not available. In rare cases, ISV zPDT might defer implementation of an especially complex instruction to later releases of ISV zPDT, but this situation should not inhibit “normal” usage of z/OS.

Q: In one place, you say that more cores than CPs are required, but in another place, you say that an equal number is required. Which is correct?
A: The number of cores must be at least equal to the number of CP + zIIP + IBM Integrated Facility for Linux (IFL) + zAAP processors. Use more cores than CPs+zIIPs+IFLs+zAAPs to provide better performance.

Q: Do I need to change any z/OS parameters to operate with ISV zPDT?
A: In principle, this situation is unlikely. In practice, you might need to adjust a few parameters that are primarily related to performance. For example, the CICS transaction timeout value might need to be increased for “heavy” transactions. Obviously, adjustments might be needed for widely different configurations. For example, moving a large Db2 application from a
1000 GB logical partition (LPAR) to a 16 GB ISV zPDT laptop might lead to difficulties.

Q: I have ISV zPDT and a hardware key. Where can I download z/OS?
A: z/OS (or any other IBM zSystems software) is not part of the core ISV zPDT program. For more information, contact your ISV zPDT provider.

Q: Do I need the hardware token to install ISV zPDT?
A: No, you need it only to run ISV zPDT or install ADCD z/OS initial program load (IPL) volumes.

Q: Can I use ICKDSF with the ANALYZE function for emulated CKD volumes?
A: No, in most cases. Emulated CKD devices (such as 3390) do not contain spare cylinders and diagnostic cylinders that might be required for the ANALYZE operation. The ISV zPDT command alcckd -rs /z/B3RES1, for example, performs a slightly similar function to verify that the basic 3390 track formats are correct on a volume.

Q: How accurate are the IBM zSystems time-of-day (TOD) and timer functions?
A: To a large extent, they are approximately as accurate as the timer in the underlying personal computer (PC). Some interval measurements might have a granularity of about
500 microseconds (plus the IBM zSystems operating system time that is needed to manage time-related activities). Do not depend on fine timing measurements on ISV zPDT to reflect what timing might be on a larger IBM zSystems system. Also, when a heavily loaded ISV zPDT system runs for a long time, there might be a slight loss of synchronization between the base PC TOD and the computed ISV zPDT TOD.

Q: I need to have multiple levels (more than three) of z/OS available for testing, although each z/OS is usually idle at any time. A 1090-L03 seems to be too much for my modest processing needs and is limited to three instances. How can I address this problem?
A: The easiest solution is to use z/VM with multiple z/OS guests. This solution requires some z/VM skills. The solution requires more IBM zSystems memory than other potential solutions to avoid excessive z/VM and z/OS paging. (For more information about older z/OS releases, see 3.2, “System stanza” on page 50.) Memory is important for reasonable performance in such situations. However, you must be sensitive to the architectural level of the ISV zPDT system that you are using. For example, the IBM z14 level (ISV zPDT GA8 and GA9) cannot be used with older operating systems that do not support this level. Also, “overloading” your ISV zPDT environment can create performance and reliability issues.

Q: Why do you not provide a definite million instructions per second (MIPS) or MSU value? These values would help me determine how to best use ISV zPDT.
A: There are no definite numbers. A MIPS measurement depends on the exact workload and your system configuration. A workload description like “I have six TSO users” is useless.

Q: Why do some ADCD releases pause for many seconds while shutting down?
A: You can edit the SHUTDOWN entries in PARMLIB to remove or change any pause statements. Some functions, such as zFS, have built-in delays that we cannot change.

Q: You are inconsistent with the addresses for the ADCD volumes. For example, sometimes volume SARES1 is at address A91 and sometimes at address AA0. Which is correct?
A: Both are correct. Any 3390 volume can be at any address that is defined as a 3390 in the input/output definition file (IODF) for that z/OS system. For ease of documentation, we always show the primary IPL volume at A80 and the SYS1 volume (which contains the IODF and IPLPARM data sets) at A82, but these addresses are not required. The IPL address and parameter must match the addresses that you use. We tend to show SARES1, if mounted, at various addresses.

Q: What happens if I remove the hardware key?
A: The ISV zPDT functions stop after a while.

Q: You use user ID ibmsys1 throughout all the examples. Is there something special about this user ID?
A: No. However, you should always use the same Linux user ID when running ISV zPDT, and the user ID should not be longer than 8 characters. (If a system_name statement is used in the device map (devmap), then there is no special limit on the Linux user ID name.)

Q: Can I use an alternative translation table to convert Extended Binary Coded Decimal Interchange Code (EBCDIC) to ASCII for awsprt output?
A: No. However, the translation table was updated for ISV zPDT GA9.

Q: My z1090 rpm installation failed with an error message about db_recovery. What now?
A: Run the command rpm --rebuilddb and then install ISV zPDT 1090.

Q: I am using an emulated printer that sends output to a Linux file. Does this file remain open for output by ISV zPDT while it is running?
A: Yes. However, it is closed if you use awsmount to assign a new output file for the printer.

Q: Are ISV zPDT commands case-sensitive? Can I issue ipl or IPL?
A: The command names are case-sensitive. They are the names of Linux files, and Linux file names are case-sensitive.

Q: The z1090instcheck command does not work. Why?
A: You might need the full path name for the z1090instcheck command if your Linux PATH environmental variable does not include /usr/z1090/bin.

Q: The ADCD z/OS system always starts TCP/IP and associated jobs. How can I delete them?
A: You can edit the VTAMAPPL types of entries in PARMLIB and remove the associated start commands. While running z/OS, you can issue P TCPIP. You might need to cancel address spaces that are related to TCP/IP, such as INETD1.

Q: Can I use IBM Resource Measurement Facility (RMF)?
A: Yes, but not all of RMF is relevant on an ISV zPDT system, and some functions might be misleading.

Q: How do I perform an IPL of the SARES1 volume?
A: Assume that it is mounted at A9C. The command is ipl A9C parm 0A9CSA. Use S SHUTSA to shut down the SARES1 system. (The system can be mounted at any address that defined as a 3390 in the ADCD IODF.)

Q: Why is the first part of the z/OS IPL sequence a little slow under z/VM? After this portion is complete, z/OS seems to run at a more normal speed under z/VM.
A: This situation is due to memory initialization and management functions being initialized through multiple virtualization paths (virtual machine (VM), START INTERPRETIVE EXECUTION (SIE), and Linux). The time seems related to the defined z/OS guest memory size and disk cache performance. The effect is less apparent when larger PC memory is available or solid-state drives (SSDs) are used.

Q: I want to place Db2 buffers in the Coupling Facilities (CFs) in my Parallel Sysplex. Also, I want to put the Job Entry Subsystem (JES) 2 checkpoint data and RACF data there. How do I do this task?
A: These tasks are beyond the scope of this publication. Study the appropriate manuals and seek help from a systems programmer with experience in this area. You might also need to change the CF definitions memory sizes in the z/VM directory.

Q: I crash my ISV zPDT system (possibly with the awsstop command). Can I continue to take this action with the Parallel Sysplex running?
A: You can do it, but starting the Parallel Sysplex again might be difficult. Follow the normal shutdown procedures for a Parallel Sysplex. In particular, use the V XCF,xxx,OFFLINE command to stop more z/OS members of the sysplex.

Q: Why is the z/OS TOD clock (or the z/VM TOD clock) at least 27 seconds different than the base Linux clock?
A: IBM zSystems operating systems apply leap seconds to the clock, but Linux does not. The current leap seconds offset, at the time of writing, is 27 seconds. This IBM zSystems function is included with the ISV zPDT GA6 and later releases. Also, while ISV zPDT is running, additional time differences might accumulate.

Q: Can I emulate various subcapacity settings and controls?
A: No. ISV zPDT does not provide these functions.

Q: If I unplug my token, how long will ISV zPDT continue to operate?
A: The length of operation without a token (or remote license) is variable, but might be up to several minutes.

Q: I dislike Linux gnome. Can I use the Xfce desktop?
A: Yes, if you can find it for your Linux distribution. ISV zPDT is not sensitive to the Linux desktop that is used.

Q: This publication mentions various limitations for crypto usage. Will these limitations be resolved in future zPDT releases?
A: Possibly. However, it is unlikely that all the more advanced features of IBM zSystems system cryptoadapter functions will be emulated.

Q: Can I run z/VM, two z/OS guest machines, and a CP guest machine with only one PC processor (“core”) and one ISV zPDT CP?
A: Yes, in theory. z/VM shares the processor with all the guest systems. However, this configuration can produce timeouts within z/OS. We consider it below the minimum level for practical use.

Q: Is a Parallel Sysplex system practical on a laptop?
A: Yes, but ensure that you have sufficient PC memory. Use 16 GB as a minimum in this case.

Q: I see that the z/OS ADCD system has IBM 3380 devices at some addresses. Do I need them?
A: These devices are present mostly for historical reasons, although it is possible that a few users need them for older software. Do not use them unless you must use IBM 3380 direct access storage device.

Q: Does IBM need to enable something to allow full operation of the IBM zSystems system internal crypto instructions?
A: No, full operation is always enabled.

Q: The basic ISV zPDT setup looks easy, although I realize the networking can be a challenge. However, reading Chapter 16, “Channel-to-channel” on page 323 (for simple JES2 networking, for example), Chapter 18, “Server Time Protocol” on page 347, or Chapter 17, “Cryptographic usage” on page 331 is confusing. Are these functions needed?
A: Good question. The cryptographic functions are used by a reasonable subset of ISV zPDT customers but are not “required” unless you have applications (programs or z/OS elements) that need them. The CTC information is used by few users, and the STP information by almost no one. They are included because they are part of the current IBM zSystems system basic design.

Q: Should device statements (in a devmap) be in order by addresses?
A: No particular order is required.

Q: I have volumes at addresses A80 - A8F. Do I need to define a new awsckd unit to add more disk volumes?
A: No, you can have up to 256 volumes in one instance of awsckd.

Q: All your examples have 3-digit emulated device addresses. Are they required?
A: No, you can use 3- or 4-digit addresses. The typical usage of only 3-digit addresses with the ADCD z/OS system is a historical accident.

Q: Can I use multiple ISV zPDT tokens to obtain more CPs?
A: Yes, up to a maximum of 8 CPs in an ISV zPDT instance. In this context, zIIPs, zAAPs, and IFLs count toward the limit of 8.

Q: Can ISV zPDT support older CKD drives, such as 3350?
A: No.

Q: Can I use MVS 3.8?
A: No. The ISV zPDT system does not support architectures before XA and 3380 and 3390.

Q: Can I configure ISV zPDT to act as, for example, a z800 system?
A: No. Each ISV zPDT release matches a specific IBM zSystems architecture. ISV zPDT GA8 matches IBM z14 systems, for example. There is no ISV zPDT facility to alter the architecture level.

Q: Is Flashcube supported for emulated disks?
A: No.

Q: Can emulated printer output be directed to /dev/lp0 or similar?
A: We do not know because this scenario was not tested.

Q: What are the maximum numbers of CPs, ISV zPDT instances, and I/O devices?
A: A maximum of 8 CPs (or combinations of CPs, zIIPs, zAAPs, and IFLs) can be used in an ISV zPDT instance, although your license terms might have a lower limit. A maximum of 15 ISV zPDT instances can exist in a Linux system if you have sufficient licenses. A maximum of 2048 I/O devices can be defined in an instance. Do not take these program maximum values as being practical environments. There are other factors (such as available memory, SMP effects, and I/O capability) that limit practical usage to much smaller configurations.

Q: Can I move an ISV zPDT token between two PCs?
A: Technically yes,² but there is an important issue that is involved. The latest TOD value that is seen by the underlying PC hardware is stored in the token. If the token encounters an earlier time, it fails the operation with a time cheat message. If your two PCs have a significant time spread between their hardware TOD clocks, you might have problems.

Q: You have a whole chapter on STP and Coordinated Timing Network (CTN) (TOD functions) (Chapter 18, “Server Time Protocol” on page 347). Are these functions typically used with ISV zPDT?
A: As far as we know, they are rarely used with ISV zPDT. They are part of the IBM zSystems architecture and are included in ISV zPDT for this reason. Unless you have a specific requirement, do not experiment with these functions.

Q: Why do you support only limited Linux releases?
A: IBM performs extensive testing for ISV zPDT. We use Linux releases that are current at the time that a release development starts. There are many practical reasons for not changing the Linux level midway in the development cycles.

Q: I have several Linux windows open while running ISV zPDT. I can enter ISV zPDT commands in any window, which is convenient. However, I also sometimes get output messages in a different window from where I entered a command. Is this normal?
A: Yes. ISV zPDT output messages (but not command output messages) are sent to the console session that issued the awsstart command.

Q: Can I make the kernel.shmmax value large to avoid worrying about it?
A: As far as ISV zPDT is concerned, you can. However, it is possible that other Linux applications might accept the large value and attempt to use unreasonable amounts of shared virtual memory, which results in excessive paging or system failure.

Q: Why is ISV zPDT placed in /usr? This directory should be only for basic Linux components.
A: You are correct, but it is difficult to change that situation.

Q: Can I run as root when installing and using ISV zPDT?
A: Yes, for part of the installation process. No, for operation. Follow the instructions concerning when to work as root and when to work under a normal user ID (such as ibmsys1).

Q: Does ISV zPDT operate in kernel mode? In suid mode?
A: A few administration modules operate in suid (root) mode. However, these details might change with future ISV zPDT releases. Starting with ISV zPDT GA10.2, there is no Linux root authority that is required during routine ISV zPDT operation.

Q: Can I routinely migrate to the next Linux releases when they become available?
A: Maybe. There is no unique ISV zPDT tie to a particular release, although the Linux release should be the same or later than the ISV zPDT “build” level. However, it is possible that the ISV zPDT installation steps might not work for a new release (due to different library paths or levels) or that the new release might not support the particular hardware in your base machine. Contact your ISV zPDT provider.

You are probably safe going to a new minor distribution release. For example, going from Red Hat Enterprise Linux (RHEL) 7.3 to RHEL 7.4 should be safe. It is a best practice to not jump to a new major distribution such as from RHEL 7.x to RHEL 8.x that is not listed as a “Base” level in 2.5, “ISV zPDT releases” on page 44. Our experience is that minor ISV zPDT installation adjustments are sometimes needed for new major Linux release levels.

Q: Is there any Linux checking that should be routinely done?
A: You should check your /tmp file system from time to time and ensure that free space is available for it. You might check your Linux home directory for ISV zPDT, which is /home/ibmsys1 in our examples and delete any core files. The core files can be large and are unwanted unless you are actively debugging a problem. Core files in the ISV zPDT subdirectories should be investigated.

We have no specific recommendations about online updates to your Linux base system. In earlier years, we avoided these updates because of various problems that were introduced through them. More recently, some members of the ISV zPDT development team have been routinely doing online updates of their Linux (when ISV zPDT is not running) without experiencing problems that are related to the updates.

Q: Can I use compressed disk files or sparse files to reduce the amount of disk space that needed by z/OS volumes?
A: ISV zPDT does not support any form of compressed disks or files, or Linux sparse files. If you have a compressed disk scheme that is transparent to ISV zPDT, you can try it.

This section has frequently asked questions about the following topics:

SCSI tape drive support was dropped in ISV zPDT GA 10.1.

Q: I have a SCSI tape drive. I want to use it directly for Linux functions that are not connected with ISV zPDT operation, but I cannot find the mt command (a “standard” Linux command for manipulating tape devices).
A: We noticed that mt is not always installed with some Linux distributions. In some cases, it appears to be part of the cpio rpm.

Q: Can I use a SCSI digital linear tape (DLT) tape drive?
A: It should work if it supports the SSC-3 SCSI Command Set for Sequential Devices, although this scenario is not supported by IBM and has not been tested.

Q: Can I use a SCSI 4 mm tape drive?
A. It might work, but it is a best practice to not use 4 mm drives because they are poorly suited for emulated IBM S/390 work.

Q: Can awstape files from P/390 or R/390 systems be used with the ISV zPDT offering?
A: In general, yes. There is a restriction that the P/390 or R/390 awstape file cannot be read beyond the last valid logical data record. The older awstape files do not contain the proper indicators after the last logical data record. (However, awstape files that are created by
ISV zPDT work correctly in this situation.) This situation is typically encountered when using “tape map” programs that attempt to read everything on a tape without obeying the normal EOV/EOF records or double tape marks that normally are used to indicate the logical end of data on a tape.

Q: How can I write a tape mark on an awstape volume?
A: Use awsmount xxx --wtm, where xxx is the address (device number) of the tape drive. There is a double dash before the wtm option.

Q: When performing an IPL of z/OS, I see messages beginning with “CU AUTHORIZATION FAILED...” for my 3390 emulated disk drives. What do these messages mean?
A: Ignore the messages. They occur because of emulation difficulties that do not affect the operation, and they will eventually be fixed.

Q: Most of the documentation is about large laptops or servers. I have a typical desktop PC. Can I use ISV zPDT with it?
A: Probably, assuming Linux works properly with the display, DVD drive, power, and local area network (LAN) interfaces on your desktop. You should have at least 8 GB of memory (more is better). However, the only formal support is for the machines that are described in this publication. IBM cannot undertake the extensive testing that would be needed to qualify the vast variety of PCs that exist.

Q: Can I use the Linux taskset command to bind a Linux core to an ISV zPDT CP? Would this setup make the hardware caches more efficient?
A: The ISV zPDT developers have not tried this action. The taskset command can bind a Linux process to a particular core, but it does not prevent other processes from being dispatched on that core, thus locking out the CP process that is bound to that core. Also, there are many ISV zPDT processes for I/O operation and Just In Time (JIT) functions. In a situation with sufficient cores that are available, you might improve ISV zPDT performance slightly, but this task probably would take considerable experimentation and be sensitive to a particular workload. Attempting to automate such tuning for all ISV zPDT installations and workloads can become complex and possibly degrade performance instead of enhancing it.

Q: Does ISV zPDT reserve PC processor cores for IBM zSystems emulated execution? Does it partition PC memory in some way to create IBM zSystems memory?
A: No. (See the prior question about the Linux taskset command.) A running ISV zPDT system consists of many processes and threads under Linux, which are dispatched in the normal Linux manner and reference Linux virtual memory as a normal application.

Q: Are two or more processor cores needed? Can I use a PC with a single core?
A: Two processor cores are not required for an L01 system. Working with a single core results in a slower system because the single processor must handle all IBM zSystems CP operations plus all the other processes for I/O and other Linux details.

Q: I am short on USB ports. Can I use a USB extender for the token connection?
A: Do not use an unpowered USB port extender because it might render your ISV zPDT token unusable. A powered USB port extender should work correctly.

Q: Can I use a USB disk drive for emulated IBM zSystems data?
A: Yes, assuming the base Linux recognizes and supports the drive in the normal manner. The drive might offer slightly less performance than the internal PC disk drives, but this situation might be acceptable in many cases.

Q: Should I use AHCI or compatibility mode for the laptop disk?
A: Linux seems to install correctly either way. However, we have reports that setting AHCI (in BIOS) instead of Compatibility mode greatly improves performance of Ultrabay disks, but we do not have more exact information about specific configurations. ISV zPDT does not care about these settings because it uses Linux I/O functions.

Q: Does more PC memory improve performance?
A: Yes, up to a point. Linux can effectively use memory as a disk cache, which enhances performance.

Q: Is there an adapter for parallel channels?
A: At the time of writing, there are no hardware channel adapters for ISV zPDT systems.

Q: I have ESCON adapters from previous products for my Intel base PC. Can I use them?
A: No.

Q: Can a solid-state drive (SSD) be used (on the PC) instead of a traditional hard disk drive (HDD)?
A: Yes, they are effective.

Q: You frequently mention that paging should be avoided. Can I install more PC disks to reduce bottlenecks in this area?
A: We do not know. We doubt that another disk in a laptop or USB port would have much effect. More SCSI drives on a larger server, especially with multiple SCSI adapters, might help. We are interested in any documented experiences in this area.

Q: I am using the emulated crypto adapter, but RMF says that there is no adapter. What am I doing wrong?
A: RMF uses a CHSC command to obtain statistics from a crypto adapter. At the time of writing, ISV zPDT does not support this usage of the CHSC command. Use other means to verify that the crypto adapter is working as expected.

Q: I sometimes see a message beginning AWSSTA138E TERMINATE CPU-0 FAILED, RC=43. What does this mean? What should I do?
A: This message means that the zPDT license (typically from a token) was not obtained correctly or that it did not complete the initialization of the emulated CPU. You can check that your token license is valid; the token is correctly installed; and then try starting zPDT again.

Q: How many “local” 3270 sessions can I use with ISV zPDT?
A: At the time of writing, the limit is 32 sessions with the aws3274 device manager. There is no limit on the number of sessions through z/OS TCP/IP.

Q: Can I use 3270 sessions on other PCs? Your example has all the sessions on the
ISV zPDT machine.
A: Yes. Point your 3270 emulator (on your external PC) to the Linux IP address and port 3270 (if you are using port 3270 for aws3274). Use a relatively modern 3270 emulator, such as recent versions of IBM Personal Communications or x3270. Older, “free” 3270 emulators created problems during some of the ISV zPDT test cycles.

Q: Do the int3270port and intASCIIport interfaces provide the same functions as the equivalent functions on a Hardware Management Console (HMC) that is attached to a larger IBM zSystems system?
A: This operation is the intended one, although the operational characteristics might differ. These interfaces are normally used only when needed for installing a new IBM zSystems operating system. As a best practice, do not include them in a devmap unless there is a specific need for one of them, and do not include both in the same devmap.

Q: Can I use my “brand X” TN3270e client?
A: Maybe, but do not base any error reports to IBM on it. Not all TN3270e clients are the same, and there can be differences in the handling of error and recovery situations.

Q: Does ISV zPDT handle 3270 nulls correctly?
A: This function is not one of ISV zPDT, but it is a function of the 3270 emulator and to some extent the application that is involved. Relevant functions for x3270 can be found by selecting Options → Toggles → Blank Fill. The IBM Interactive System Productivity Facility (ISPF) command nulls on|std|all|off might be relevant.

Q: I am using the IBM Personal Communications product to connect from a remote PC to z/OS running on ISV zPDT. Every time that I start Personal Communications, it wants to print something. How can I stop this action?
A: This issue is not related to ISV zPDT. Personal Communications stores user profiles in .ws files (such as bill.ws). Find the .ws profile that you are using and add the following lines at a reasonable place in the profile:

Q: I want to use Personal Communications instead of x3270. Is this approach acceptable? Can you include Personal Communications with the ISV zPDT package?
A: Personal Communications is part of a separate IBM product. We cannot include it as part of the ISV zPDT package.

Q: The --interface parameter for awsosa is confusing. How should I use it?
A: Read the material in Chapter 7, “Local area networks” on page 149. The --interface parameter was introduced because recent Linux distributions changed the way that LAN interfaces are named, so a more general method of specifying a LAN interface to awsosa might be needed.

Q: Are the 10.1.1.x addresses for local 3270 sessions required? Can I use something like 192.168.123.5?
A: The 10.x.x.x addresses are not required. They are used in our examples to represent a simple setup. You should use non-routable addresses and make the devmap addresses (for the awsosa definition) match the z/OS addresses and match the 3270 emulator addresses.

Q: Connecting from a different PC (usually with a 3270 emulator) sometimes seems to produce security problems. Any suggestions?
A: There can be many parameters that can affect this situation, such as in z/OS, RACF, OVMS, Linux, routers, the web, and firewalls. The list is long and beyond the scope of the zPDT developers and this publication. However, you can look at some basic elements, such as an xhost + command on your remote connection machine (if that command even applies to your configuration).

Q: Will my devmap from a previous ISV zPDT release work with new ISV zPDT releases?
A: Probably. An important issue concerns path names for Open Systems Adapter (OSA) interfaces. Previous ISV zPDT releases (before GA10) considered only LAN interfaces that were not down when assigning path names. At the time of writing, the release considers all detected LAN interfaces, which can result in a different path name for OSA.

Q: Can I have multiple tap (tunnel) interfaces, such as tap0, tap1, and others?
A: Yes. A total of eight OSA devices of any type can be defined. The tunnel interfaces typically are CHIPD numbers A0, A1, A2, and so forth. The tap devices can be defined (as shown in the find_io command output), but they are not used unless a corresponding OSA device exists in the devmap. You can alter the CHPID numbers by using the --interface parameter on the awsosa device manager statement.

Q: Can I run multiple TCP/IP stacks on a single ISV zPDT emulated OSA-Express adapter?
A: Yes.

Q: Why might I need to specify a unit address in the device statements for OSA? I do not understand.
A: A full discussion is beyond the scope of this publication. As a best practice, use the QDIO (also known as OSA-Express Direct (OSD)) interface, in which case the unit addresses are not needed. For non-QDIO TCP/IP, ensure that the unit addresses are 0 and 1. (This configuration is required by the default OSA Address Table (OAT) that is used by OSA.) Ensure that unit address FE is used only for Open Systems Adapter/Support Facility (OSA/SF) when using the default OAT. The default unit address is the same as the low-order 2 digits of the device number (“address”). If you meet these requirements, there is no need to specify a unit address in the device statements for OSA. However, the older administration program for OSA/SF is not available in z/OS, and the replacement program is not usable with ISV zPDT.

Q: Does ISV zPDT support thin interrupts?
A: Yes, for OSA device emulation, but not for CF communication. (This function is known as the Adapter Interrupt Facility.)

Q: Can I filter IP traffic before it is sent to my emulated OSA-Express interface? This action reduces the overhead that is involved in rejecting packets that are not addressed to my system.
A: In OSD (QDIO) mode, there is some automatic filtering. In OSA-Express (OSE) (non-QDIO) mode, you can customize the OAT with your IP address. If you do this task, the OSA interface passes only packets that are intended for this IP address.³ If this customization is not done (and it is not done in the default OAT), then all packets are sent to the host TCP/IP, and unwanted packets are rejected at that level. If you use Network Address Translation (NAT) functions on the base Linux, then most of the filtering is done at that level. At the time of writing, z/OS releases use an OAT management interface that is not supported by the zPDT.

Q: Is the OSN operation (CDLC) provided with current ISV zPDT OSA emulation?
A: No.

Q: Should I use 1492 or 1500 as the maximum transmission unit (MTU) size when using awsosa?
A: We use 1492. The details are beyond the scope of this publication. (As best we can tell, the IBM zSystems communication routines automatically adjust this number down if necessary, so it probably does not matter whether you specify 1492 or 1500.)

Q: Does current ISV zPDT QSA emulation include advanced functions such as VIPA?
A: Yes, when using QDIO.

Q: Can I use a continuing range of addresses (device numbers) when I have multiple OSA QDIO interfaces? For example, 400-402 for TCPIP1, 403-405 for TCPIP2, and so forth.
A: No. For z/OS, the first OSA address for a TCP/IP stack must be an even number. You would use 400-402, skip 403, then use 404-406, skip 407, and so forth. (This statement might not be correct for z/VM.)

Q: At the time of writing, do the ISV zPDT OSA offload functions work? Do they accomplish anything on an emulated system?
A: The Linux-based ISV zPDT OSA implementation does not use offload functions at the time of writing. In some cases, you might need to force Linux to disable offloading.

Q: What PC card (PCMCIA-type card) should I use for additional Ethernet ports on a ThinkPad?
A. Use any card that the base Linux system accepts. Some years ago, we tried an Xterasys Gigabit PC Card (98-012084-585). We also informally tried several older IBM 10/100 EtherJet cards. However, none of them are “supported” ISV zPDT options, and we have doubts about more recent Linux support for such adapters.

Q: Can I use IP aliasing in Linux while using ISV zPDT?
A: Yes, but the alias addresses are not relevant to ISV zPDT and are not displayed by the find_io command.

Q: I have multiple Ethernet adapters, each on a different subnet. The response is slow and I get multiple responses to pings. Is there a problem with using multiple adapters?
A: In principle, no. However, multiple interfaces on different subnets should not be connected to the same virtual LAN (VLAN) because it creates routing, ARP, and duplicate response issues. Also, the external routing configuration (external to your system) might produce multiple responses. Multiple subnets on a single physical network might produce multiple responses. Do not use multiple LAN adapters unless you have the necessary networking skills.

In general, an ISV zPDT owner might require networking assistance for any configuration other than aws3274 emulation on a local router, which is not a unique zPDT issue.

Q: I have an error message about Generic VLAN Registration Protocol (GVRP) when I try to use a VLAN or VSWITCH in z/VM. Is this scenario supported?
A: No, GVRP is not supported. Specify NOGVRP for your VSWITCH. VLAN generally works, but there are exceptions.

Q: Is the OSA function for Integrated Console Controller (ICC) provided?
A: No. However, the AWS3274 device manager provides approximately the same service.

Q: I sometimes want to change Linux TCP/IP between DHCP and a static IP address. Can I do this task while ISV zPDT is running? I am changing only Linux parameters, not OSA parameters.
A: This scenario is not supported or tested, and it probably will not work correctly. Do not change Linux LAN definitions while ISV zPDT is running if you are using OSA functions.

Q: Is Token Ring supported for emulated OSA usage?
A: No.

Q: Can I use the emulated OSA QDIO with IPv6?
A: Yes. In principle, you also can use it for aws3274 clients if you find a client (and Linux host) that supports IPv6. As a practical matter, there has been minimal ISV zPDT testing of IPv6.

Q: You say that Ethernet Systems Network Architecture (SNA) operation is not supported. Might it work?
A: Yes, it might. It has not been tested and IBM does not respond to problems where it is used.