Mainframe Performance Topics Podcast Episode 23 “The Preview That We Do”

(Originally posted 2019-02-27.)

This episode is hot on the heels of the previous one.

Marna set us the ambitious goal of getting it out on the day of the Preview Announcement of z/OS 2.4 – February 26th. And we succeeded. Phew!

I’m really excited about the Docker / Container Extensions (zCX) line item and I’m sure we’ll return to it – both as Mainframe and as Performance topics. Obviously, this being a Preview, that will have to wait a while.

So, I finally caved and mixed this Mono. I had no idea how I was going to do that. I hope y’all think it turned out OK.

I’m aiming to return to regular blogging soon. Right now there are things that I want to talk about but now is not quite the right time.

In the meantime, I hope you enjoy the show, and here are the notes.

Episode 23 “The Preview That We Do”

Here are the show notes for Episode 23 “The Preview That We Do”. The show is called this because we talk about the newly previewed z/OS release, V2.4, in the Mainframe section. This is our 24th episode too! How convenient! This episode is somewhat shorter than others because we wanted to slot it in for a particular date (the z/OS V2.4 Preview date) and we’d just done Episode 22.

Mainframe: z/OS V2.4 Preview

  1. “z/OS Container Extensions” aka zCX

    • Intended to enable users to deploy and execute Linux on IBM Z Docker containers on z/OS. Not just run but also to enable application developers to develop and package popular open source containers.
    • It is clear that Docker is becoming prevalent with users. Now, z/OS could leverage industry standard skills, quickly on z/OS.
    • One could pull IBM Z Linux containers from Dockerhub. Latest count was 1724 in 14 categories.
    • Martin is interested in the instrumentation, and in the SMF records. Configuration we’ll cover in a future podcast.
    • The planned preqs for zCX are: z14 GA2 or higher, and will require a HW feature code
    • zCX is planned to be zIIP eligible.
  2. z/OS Upgrade Workflow, no book

    • ”Upgrade” is the new term instead of ”Migration”
    • No z/OS Migration book, use the workflow instead. That requires you to become familiar with z/OSMF and workflows in particular.
    • Not everybody is familiar with z/OSMF, so we’ll export a workflow file and put it on Knowledge Center so you can view, search, print. However, the Workflow should give you a better experience.
  3. More in Pervasive Encryption

    • Additional z/OS data set types: PDSE and JES2 encryption of JES-managed data sets on SPOOL.
    • Without application changes, of course, and simplifies the task of compliance
  4. zfs enhancements

    • Better app availability

      • Allows app running in a sysplex and sharing rw mounted file system to no longer be affected by an unplanned outage.
      • Should no longer see an I/O error in this situation, which might have caused an application restart.
      • New mount option, and can be specifically individually or globally, and changed dynamically. New option will be ignored if specified and in a single system environment.

      • Facility BPXWMIGF enhancements planned to migrate data from one zfs to another zfs, without an unmount.
      • Previously, facility was only for hfs to zfs.
      • New function helps with moving from one volume to another volume.
  5. MCS logon passphrases

    • Through the security policy profile specification, provides more consistent, secure system environment to meet security requirements.

Biggest question one may have: what level of HW will z/OS V2.4 IPL on? z/OS V2.4 will run on zEC12/BC12 and higher.

Performance: Coupling Facility Structure Duplexing

  • Two types of CF structure duplexing:

    1. User-Managed: Only DB2 Group Buffer Pools (GBP)
    2. System-Managed: e.g DB2 IRLM LOCK1 Structure
    • The structure types for system-managed duplexing are all types: list, list serialized, lock, and cache.
    • User-Managed obviously only Cache.
    • Some structures are not duplexed, e.g. XCF.
  • Structure performance matters

    • User-Managed not an issue.
    • System-Managed matters.
  • Asynchonous CF Structure Duplexing Announced October 2016

    • Just for lock structures, specifically DB2 IRLM LOCK1. This changes the rules, and requires co-operation from e.g. DB2.
    • Functional dependencies:

      • z13™, IBM® z13s with CFLEVEL 21 with service level 02.16 or later
      • z/OS® V2.2 with PTFs for APARs OA47796 (XES) and OA49148 (RMF)
      • DB2® V12 with PTFs for APAR PI66689
      • IRLM 2.3 with PTFs for APAR PI68378
    • Important considerations if Async CF Duplexing good all the time:

      • People make architectural decisions and this should not be a leap in the dark .
      • Ideally should be established with a little testing, with testing as close to production behaviors as possible.
      • Generally it’s good for you.
    • Configuration: Format couple data set, put into service, and then REALLOCATE. Again speaks to planning and testing.

  • The main event for this item is SMF.

    • SMF 74-4 Coupling Facility Activity data, primarily interested in structure-level, especially for structure duplexing of any kind. Though CF to CF pathing information also available.
    • Information at the structure-level

      • Size and space utilization, request rate and performance for both copies in the duplexing case, and bit settings for Primary and Secondary.
      • Still use old method of comparing traffic: Rates and Sync vs. Async. It doesn’t much matter for System-Managed.
    • New Async CF Duplexing instrumentation

      • APAR OA49148
      • Asynchronous CF Duplexing Summary section. Martin has a prototype in REXX to format it that gives timings of components. It is not the same as “effective request time”. Nor are raw signal service times.
      • “Effective request time” relates to effect on application, in the SMF 101 DB2 Accounting Trace.
      • Gives sequence numbers which are important for synchronization. If the sequence numbers are too far apart might indicate a problem.
  • Early days of Async CF Duplexing despite having been announced in 2016. Martin has been using a customer’s test data, and would like to build experience. Only a portion of this new SMF 74-4 data is surfaced in RMF Postprocessor reports.

  • z/OSMF Sysplex Management can help visualize and control the Sysplex resources. This function to help with control is in PI99307: SYSPLEX MANAGEMENT APPLICATION ENHANCEMENTS TO MODIFY SYSPLEX RESOURCES.

Topics: Smart home thermostats

  • Marna just installed two Nest thermostats, one in each zone (of a three-zone house). Is sharing data with Nest, and presumably whoever owns Nest currently (Google).
  • Marna’s house is oil heating, and AC with electrity. She installed them because of her electric company incentives.
  • The electric company can control the thermostat in the summer (air-conditioning) a certain number of days, for one hour, up to five 5F degrees. Since it is winter, she hasn’t seen this happen yet of course.
  • Instrumentation benefit is having an app in which she can look at what is happening at home, when away, and control it too.
  • There are excellent graphs on what has been used (hours of heating, cooling) in the app.
  • Also, there is geofencing via your phone, where the thermostat knows you are at home (or coming home) and can set the temperature what is desired. Marna has that location turned for two phones. Nest actually has been learning the habits of what she likes for temperature and can predict what to set.
  • Marna’s electricity usage hasn’t been able to shown to be reduced yet, but then again, it is not yet summer.
  • The app also compares her usages to the neighbors (whoever they might be). House size and people at home affect usage, so it’s unclear how that plays into these usage reports.

    • It is fun to gamify with neighbors!
  • Martin doesn’t have a smart home termostat, but does have a remote oil tank sensor to determine how much oil is left. This sensor feeds back into a device in the house, and connects to an app on his phone.

    • It costs 5 GBP a month, but is unsure yet if it is worth it.

Places we expect to be speaking at

  • Marna will be at SHARE Phoenix March 11-15
  • Martin will be March 12 GSE UK zCMPA Working Group – in London, with a new alpha presentation!

Contacting Us

You can reach Marna on Twitter as mwalle and by email.

You can reach Martin on Twitter as martinpacker and by email.

Or you can leave a comment below. So it goes…

Published by Martin Packer

I'm a mainframe performance guy and have been for the past 35 years. But I play with lots of other technologies as well.

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