We were especially keen to get a podcast episode out on the day z17 was announced, having both worked on the launch project in various capacities. So, for once there was a deadline – which we actually made.
It was a pleasure to record this, with almost every piece of it related to z17.
So here are the long show notes.
Episode 36 “Telum Like It Is”
Where we’ve been
- Marna has been to SHARE in Washington, DC, February 24-27, and in March 24-28 to a select customer council in Germany to talk about future designs.
- Martin has been to Berlin (former East Berlin) for new hardware education.
Manual Of The Moment
- Actually, it’s a section of a Manual of the Moment: Software requirements for running z/OS 3.1.
- This is because this manual was refreshed when we moved our Java dependency on z/OS 3.1 from Semeru 17 to Semeru 21. Semeru 11 is EOS in November 2025.
Ask MPT
- Keith Costley of Mastercard has an excellent question about Coupling Facility and utilitization.
- Summary: My contingency SYSPLEX with shared ICF’s continually shows a utilization of 70-85% although there is not much work on those SYSPLEX’s. I don’t know if the is reporting correct? Is there a way to determine what is using up the ICF capacity if it is? Also, we have Thin interrupts turned on.
- Since this is a performance question, Martin answers: “Shared ICFs” is important here.
- CF Activity Report uses R744PBSY / (R744PBSY + R744PWAI). Works well for Dedicated but not Shared. Particularly Thin Interrupts.
- Use SMF 70-1 LPAR numbers instead for headline CF util for Shared but not Dedicated.
- R744SETM records in-CF CPU for the structures. A 100% capture ratio does slightly weird things
- Check out a blog post on this topic
Mainframe – How to prepare for IBM z17
- z/OS support will be on V2.4 and higher. Reminder 2.4 supported with an extended service contract.
- Full exploitation requires z/OS 3.1 + fixes.
- As usual, there are three important SMP/E FIXCATs:
- Required: IBM.Device.Server.z17-9175.RequiredService
- Recommended: IBM.Device.Server.z17-9175.RecommendedService
- Exploitation: IBM.Device.Server.z17-9175.Exploitation
- Sysplex hardware co-existence requirements: z15, z16, z17
- Somple Exploitation highlights:
- BCPii & HMC Hardened Security: BCPii enhancements to support server-based auth with JSON web token. Allows not previously available operations including asynchronous notifications
- Workload-Level Sustainability & Power Consumption: Provided by fixes on z/OS 3.1 and higher
- Workload Classification Pricing: Can collect data which allows you to classify workloads to allow for a price differentiation
- CE-LR CL6 & ICA-SR 2.0: Note that CL6 can only connect to CL6, and CL6 is for IBM z17. z17 CL5 can also connect to CL5 on older machines. ICA-SR 2.0 can connect to older ICA-SR adapters.
- CFLevel 26 : Need to run CFSizer. Strongly recommend to use the z/OSMF CFSizer. There will be a PTF to add CFLEVEL 26 support to z/OSMF CFRM Policy Editor.
- System Recovery Boost: No new recovery boost types at this point.
- Data Processing Unit is the Integrated I/O Architecture.
- Network Express feature: New converged I/O card. Enhanced QDIO as well as RoCE.
- Crypto: Clear Key acceleration using a new CPACF instruction. No new cryptographic algorithms.
- z/OS handy support matrix for IBM z17:
Mainframe Also – z/OS 3.2
- z/OS 3.2 Preview timed to coincide with th April 8 IBM z17 announcement. Planned to GA September 2025, as usual.
- z/OS 3.2 can IPL on IBM z15 and higher.
- By the way, z15 is the first to do System Recovery Boost, so that means all z/OS 3.2 could use System Recovery Boost.
- Some of the previewed functions include:
- Support for the z17 hardware-accelerated AI capabilities.
- Python EzNoSQL APIs, extending EzNoSQL for this modern language.
- Communications Server is planned to use AI to provide intelligent network packet batching.
- PARMLIB syntax validator for selected members through a REST API, for example ALLOCxx. This is for syntax not semantics. You can validate multiple members possible in one run. Returns JSON of parsings, as well as OK / Not OK. Syntax error flagged with valid values.
- Automate software update installations via a new set of REST APIs added to the z/OSMF Software Update application. Also can be used by Ansible.
- z/OSMF has user interface for DFSMS Storage Management, including REST APIs.
- DFSMS support for direct encryption to tape.
- RACF certificate support for multiple altnames
- Of course, there will be more to come. Watch for a General Availability announcement.
Performance – IBM z17
- Discussion about chips:
- To understand Telum 2 you need to understand Telum.
- Telum basics: 8 PU cores, DCM, Shared Caches.
- Telum 2 as an evolution…
- 7nm to 5nm benefits most notably with real estate for DPU and bigger cache.
- Clock speed increase from 5.2 to 5.5GHz: energy consumption reduction.
- Data Processing Unit (DPU). 4-port cards vs 2-port offers space reduction, and energy consumption reduction. DPU is accessible from other chips and DCMs.
- IBM z Integrated Accelerator for AI (AIU): enhancements include INT8 and FP16. 8-bit integer, for example, datatype gets more throughput.Sharing within the drawer. Both these mean potentially more inferencing while meeting SLA’s.
- Non-chip discussion:
- Spyre: More aimed at Generative AI than AIU is. We’ll cover this topic more in another episode.
- 4 drawer models are Max183 and Max208. 1-drawer, 2, 3. 43 vs 39, 47 vs 43 CPs in a drawer. Max183 closer to Max208 than Max168 was to Max200.
- Maximum memory increased. 40TB -> 64TB. Per drawer might be more interesting.
- Instrumentation primer:
- Sustainability metrics in SMF 70-1, and other places.
- DPU in SMF 73 in general and for Channel Measurement Group 4 and 5.
- More on these topics at another time.
- Like every generation, there’s some nice new functions and handy capacity increases.
Topics – Preparing for z17
- Marna prepared for z17 by working on the z/OS z17 Upgrade Workflow and preparing customer presentations from that Workflow.
- Martin participated in Redbook writing.
- The team was composed of folks from around the world, including a couple of customers.
- This was Martin’s first processor Redbook, but of course not his first Redbook.
- The Redbook was written with individual chapters owned by individuals or subteams.
- The z17 Redbooks were based on z16 Redbooks, picking through what’s new painstakingly. Back in old days was written in Bookmaster, now Framemaker.
- The goal was to describe what z17 is rather than compare to z16 in Technical Guide, however, there is some need to compare and explain things like Branch Prediction.
- To some extent it was “Thriving On Chaos”, which is a callout to a famous book by Tom Peters, a management guru.
- Hot Chips conference was an early solid data point, as well as discussions with z/OS Development in Poughkeepsie in January 2025.
- Martin’s analysis code will need updating, and he’s looking forward to actual customer data and mappings, understanding how it behaves.
- We both are looking forward to talking about z17 in the future.
Out and about
- Martin is going to Istanbul twice in the next few weeks to visit customers,and also is doing the GS UK Virtual Conference 29 April – 1 May.
- Marna isn’t going anywhere until SHARE in August 18th – 22nd, Cleveland Ohio.
On the blog
- Martin’s recent blog posts:
- Marna’s recent blog posts:
Mainframe, Performance, Topics 