One caution on subcapacity and DDF: GCP threads will probably run slower than zIIP threads. SMT-2 might help reduce this variability - at the expense of slower threads on zIIP.
(This is not a recommendation - as it's rather more complex than that - but an observation.) Cheers, Martin From: IBM Mainframe Discussion List <[email protected]> on behalf of John S. Giltner, Jr. <[email protected]> Date: Monday, 15 June 2026 at 13:09 To: [email protected] <[email protected]> Subject: [EXTERNAL] Re: Selecting z model MSU How much zIIP workload do you have? You could go to a "smaller" machine if you have quite a bit of zIIP workload. We went from a z14-706 to a z15-608 both having 4 zIIP's. We have a significant amount of Db2 DDF work. So going from "fewer faster" to "more slower" GCP's and having faster zIIP's our CPU utilization, both GCP and zIIP went down. DDF work that was running on GCP's because we did not have enough zIIP could no go to zIIP's thus reducing work on GCP's. Since the zIIP's were faster, that work was completing in less time. Using zPCR is the way to go as that should help identify what will work for you and your workload. -- ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN Unless otherwise stated above: IBM United Kingdom Limited Registered in England and Wales with number 741598 Registered office: Building C, IBM Hursley Office, Hursley Park Road, Winchester, Hampshire SO21 2JN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
