I have not specifically looked at what the general population have specified for RSU. But I do know that many systems out there have initial and reserved specified and have seen where some set rsu equal to their reserved, so some must be config'ing that offline for use by other lpars. Generally RSU=OFFLINE. I have also seen RSU=0 with reserved defined. Do the hardware guys have this information from active systems/lpar configurations out there? At least, how many have defined reserved central storage. One would think if they have reserved defined they would have a corresponding RSU to cover it.
________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of Jim Mulder <[email protected]> Sent: Wednesday, May 6, 2026 2:21 PM To: [email protected] <[email protected]> Subject: [EXTERNAL] Does anyone specify an RSU other than 0 in IEASYSxx? Does anyone still specify an RSU other than 0 in IEASYSxx, and use the CF STOR command to take storage offline from a z/OS system? The ability to deconfigure storage from a running MVS system was requirement on the old bipolar MP systems in order to dynamically reconfigure from single image to physically partitioned mode. The bipolar machines have been obsolete for decades, and the CMOS machines never had any concept of physical partitioning. CF STOR can be used on current machines to take storage offline from a running z/OS partition so that it can be reassigned to a different partition, presumably as a manual process for workload balancing reasons, But does anyone really do that? Specifying an RSU other than 0 to describe the amount of storage that can be dynamically taken offline requires that amount of storage to be set aside and not used for common storage fixed pages or long term fixed pages owned by nonswappable address spaces. Managing that separation is a complex process which can reduce system performance and reliability. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
