Starting in zOS 3.1, a basic or parallel sysplex requires a sysplex couple data set (CDS) that is formatted to support the System Status Detection (SSD) protocol. Over time, new function will depend on information that is stored in this CDS level and not available in earlier levels.
The SYSPLEX CDS needs to be formatted to include : ITEM NAME(SSTATDET) NUMBER(1) The steps to do so dynamically are in the link below, along with the changes required to IPL at 3.1 for the SYPLEX CDS. Once allocated, doing the ACOUPLE/PSWITCH commands ensure the data is in sync between the previous allocated CDS and the newly allocated one, and allows the use of the newly formatted ones. No IPL is required. See: https://www.ibm.com/docs/en/zos/3.1.0?topic=SSLTBW_3.1.0/com.ibm.zos.v3r1.e0zm100/Export_zOS_V2R4_to_V3R1_Upgrade_Workflow.htm#mark18 --Mickey Virdi -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Peter Sent: Tuesday, January 6, 2026 7:58 AM To: [email protected] Subject: [EXTERNAL] Re: Couple dataset format level Upgrading from 2.4 to 3.1 On Tue, 6 Jan 2026, 16:31 salva, <[email protected]> wrote: > I think you must allocate new and perform the PSWITCH procedue on the > origin sysplex. > > Witch z/OS versions are involved? > > > El mar, 6 ene 2026, 12:49, Peter < > [email protected]> escribió: > > > The error i got was while IPL where CDS were not usable due to > > version level. > > > > At that point I had to respond to COUPLE dataset prompt and does > > PSWITCH has ability of copying when the IXC255I message is issued ? > > > > > > > > On Tue, 6 Jan 2026, 15:44 salva, <[email protected]> wrote: > > > > > The SETXCF PSWITCH command does the magic! > > > > > > El mar, 6 ene 2026, 12:23, Peter < > > > [email protected]> escribió: > > > > > > > Hello > > > > > > > > So our couplexx member has XCFCDS , WLMCDS and LOGRCDS. > > > > > > > > > > > > I can allocate a new one and switch to the primary and alternate > > > > but > > how > > > do > > > > I make sure the older policies or definition of CDS are carry > forwarded > > > in > > > > the new CDS ? > > > > > > > > Peter > > > > > > > > On Tue, 6 Jan 2026, 15:06 salva, <[email protected]> wrote: > > > > > > > > > An IPL is not required. You can switch to a new CDS using > > > > > SETXCF > > COUPLE > > > > > command. > > > > > > > > > > > > > > > > > > > > > > > > > https://www.ibm.com/docs/en/zos/3.1.0?topic=ma-make-newly-formatted-co > uple-data-set-available-sysplex > > > > > > > > > > El mar, 6 ene 2026, 11:33, Peter < > > > > > [email protected]> escribió: > > > > > > > > > > > Is it same procedure for WLMCDS too ? > > > > > > > > > > > > On Tue, 6 Jan 2026, 14:09 Mike Schwab, < > > > > > > [email protected]> wrote: > > > > > > > > > > > > > To swap sysplex data sets, Define new datasets. Use > > > > > > > capacity > > tool > > > > for > > > > > > > sysplex data sets to determine needed size, or define as > > > > > > > twice > > the > > > > > > > actual current used amounts. Use new datasets with the > > > > > > > first > IPL > > > on > > > > > > > the new level, then have other IPLs on the new system join > > > > > > > the > > > > sysplex > > > > > > > using the new datasets. To fall back, IPL with old datasets. > > > > > > > > > > > > > > On Tue, Jan 6, 2026 at 12:53 AM Peter > > > > > > > <[email protected]> wrote: > > > > > > > > > > > > > > > > Hello > > > > > > > > > > > > > > > > During the upgrade of zos 3.1, I got this below mesaage > > > > > > > > as > . I > > > > > believe > > > > > > > the > > > > > > > > CDS was not formatted correctly to the level of zos 3.1 > > > > > > > > > > > > > > > > Ours is a monoplex. Is there a way to upgrade the > > > > > > > > current > > couple > > > > from > > > > > > > z/OS > > > > > > > > 2.4 to z/OS 3.1 > > > > > > > > > > > > > > > > IXC255I UNABLE TO USE DATA SET > > > > > > > > > > > > > > > > SYS1.XXXX.XCFCDS1 > > > > > > > > > > > > > > > > AS THE PRIMARY FOR SYSPLEX: > > > > > > > > > > > > > > > > > > > > > > > > IT WAS CREATED AT A FORMAT LEVEL LOWER THAN THIS SYSTEM > > REQUIRES > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Regards > > > > > > > > Peter > > > > > > > > > > > > > > > > > > > > > > > -------------------------------------------------------------------- > > -- > > > > > > > > For IBM-MAIN subscribe / signoff / archive access > instructions, > > > > > > > > send email to [email protected] with the message: > INFO > > > > > IBM-MAIN > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > Mike A Schwab, Springfield IL USA Where do Forest Rangers > > > > > > > go to get away from it all? > > > > > > > > > > > > > > > > > > > ---------------------------------------------------------------------- > > > > > > > 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 > > > > > > > > > > > > > > > > > > -------------------------------------------------------------------- > > -- > > > > > 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 > > > > > > > > > > ------------------------------------------------------------------ > > > ---- 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 > > > > ---------------------------------------------------------------------- > 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 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
