The most current recommendation I've seen comes from Health Checker. At z/OS 1.9, an 'OK' result gives the message below. I would not venture to guess whether fast DASD and channels would allow you stray from the blessed path.
IXCH0243I For each couple dataset type the primary and alternate reside on different volumes this is consistent with the IBM recommendation. IXCH0241I The following PRIMARY couple datasets reside on unique volumes: SYS1.COUPLE.SYSPLEX1 SYS1.COUPLE.CFRM1 SYS1.COUPLE.LOGGER1 This is consistent with the IBM recommendation that the primary SYSPLEX couple dataset, the primary CFRM couple dataset, and the primary LOGR couple dataset, should be placed on different volumes. . . JO.Skip Robinson Southern California Edison Company Electric Dragon Team Paddler SHARE MVS Program Co-Manager 626-302-7535 Office 323-715-0595 Mobile [EMAIL PROTECTED] Lizette Koehler <[EMAIL PROTECTED] ING.COM> To Sent by: IBM IBM-MAIN@BAMA.UA.EDU Mainframe cc Discussion List <[EMAIL PROTECTED] Subject .EDU> Placement of Couple Data sets 10/19/2007 02:57 PM Please respond to IBM Mainframe Discussion List <[EMAIL PROTECTED] .EDU> The last manual I read on this was from 1999 Parallel Sysplex Performance Healthcheck Case Study: DMdata/Danske Data http://www.redbooks.ibm.com/redbooks/pdfs/sg245373.pdf I was wondering if this case study was still valid or if with the faster CPUs and ICF and DASD whether or not I need to revisit the placement of the CFRM, ARM, SFM, LOGR, SYSPLEX and OMVS Couple Data sets? I would like to know if all primaries on one volume and all alternates on a secondary would be valid now. And if with hardware like EMC Symmectrix and IBM 2105's with a source string and target string, whether or not placement is all that big of a deal? Lizette ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html