For real reserve/release to be used for cross-system protection, the minidisks must be full-pack, not just start at cylinder 0, and SHARED must be on for the rdev.
Mike Harding EDS VM National Capability 134 El Portal Place Clayton, Ca. USA 94517-1742 * phone: +01-925-672-4403 * Fax: +01-925-672-4403 * mailto:[EMAIL PROTECTED] * <mailto:[EMAIL PROTECTED]> (personal) Note: For 2006, I am off on Fridays with even Julian dates and Mondays with odd ones. -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Rob van der Heij Sent: Wednesday, September 06, 2006 8:33 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: VM directory entry for shared DASD On 9/6/06, Wakser, David <[EMAIL PROTECTED]> wrote: > Please settle an argument: if a DASD volume is to be shared in > WRITE mode between two VSE systems running under VM, should the MDISK > statement specify MWV or MW? Why settle... can we not just disagree? ;-) If you have multiple systems on the same z/VM, you need MWV to make sure that CP will intercept reserve / release and emulate it. You could not have all virtual machines do real reserve release because the hardware would not be able to distinguish between virtual machines (only sees which LPAR does it). When the virtual machines are on different LPARs (or machines) you need the disk to start at cylinder 0 to ensure that CP will indeed pass the reserve/release to the real device (and I am not sure whether you have to define it as SHARED in the configuration file, but you prolly want to disable MDC anyway). When you more than one VSE in the z/VM LPAR and another one outside the LPAR (native or under z/VM, same machine or other machine) you need MWV *and* start at cyl 0 to make sure that CP will keep the guests apart, and will issue the real reserve/release that comes from that. Rob -- Rob van der Heij Velocity Software, Inc http://velocitysoftware.com/
