On Tue, Jan 16, 2024 at 15:05 Bob Polmanter <wably@...> wrote:
The hardest part of this is having a second VM system that you can use that does not have the same volume names as your first level system.
Note that there are several kinds of disks in a VM system. ?"Dedicated" disks are ATTACHed to a virtual machine when it logs on, and are usually identified by their real (to CP) device address.? Other disks are usually ATTACHed to SYSTEM (meaning CP), and are used for either virtual disks or system functions.? The vdisks, page areas, SPOOL data, etc. are all bound to a disk by its volser.? You cannot have two disks with the same volser attached to CP at the same time.
The disks you absolutely cannot share are those CP uses itself - paging, SPOOL, etc.? Those are all identified by volser in DMKSYS.? You can share disks that aren't on that list, but you shouldn't let both systems have them R/W.? A CMS filesystem can easily be damaged if two systems (or even two CMS users on the same system) have it online and accessed R/W.
