Larry, Take a step back and consider that CP provides virtualization of hardware. When you logon to VM, CP builds a virtual machine as described at that moment in the "object directory" which was written by the 'DIRECTXA' command from the contents of the "USER DIRECT" file. That VM userid - again, a Virtual Machine, has CP commands to match almost every button, knob, and blinking light that exists on a real mainframe (think back to the good old 360's and 370's).
I found when first working on VM to think of CP as providing access to hardware -- things I could kick. Why the operating system IPLed (often automatically for me) when I logon a virtual machine userid provides programming languages, access methods, and file systems. When you issue 'CP VARY ON rdev' for a DASD device, CP sees it was "plugged in" for use. Remember that CP is a hypervisor and can't presume that all hardware is for it's own use. You might want to 'CP ATTACH rdev mvsguest' so that such an MVS guest can completely manage that DASD, with no sharing by any other VM users. ATTACHing a device to a user is also referred to as "DEDICATE" in the "USER DIRECT" file -- ATTACH is just the dynamic command to correspond to the directory "DEDICATE" statement. Or... you might have that DASD broken up into MDISKs (in "USER DIRECT") to be shared by many virtual machine userids at once. For that DASD to be shared by many users, CP needs to manage the DASD, hence the 'CP ATTACH rdev SYSTEM'. Now CP manages access to the various MDISKs on the device rather than letting a single user manage the whole thing. It may help to review "Chapter 6. Managing Your Virtual Machine I/O and Storage Devices" in "z/VM Virtual Machine Operation" (SC24-6128). You might also want to consider attending SHARE, where there are some pretty good "basics" sessions that help to explain this in more detail - and lots of people willing to spend time explaining things interactively (even over a malted beverage of your choice). Mike Walter Hewitt Associates The opinions expressed herein are mine alone, not my employer's. "Larry Macioce" <[EMAIL PROTECTED]> Sent by: "VM/ESA and z/VM Discussions" <[email protected]> 02/22/2006 02:09 PM Please respond to "VM/ESA and z/VM Discussions" <[email protected]> To [email protected] cc Subject Re: another question adding allocating dasd OK I did a q names and it shows: L2DRW01 - DSC Doesn't this mean the user is on and disconnected? In reading Davids answer it looks as if I need to log the instance off an d on. If I do a xautolog won't that take the the instance down? And if I do an autolog won't it show the instance already logged on? My other instances show -dsc also but still show the link. OH brother am I confused. thanks Mace The information contained in this e-mail and any accompanying documents may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient of this message, or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message, including any attachments. Any dissemination, distribution or other use of the contents of this message by anyone other than the intended recipient is strictly prohibited.
