René Ferland wrote:
/attach 481 to cmsuser as 181
devinit 481 jim.het
tape dump * * a
devinit 481 *
/detach 481 from cmsuser
and it generates no error messages.
Because you asked VM *directly* to detach REAL device X'481' drive from its CMS guest's system, I'm guessing it didn't bother trying to unload whatever media it might have thought might still be mounted on the drive. It didn't issue the "run" CCW (X'0F' = "Rewind and Unload"), but rather instead decided to leave the tape drive alone. It decided to leave the media (the tape) mounted on the drive, position right where it was at.
In Jim's scenario however, he detached the virtual drive from his CMS userid, which triggered VM to issue the "run" CCW to the corresponding real device to unload the media (the tape) that it *believed* was still mounted there. I believe VM is purposely coded that way. Under some conditions it doesn't unload the tape from the drive whereas under other conditions it does. I can't remember. It's been too many years.
On DOS/VS, I use a similar sequence:
/attach 481 to dosvs as 280
(submit my job)
devinit 481 jim.het
devinit 481 *
/detach 481 from dosvs
Which is the same exact thing since your "dosvs" was, like "cmsuser", just another virtual machine GUEST running under the VM hypervisor, which is the REAL operating system in this situation, and the one that is ultimately in control of its own REAL devices.
[...]
Moreover, on DOS/VS, if I am to work with tapes, I will
typically do the /attach before the IPL, once for all,
and the /detach after the shutdown.
Which IMO is the correct way to do it.
If I run DOS/VS native, the attach/detach is not needed because
the tapes are already defined in my Hercules configuration file.
Precisely.
--
"Fish" (David B. Trout)
Software Development Laboratories
mail: fish@...
