A SENSE command is not dangerous. Its response comes from the Control Unit and only reports status without altering it. If there is no device at the address, a cc=3 is returned by the VM CP based on the lack of a VDEV.
About the only window for mischief, and it is just hypothetical, would be if you could issue the SENSE between the time that a Unit Check is presented by the hardware to CP and CP's doing a SENSE to get the status. Like I say, hypothetical because I doubt that there really is even that teeny-tiny window - if there is a unit check, CP will undoubtedly do a SENSE before it presents the UC to the VM starts the next virtual machine I/O. If the VIO is a SENSE, the saved status is returned; if not, the status is cleared just as it would be in the real hardware. Regards, Richard Schuh > -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Imler, Steven J > Sent: Wednesday, January 23, 2008 10:07 AM > To: [email protected] > Subject: Re: how to wait for dfsmsrm command > > But isn't that a bit dangerous ... for the requestor to be > issuing tape commands and/or CCWs to the attached tape drive > while RMSMASTR is "doing its thing" mounting the tape for the > requestor? > > JR (Steven) Imler > CA > Senior Software Engineer > Tel: +1 703 708 3479 > Fax: +1 703 708 3267 > [EMAIL PROTECTED] > > > > -----Original Message----- > > From: The IBM z/VM Operating System > > [mailto:[EMAIL PROTECTED] On Behalf Of Les Geer > (607-429-3580) > > Sent: Wednesday, January 23, 2008 12:50 PM > > To: [email protected] > > Subject: Re: how to wait for dfsmsrm command > > > > > } The only problem with using a tool like this is that while > > > DFSMS/VM is } mounting the tape for you, the tape drive > is attached > > > to the RMSMASTR } virtual machine, not the requestor's virtual > > > machine. The tape drive is } not attached to the requestor until > > > the requested tape is loaded and the } drive is ready ... > > > > Or first attach the drive to the requester's machine using the > > multiuser option before issuing the mount request. > > > > > > Best Regards, > > Les Geer > > > > >
