3850 MSS When a/virtual machine is given access to the MSS, one interface to
the MSC is dedicated to that virtual machine. To the MSC, this is the
same as having that interface connected to a native processor. Thus,
the MSC tables must be constructed so that the MSC can process requests
from the virtual machine. The MSC must treat the requests as if they
came from a native processor, controlling the other components of the MSS such that MSS activity, as seen by VM/370 and the virtual machines,
occurs on the correct 3330V device address.
Consider the example of a virtual machine that is given a virtual CPUID of 12345. This processor also has one of dedicatecf to - it Su ppose-- that- VPI/370' S 3330V 250 is dedicated to the
virtual machine as virtual device address 150. When virtual CPUID 12345
issues an order to the MSC, the 3330V placed in the order will be 150. When interruptions are generated for this 3330V they will be sent from
the Staging Adapter on the interface that corresponds to virtual CPUID 12345's 150. Since that device is known by VM/370 as 250, the MSC tables must have been constructed such that the definition of 3330V 150 for virtual CPUID 12345 corresponds to the physical connection known to VM/370 as 250.
Each 3330V in the MSC tables must map to a specific channel
attachment on a specific Staging Adapter. In this case, the MSC table
was constructed so that the definition for 3330V 150 on virtual CPUID 12345 corresponds to the physical connection from the real processor.
This connection is through channel 2 to the same upper interface on the Staging Adapter. Thus, interruptions received from the virtual
machine's 150 are received on VM/370's 250 as long as it is dedicated to
the virtual machine corresponding to virtual CPUID 12345. Similarly,
when the virtual machine issues an MSC order such as demount, the volume
on VM/370's 250 is the volume demounted.
Two different virtual machines, having
addresses can run concurrently under VM/370. machines, each of which has defined a 3330V device address 150, then the MSC tables
configuration can be set so that each virtual
at address 150. the same virtual device
If there are two virtual
at the virtual machine's
and the physical MSS machine can have a 3330V One configuration has a native processor with two block multiplexor
channels, channel 1 and 2, and one Staging Adapter. Channel 1 is
connected to the B interface of the Staging Adapter and channel 2 is
connected to the C interface of the Staging Adapter. The VM/370 system
has 3330Vs generated as 140 through 17F and 240 through 27F. Two
virtual machines are defined as CPUID 11111 and CPUID 22222. Each of
these machines can support an operating system in which the 3330Vs are
generated at addresses 140 through 17F. The MSC tables for this
configuration m-ust show CPUID 11111 with its 3330Vs 140-17F mapped to
the Staging Adapter interface Band CPUID 22222 with its 3330Vs 140-17F
mapped to the Staging Adapter interface C.
CREATING MSS VOLUMES Before a pair of MSS data cartridges can be treated as a volume or
accessed as VM/370 system volumes, they must be initialized as the image
of a disk packe This initialization is accomplished by the use of
an OS/VS access method services command called CREATEV. CREATEV is one
of several commands that are part of the MSS component of the access
method services, which in turn is a standard component of OS/VS1 and OS/VS2. CREATEV can run either under VS running on a native processor, Part 1. Planning for System Generation 75

3A50 MSS or VS running in a virtual machine to which an MSC port has been
dedicated. In either case, once CREATEV has completed, the volume is
known to the MSS and may be referenced in MSC mount and demount orders. COPYING 3330-1 VOLUMES TO 3330V VOLUMES A full or partial 3330-1 volume may be copied to 3330V volumes. Once the MSS volumes have been initialized as described previously, with CREATEV, either of the following may be done: • The access method services command CONVERTV may be executed from
either a native processor or a VS virtual machine. This will make a
bit by bit copy of the 3330-1 on the MSS 3330V. • Allor part of the 3330-1 volume and the 3330V volume can be
allocated to a virtual machine using the directory MDISK or DEDICATE
statements or the operator ATTACH command. Standard CMS. OS. DOS. OS/VS and stand-alone utilities can then be used to copy data to the MSS volume. USING 3330V VOLUMES FOR VS SYSTEM RESIDENCE A VS system can be loaded in a virtual machine from a 3330V volume because VM/310 can make the virtual IPL device appear to be a 3330-1. The following steps describe one way this can be done: • Use the CREATEV command to create an MSS volume with a volume serial
number of VOL001. • Define a directory entry for a virtual machine (VS2VK) with an KDISK statement, describing a minidisk spanning cylinders 1 through 401 on
volume VOL001. • VM/310 mounts VOLOOl and allocates the minidisk when VS2VK logs on.
The operator can then attach a 3330-1 containing a VS2 system to VS2VM. • Copy cylinders 0-400 of the 3330-1 to the minidisk within VS2VK. • IPL the virtual device address corresponding to the minidisk as a VS2 system residence device.
THE VM/310 RDEVICE MACRO The 3330V device addresses generated in the VM/310 control program can
be used for two purposes: they can have 3330V system volumes containing
minidisks mounted on them, or they can be dedicated to a virtual
machine. In either case, the control program can dynamically select a
specific device to satisfy a request. You must divide the pool of
available 3330V devices into two types, one for system volumes and one
for dedicated volumes. The FEATURE= operand of the RDEVICE macro is used
to first indicate that a device address is a 3330V as opposed to a 3330-1, and second, to indicate the type of 3330V system or
dedicated.
76 IBM VM/310 Planning and System Generation Guide