3850 PISS W.hen coding the RDEVICE macro for a 3330V device address, either FEATURE=VIRTUAL or FEATURE=SYSVIRT must be coded, where: VIRTUAL defines a 3330V that may not be used for system volumes. It
may be dedicated or attached to virtual machines as a 3330-1 or 3330V. SYSVIRT defines a 3330V that is used for VPI/370 system volumes. It
cannot be dedicated or attached to a virtual machine. PISS volumes
that are 3330V, can be mounted on SYSVIRT 3330V devices but cannot be
dedicated to a virtual machine by address, nor attached to other than
the system. -
To specify an alternate control unit on the RDEVICE macro, code: RDEVICE ADDRESS=cuu,DEVTYPE=nnnn,MODEL=n,ALTCU=cuu Figure 12 shows how the real I/O control block structure is coded and
logically appears when an alternate control unit is specified. RDEVICE RCTLUNIT ADDRESS=340,CUTYPE=3830,FEATURE=32-DEVICE RCTLUNIT ADDRESS=250,CUTYPE=3830,FEATURE=32-DEVICE RCU340 RCU350 RCU250 RCU348 RCU358 RCU258 r-> I I r->r r->. 1 r->. I- I I I I I I I I I I RCU260 RCU268 I 1 I I I<-I-IRCUSUBI I I 1< I-IRCUSUBI , I I I I , I I I I I I I I , I , I --I i I I , I I I I I RDV340-34F I I RDV350-35F I , I I I I I I I I , I L_I I I L-IRCU340 RDEVCUA I IRCU350lRDEVCUA I I ---I I I I IRCU250 RDEVCUB RDEVCUBIRCU2601 --I I I I I I I Figure 12. Real I/O Control Block Structure for Alternate Control Unit Specification Part 1. Planning for System Generation 77
3850 MSS To specify alternate channel addresses on the RCTLUNIT macro, code: RCTLUNIT ADDRESS=cuu,CUTYPE=nnnn,FEATURE=xxx-DEVICE, ALTCH= (1,2,4)
Figure 13 shows how the real I/O control block structure would be coded
and logically appear when alternate channels are specified. Note that
the subordinate control unit blocks do not contain pointers to the
alternate channel blocks. Only the prime control unit block contains
pointers to the alternate RCHBLOKS. This is consistent with the current CP block structure. RCTLUNIT ADDRESS=340,CUTYPE=3830,FEATURE=32-DEVICE,ALTCH=(1,2,4) RCHANNEL ADDRESS=1,CHTYPE=MULTIPLEXOR RCHANNEL ADDRESS=2,CHTYPE=MULTIPLEXOR RCHANNEL ADDRESS=3,CHTYPE=MULTIPLEXOR RCHANNEL ADDRESS=4,CHTYPE=MULTIPLEXOR RCHAN1 RCHAN2 RCHAN3 RCHAN4 r->.- r->. r->. r->. I 1 I I I 1 I , L 1 L- , I I I RCU340 RCU350 I RCU348 RCU358 I i , , I I I I ----.I IRCUSUB 1 , 1 RCHAN3 RCUCHA I I I I I 1 L +-1 RCHAN1 RCUCHB IRCU340 I I I 1---1 L--IRCHAN2 RCUCHC I 1 1 1 I I RCHAN4 RCUCHD 1 I L ----, 1 L
Figure 13. Real I/O Control Block Structure for Alternate Channel
Specification
The following restrictions apply directly to Alternate Path processing: VM/370 does not support alternate paths for devices
attention interrupts to invoke a read response from the
example, the 3851 Mass storage Control (MSC) unit.
that issue
host; for All devices on one physical control unit must be defined as either
alternate path or no alternate path. There can be no splitting of
control units when dealing with alternate paths. 78 IBM VM/370 Planning and System Generation Guide
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