Appendix B: VM/370 MSS Support VM/370 MSS Support Following are annotated flow diagrams for the logic to support the IBM 3850 Mass Storage system. LOGON A USER BAVING A MINIDISK ON AN UNMOUNTED SYSTEM VOLUME A required system volume is not mounted, try to get a 3330V mounted
if the minidisk is a 3330. DMKSSSLN to mount an MSS system volume. DMKSSS, FINDRDEV real 3330V device. This may involve demounting a
volume which is mounted but not in use. If there are none such
volumes available, issue message DMKSSS080E and return with return
code 8. DMKSSS, ---Construct an MSSCOM, filling in the volume serial, device address
selected, type of request (mount), and userid. DMKSSS, SETMNTFG ---auIld-i-cPEIBLOK for the return to DMKLNK after the MSC has processed
the request. Chain it from field MSSTASK2. Build a CPEXBLOK for the
return to DMKLNK after the mount is complete (pack change
interruption received on the 3330V). Chain it fro. field MSSTASK1. DMKSSS, SCBMSSC ---Put the-ftSSCOM in the queue, generate an attention interruption for
the communication device if necessary. and exit to DMKDSP. BVCQ!!!% Entry when DIAGNOSE code X'18', subcode 4 is received. OS/VS is
ready to process an MSC request. Place the next 8SSCOM in the
virtual machine, and return to DMKBVC. DMKSSS, BVC08ENT -- Entry-froi--D8KBVC when DIAGNOSE code X'18', subcode 8 is received.
The MSC has processed the mount request. If there was an MSS error, write message DMKSSS083E and return to DMKLNK with return code 8. If there was not an MSS error, indicate
waiting for the pack change interruption.
Return to DMKLINK with return code 4. that the MSSC08 is now Write message D8KSSS088I. Return from DMKSSS. Save the current workarea and control
information. Return to caller.
Appendix B: VM/370 MSS Support 1-423
DMKDSB -- Entry from DMKDAS on pack change interruption. If the device is a 3330V, look for an MSSCOM waiting for this volume serial. If one is
found, stack a CPFIBLOK for entry to DMKSSSEN. Exit to DMKDSP. DMKSSSEN ---PIck-up -the CPEIBLOK for DMKLNKSS and stack it. DMKLNKSS ---complete the LINK processing for the minidisk. LOGON A USER HAVING A 3330V DEDICATED AS A 3330V Determine that a virtual 3330V is needed, save the UDEVBLOK, call DMKSSSL1. Go through device allocation, etc., to schedule a mount. DMKLOG, MSSMOUNT MS5-mount is in process (return code 4 from DMKSSS), proceed to
get the next directory statement. Otherwise, find the RDEVBLOK for
the device that DMKSSS allocated and continue the dedicat process. DMKLOGSS from DMKDSB and DMKSSSEN after .ount. Get the RDEVBLOK DMKVDSAT the virtual device. TST!JJJ! If the virtual device is a 3330V, set flag RDEV333V to indicate that
there is no CP MSS CCW prefix. If there is virtual I/O waiting, as indicated by a CPEXBLOK address
in field MSSTASK3 of the MSSCOM used for the mount, stack the IOBLOK. Return to DMKDSP. PROCESS DIAGNOSE CODE 1'78' Entry from DMKHVC when DIAGNOSE code is 1'78'. The entry subcode was O. Save the communication device address and
the communicator VMBLOK address. Set PSAMSS indicating that the Mse is now available.· The entry subcode was 4. If there is an MsseOM in the queue to be processed, call DMKPTRAN to get the communicator's buffer address.
Put the MsseOM in the virtual machine buffer.
1-424 IBM VM/370 System Logic and Problem Determination--Volume 1
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