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z/VSE Parallel Access Volume White Paper                                                                                                                               12/08/2009 

©Andreas Vischer  

IBM Germany Development & Research GmbH 

 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
z/VSE Parallel Access Volume Support 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Vischer, Andreas 
z/VSE I/O Lead Developer 
vischer@de.ibm.com 
 
IBM Germany Research & Development GmbH 
Schoenaicherstr. 220 
71032 Boeblingen 
Germany 

Summary of Contents for ZVSE PARALLEL ACCESS

Page 1: ...2 08 2009 Andreas Vischer IBM Germany Development Research GmbH z VSE Parallel Access Volume Support Vischer Andreas z VSE I O Lead Developer vischer de ibm com IBM Germany Research Development GmbH Schoenaicherstr 220 71032 Boeblingen Germany ...

Page 2: ...and represent goals and objectives only References in this document to IBM products or services do not imply that IBM intends to make them available in every country The information could include technical inaccuracies or typographical errors Changes are periodically made to the information herein these changes will be incorporated in new editions of the publication IBM may make improvements and o...

Page 3: ...iases and their relationship in the storage unit hardware This unit address relationship creates a single logical volume allowing concurrent I O operations PAV can improve the performance of large volumes You can get better performance with one base and two aliases on a 3390 Model 9 than from three 3390 Model 3 volumes with no PAV support The storage unit supports concurrent or parallel data trans...

Page 4: ...Codes 51xx Base and alias devices defined in the System z IOCDS Base and alias devices are transparent to the IOCDS and therefore both fully qualified IODEVICE definitions in the IOCDS Base device defined in the z VSE IPL start up procedure corresponding ADD statement Starting of the z VSE PAV support via SYSDEF SYSTEM PAV START command see following section For more information examples and a mor...

Page 5: ...ASE 777 ESTABLISHED AR 0028 1K01I ALIAS DEVICE 77E FOR BASE 777 ESTABLISHED AR 0028 1K01I ALIAS DEVICE 779 FOR BASE 777 ESTABLISHED AR 0028 1K01I ALIAS DEVICE 77A FOR BASE 777 ESTABLISHED AR 0028 1K01I ALIAS DEVICE 77B FOR BASE 777 ESTABLISHED AR 0015 1I40I READY AR 0015 1I40I READY sysdef system pav Stop sysdef system pav Stop sysdef system pav Stop sysdef system pav Stop AR 0015 1I40I READY QUER...

Page 6: ...sir smf vse 261 AR 0015 TIMINGS FOR 261 BASED ON 589 I O INSTRUCTION AR 0015 MAXIMUM I O QUEUE2 2 2 2 3 AR 0015 AR 0015 QUEUED PENDING CONNECT DISCONN DEV BUSY TOTAL AR 0015 msec SSCH msec SSCH msec SSCH msec SSCH msec SSCH msec SSCH AR 0015 0 000 0 000 0 369 0 000 0 000 0 369 AR 0015 1I40I READY For PAV base devices the SIR SMF VSE cuu output will display I O counts for the associated aliases The...

Page 7: ...0 UNUSED 10017 CYL A new DETAIL option has been implemented to display possible alias devices related to the base AR 0015 1I40I READY volume 777 detail AR 0015 CUU CODE DEV TYP VOLID USAGE SHARED STATUS CAPACITY AR 0015 777 6E B 2105 000 FRA740 UNUSED 10017 CYL AR 0015 BASE TO 778 77E 779 77A 77B BASE TO 778 77E 779 77A 77B BASE TO 778 77E 779 77A 77B BASE TO 778 77E 779 77A 77B AR 0015 1I40I READ...

Page 8: ...ing for parallel I O s by selecting a free device among the available base and alias devices To help identifying devices that are candidates to improve performance by using PAV the output of the SIR SMF VSE cuu command can be used Example sir smf vse 261 AR 0015 MAXIMUM I O QUEUE 3 MAXIMUM I O QUEUE 3 MAXIMUM I O QUEUE 3 MAXIMUM I O QUEUE 3 In this case a maximum of 3 I O requests were queued to t...

Page 9: ...configuration ALIAS recognition A dynamic add of alias devices is not supported Thus devices becoming active are just ignored However if a base device becomes ready while having PAV support active all corresponding aliases will be activated too Alias devices becoming not operational are taken out of PAV processing As indication the alias cuu is put in brackets on the VOLUME cuu DETAIL output Even ...

Page 10: ...PAV support enabled and having z VM Mdisks allocated on these volumes controlled by z VM do not support basic PAV emulation over Hyper PAV and vice versa aliases attached to z VSE while Hyper PAV is active on the corresponding control unit are not recognized during z VSE PAV activation Commands relevant for z VM PAV guest support o QUERY PAV o QUERY VIRTUAL PAV o QUERY CU o SET CU For further info...

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