Z/OS Basics: Virtual Storage Management (VSM) Overview

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IBM Systems & Technolgy Groupz/OS Basics: Virtual StorageManagement (VSM) OverviewElpida Tzortzatos – email: elpida@us.ibm.com1 2009 IBM Corporation

Agendaz/OS Memory/Storage Types z/OS Memory Managers 31-Bit VSM Basics Recent Enhancements 64-BitVSM/RSMBasics Recent Enhancements Appendices CSA Common Storage Tracker2

z/OS Memory/Storage Types3

z/OS Memory Types Memory management viewsPageDatasetsReal storageframes (physicalCPU memory)Virtual pages inmultiple address spaces(created through DAT)Auxiliary slots on(DASD) volumes(paging datasets)4

z/OS Memory Controls Real Virtual Mixture of z/OS internal thresholds and system-wideparametersCustomer-specified policies via JCL, SystemManagement Facility (SMF) parameters and exitsGenerally either prevent work exceeding the limitsfrom starting or causes work to terminate if itexceeds a limit during executionProcess-level granularityAux z/OS internal thresholds coupled with paging datasetconfiguration: number of datasets, size of each5

Storage Types (all with respect to z/OS’s point of view) Virtual memory/storage DATDAT-on addressingExplicitly allocated either by the system or applications24, 31, or 64 bit residency mode (rmode(rmode))3131-bit virtual is allocated/freed in multiple of 8 byte chunks6464-bit virtual is allocated in 1MB multiples on a 1M boundaryVirtual storage attributes are specified when virtual storage is allocated Real memory/storage Based on addressing mode of application and whether or not the “real view”view” will be usedExample: the ordinary 3131-bit application requires 3131-bit virtual pages but the frame backingeach page may have a 6464-bit real addressExpanded storage DATDAT-off addressing, Real Space ALET, I/O, some privileged opop-codes specify real addresses4 KB page frames (often: just “frames”frames”), 1MB page frames (often just “large pages”pages”)24, 31, or 64 bit residency mode (rmode(rmode))Each memory allocation request to z/OS specifies allowable virtual and real rmodes Fixed (pinned), DREF, pageable,pageable, 1MB pagesWhen physical resources (real memory/paging space) are assigned to virtual storage depends on thevirtual storage attributesNo longer used by z/OSMidMid-1980s to early 2000s, electronic storage with characteristics betweenbetween real and auxiliaryin terms of response time and monetary costFunctioned mostly as a fast synchronous paging deviceAuxiliary (storage, on Disk/DASD) Used for paging and swapping4 KB slots in one or more paging datasetsInvisible to applications6

Virtual/Real MapTheoretical Max 16 EB (2**64)64 bitaddressable4 TBCurrent maximumreal storagesupported by z/OS“The Bar” 2 GB“The Line” 16 MB31 bit addressable24 bit addressableLow memory address: 07

z/OS Memory Managers8

z/OS Memory Managers: VSMVirtual Storage ManagerAddress Space-centric view of the system andprocessesObjectives 1.2.Control the allocation/deallocation of 31/64-bit virtual storageaddressesObey policies imposed on it by customer specified limits1.3. Each installation can use virtual storage parameters (inSys1.Parmlib,JCL, SMF) to specify how certain virtual storageareas are to be allocated to programsEfficiency – minimum overhead per requestAssociate a storage protection key with each virtualstorage block requestedMaintain storage use information by generating SMFrecords.9

z/OS Memory Managers: RSMReal Storage ManagerFrame-centric view of the system and processesObjectives 1.2.3.4.Keep the system upObey policies imposed on it by the customer, SRMEfficiency – minimum overhead per requestManage 64-bit storage requestsResource pools Expanded frames (historical only)Real storage frames Individual framesFrame pairs: 2 contiguous in real on particular boundaryQuad frames: 4 contiguous in real on particular boundaryMajor policy knobs that control its behavior Optional per-process minimum/maximum number of frames Processes below minimum stolen from last, above maximum firstSystem-wide thresholds controlling paging Begin stealing when less than X frames unallocated, steal until Y frames available10

Dynamic Address Translation V ir t u a l A d d r e s s S p a c e seSzASCEA S C E .6 0 -6 11 1 - R e g io n 1 s t ta b le1 0 - R e g io n 2 n d t a b le0 1 - R e g io n 3 r d t a b le0 0 - S e g m e n t t a b leP a g e Ta b leerisD a ta P a g eSegm entTa b leR e g io n 3 r dTa b leR e g io n 2 n dTa b leE ffe c tiv e V ir tu a l A d d r e s sR e g io n 1 s tTa b le11RFX111111812RSXRTXSXPXBXT r a n s la tio n c a n s ta r t a t R 1 T , R 2 T , R 3 T o r S G TT h e s ta r tin g p o in t o f th e tr a n s la tio n is d e s ig n a te d inth e A d d r e s s S p a c e C o n tr o l E le m e n t ( A S C E .6 0 - 6 1 )C o p y r ig h t IB M C o r p o r a tio n 2 0 0 0 , 2 0 0 111

Large (1MB) Page DATArchitectureASCEASCE.60-6111 - Region 1st table10 - Region 2nd table01 - Region 3rd table00 - Segment tableLarge Data PageSegmentTableRegion 2ndTableRegion 1stTable.Region 3rdTableEffective Virtual Address11RFX11RSX11RTX11SX20BXTranslation can start at R1T, R2T, R3T or SGTThe starting point of the translation is designated inthe Address Space Control Element (ASCE.60-61)12

z/OS Memory Managers: ASMAuxiliary Storage ManagerPaging-centric view of the system; virtually no process awarenessObjectives 1.Efficiency – minimum overhead per request Highly optimized Slot allocation efficiency falls dramatically once utilization ofof a dataset rises above 30%ASM tries to equalize the number of slots allocated across the datasets,datasets, not their % allocatedRelies on other managers to only give it sensible requestsAn auxiliary storage slot is allocated to a page when the page isis paged outAn aux slot is freed when the page is freed or reused when the pagepage is paged outagainPeriodically RSM calls ASM to free slots for pages that are changedchanged in real storageResource pools 1-n Paging datasets formatted into 4 KB slots Called paging datasets, but used for both paged out and physicallyphysically swapped framesMajor policy knobs that control its behavior Number of paging datasets and size of each Datasets may be different sizes13

31-Bit VSM14

Virtual memory/storage DAT-on addressingExplicitly allocated either by the system or applications24, 31, or 64 bit residency mode (rmode)31-bit virtual is allocated/freed in multiple of 8 byte chunks64-bit virtual is allocated in 1MB multiples on a 1M boundaryVirtual storage attributes are specified when virtual storage isallocated Fixed (pinned), DREF, pageable, 1MB pagesWhen physical resources (real memory/paging space) are assignedto virtual storage depends on the virtual storage attributes15

31-Bit Address Space Memory Map2 Gig 80000000Extended Private16 Meg 1000000Extended CSAExtended LPAExtended SQAExtended NucleusNucleusSQALPACSAPrivate600020000System RegionPSAGlobal storage includes Nucleus,Extended Nucleus, SQA, ESQA,LPA, ELPA, CSA, and ECSAGlobal storage managed by VSMincludes SQA, ESQA, CSA, andECSAUpper boundary of ECSA storageand lower boundary of CSAstorage are always on aMegabyte boundarySizes of SQA, ESQA, CSA, andECSA storage are specified at IPLtime via the IEASYSxx parmlibmember16

Local Storage AreaLSQA / SWA / high pvtUser regionAuthorized storage (LSQA, SWA, and highprivate) is assigned from the high end of the localstorage box. In other words, this storage growsfrom the top of the box down.Unauthorized storage (user region) isassigned from the low end of the localstorage box. It grows from the bottom of thebox up.17

z/OS Memory Managers: VSMV S M S to ra g e M a n a g e m e n t R u le sM V S m a n a g e s s to ra g e th ro u g h th e u s e o f s u b p o o lsd e s ig n e d to a c c o m m o d a te a v a rie ty o f s to ra g e n e e d sS to ra g e is a llo c a te d o r a s s ig n e d to a s u b p o o l in o n ep a g e (4 K ) m u ltip le sS to ra g e b e lo n g in g to d iffe re n t s u b p o o ls c a n n o t o c c u p yth e s a m e p a g eS to ra g e w ith d iffe re n t s to ra g e k e y s c a n n o t o c c u p y th esam e pageS to ra g e b e lo n g in g to d iffe re n t T C B s c a n n o t o c c u p y th esam e page18

z/OS Memory Managers: VSMV S M S to ra g e M a n a g e m e n t R u le sW h e n th e re is n o t e n o u g h s to ra g e a b o v e th e lin e tofu lfill a n a b o v e th e lin e s to ra g e re q u e s t, V S M w illa tte m p t to h o n o r th e re q u e s t fro m b e lo w th e lin ein s te a dL S Q A / S W A / h ig h p riv a te p a g e s m a y n o t in te rm ixw ith u s e r re g io n p a g e sU n le s s o th e rw is e d ire c te d o n th e G E T M A INre q u e s t, V S M w ill g iv e o u t s to ra g e a t th e h ig h e n do f th e p a g e firs t19

z/OS Memory Managers: VSMP riv a te S u b p o o l A ttrib u te sS u b p o o l n u m b e rs 0 - 2 5 5S to r a g e p ro te c tio n K e y s 0 - 1 5U s e r R e g io n s u b p o o ls0 - 132, 250 - 252T C B -re la te dK e y e d s to ra g eU n a u th o riz e dG e n e ra l p u rp o s e s u b p o o ls* S e e M V S D ia g n o s is : R e fe r e n c e , C h a p te r 8 ,fo r a d d itio n a l s u b p o o l in fo r m a tio n .H ig h P riv a te s u b p o o ls229, 230, 249T C B -re la te dK e y e d s to ra g eA u th o riz e dS p e c ia l a u th o riz e da p p lic a tio n s to ra g eneedsLSQA2 5 5 (m a in ly )F ix e d , k e y 0 s to ra g eA d d re s s s p a c e -re la te d ,n o t T C B -re la te d20

Virtual Storage Allocation GETMAIN, STORAGE OBTAIN, or CPOOL macro requiredfor virtual storage allocation.GETMAIN will get storage from subpool 0STORAGE OBTAIN obtains storage in the primaryaddress space (by default) or in the address spacedefined through the ALET parameterNOTE: Compared to GETMAIN, STORAGE OBTAINprovides an easier-to-use interface and has fewerrestrictions. For programs running in AR mode or crossmemory mode use the STORAGE OBTAIN macro toobtain storage.Cellpool (carve storage as wanted after doing an initialGETMAIN - specify size of storage needed at each time)21

GETMAIN and STORAGE OBTAINUsing LOC Option LOC parameter on GETMAIN macro and/or STORAGE OBTAINindicates location of requested virtual storage and real storage whenthe page is fixed.Allows storage to be acquired anywhere in the 2 gigabyte addressrange.Caller can be in 24, 31, or 64 bit AMODEAll values and addresses are treated as 31-bit values and addresses.Specifying LOC(xx,64) indicates that central storage (real) can belocated anywhere in 64-bit storage.The LOC parameter is only valid for the following GETMAIN options RU - Register, Unconditional (get storage, if not available, ABEND)RC - Register, Conditional (get storage, return code, won't ABEND)VRU - Variable, Unconditional (between 200 and 500 bytes long, will tryto give 500 at worst, give 200, if not 200 ABEND)VRC - Variable, Conditional (if not minimum, get return code)22

Returning Virtual Storage STORAGE RELEASE releases storage in theprimary address space (by default) or in theaddress space defined through the ALETparameterFREEMAIN options Register, UnconditionalRegister, ConditionalTo free storage above the 16 MB line the RU/RCoptions of the FREEMAIN macro must be used.23

Obtaining Storage via CPOOL The CPOOL macro provides faster storage managementthan GETMAIN macroThe following services are available: Create a Cell Pool (Build) Obtain a Cell from an existing pool ?CPOOL (GET) UNCOND . . . ;Return a Cell to a Cell pool ?CPOOL (GET) COND . . . ;Extend a Cell pool, if necessary ?CPOOL (BUILD) . . . ;?CPOOL (FREE) . . . ;Free an entire Cell Pool ?CPOOL (DELETE) . . . ;24

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 Problem:– A large number of datasets are opened in theDB2 address space. This causes VSAM to do alot of GETMAINs/STORAGE OBTAINs** insubpool 252. This creates a long chain of DQEs for subpool 252 inthe DB2 address space. Long DQE chains causeperformance problems** Subsequent references to GETMAIN also apply to STORAGEOBTAIN25 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 Solution– Allocate virtual storage described by DQEs forlow private from the bottom of the page up,instead of from the top of the page down– This change in VSM allocation processing allowsfor a new allocation request to be merged into anexisting DQE since the address range iscontiguous; only the DQE size has to change26 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 Implementation Details (via DIAGxx)With APAR OA27291 / PTF UA45583 installed:– To enable this new behavior, code the following in theactive DIAGxx member:– VSM UsezOSV1R9Rules(No)– To revert back to the old algorithm of allocating virtualstorage in low private subpools, use “set diag xx” whereDIAGxx specifies the following:– VSM UsezOSV1R9Rules(Yes) – this is the z/OS 1.10 system default– Allocations are performed according to the current settingfor UsezOSV1R9Rules; prior allocations are not affectedby changing the DIAGxx value27 2009 IBM Corporation

IBM Systems & Technology GroupVSM Changes in z/OS 1.10Allocation Times 200k Data Sets - UsezOSV1R9Rules908070VSM USEzOSV1R9Rules YesMinutes6050403020VSM UsezOSV1R9Rules No100110192837465564738291100 109 118 127#Dsn (VSAM non-SMS) Allocations (in k)136 145 154 163 172 181190 199Z9 processor with 16 CPsVSM UsezOSV1R9Rules YES (R10 default)28 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 How can this change affect you? Properly coded programs can benefit from thesechanges. Some, such as DB2, may get a significantperformance benefit. This change can have a negative affect on someprograms which have made unwarranted assumptionsabout internal VSM behavior.1) These changes may give the perception in some cases thatstorage is not being cleared to zero as it previously was.However, storage is cleared by the system no differently inz/OS 1.10 than it was previously.2) These changes mean that a program cannot assume that aGETMAINed area ends on the last byte of the page; while thiswas never guaranteed, it was a common VSM behavior priorto z/OS 1.10.29 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 Cautionary Example #1– Do not assume storage is cleared to zeroesunless the GETMAIN either Is for 8192 bytes or more from a pageable, private storagesubpool. Is for 4096 bytes or more from a pageable, private storagesubpool, with BNDRY PAGE specified Specifies CHECKZERO YES and return code is 0.– Storage requests that previously returned anaddress on a freshly GETMAINed page (and wastherefore cleared to zeroes) may now return anaddress on an existing page that containsresidual (garbage) data.30 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10 Cautionary Example #2– Do not make start/end boundary alignmentassumptions based on the size of virtualstorage being allocated Use STARTBDY to specify the boundary theobtained storage must start on Use CONTBDY to specify the boundary theobtained storage must be contained within– Storage requests that previously returned anaddress that ended on the last byte of a pagemay now return an address that does notend on a page boundary.31 2009 IBM Corporation

IBM Systems & Technology GroupExample 2: VSM Low Private Storage Processing pre-z/OS 1.10Getmain for 8192 bytes fromsubpool 252 then freemain2048 bytes at address74F51800Getmain for 7168 bytes fromsubpool 252 returned virtualends on last byte of the page74F51FFF74F518002048 Bytes7168 Bytes6144 Bytes2 Pages74F53FFF2 Pages74F50000Returned Getmain Address 74F50000DQE A: Addr 74F50000 size‘2000’X (2 pages)1024 Bytes74F5240074F52000Returned Getmain Address 74F52400DQE B: Addr 74F52000 Size ‘2000’XFQE: Addr 74F52000 size ‘400’XFQE: Addr 74F51800 size ‘800’X32 2009 IBM Corporation

IBM Systems & Technology GroupExample 2: VSM Low Private Storage Processing z/OS 1.10Getmain for 7168 bytes fromsubpool 252: returned virtualdoes not end on a pageboundaryGetmain for 8192 bytes fromsubpool 252 then freemain2048 bytes at address74F5180074F51FFF74F540003072 Bytes4 Pages7168 bytes2048 Bytes74F518006144 Bytes2 Pages13312 Bytes74F53400ReturnedGETMAIN address 74F5180074F51800ReturnedGETMAIN address 74F5000074F50000DQE A: Addr 74F50000 Size 200074F50000DQE A: Addr 74F50000 Size 4000FQE: Addr 74F51800 size 800FQE: Addr 74F53400 size C0033 2009 IBM Corporation

IBM Systems & Technology GroupVSM GETMAIN Changes in z/OS 1.10SUMMARY of pre-z/OS V1R9 allocationbehavior:– Storage is more likely to be obtained from afresh page (which makes it more likely to becleared to binary zeroes)– Storage is allocated from the top (highaddress) of the page to bottom (loweraddress)– Unless a GETMAIN request can be satisfiedentirely from an existing FQE, a new DQEmust be obtained for each GETMAIN request34 2009 IBM Corporation

IBM Systems & Technology GroupVSM Diagxx Changes in z/OS 1.10SUMMARY of z/OS V1R10 allocation behavior: Using VSM UsezOSV1R9Rules(YES)– Same as pre-z/OS 1.10 Using VSM USEzOSV1R9Rules(NO)– Storage requests are more likely to be carved from areasthat were previously obtained with the GETMAIN requests(which means they may contain residual data).– Storage is allocated from the bottom (lower address) of thepage to top (higher address).– Storage requests may now be satisfied partly from an FQEallowing new allocation request to be merged into anexisting DQE35 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9 Problem Statement: Heavy usage of the CPOOL system service leads toCPU “Hot Cache Lines” for the CPOOL headers,degrading system performance Solution: Provide a multiple header option for CPOOL toeliminate the “Hot Cache Line” problem36 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9 Using CPOOL Service Enhancements customers areexpected to See improved performance in workloads involvingheavy usage of z/OS UNIX and/or GRS services Value: Customers are expected to get greater throughputon their systems leading to more transactions persecond, etc 37 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9 CPOOL Service Enhancements will allow a system componentor authorized application to: Use MULTIHDR YES on CPOOL BUILD to create a multipleheader Cell Pool Use MULTIHDR YES on CPOOL GET/FREE to get and freeelements from the Cell Pool Use CPOOL LIST, CPOOL DELETE, VSMLOC and IPCSRUNCPOOL functions against the multiple header Cell Pool38 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9CPOOL BUILD Newoption MULTIHDR YES causes creation of a cell pool with 256byte headers for the maximum number of CPUs allowed on thesystem Available to authorized callers only (System Key, APFAuthorized or Supervisor State) New keywords available with MULTIHDR YES only:only MAXCELLS nnnn indicates maximum number of cells to beallowed in cell pool before expansion will be stopped onconditional GET requests. CELLSPERCPU nnnn indicates the number of cells to beallocated per CPU extent39 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9CPOOL GET Newoption MULTIHDR YES causes the obtain of a cell from theheader associated with the running CPU COND YES callers will get a zero cell address returned if themaxcells limit has been reached for the cell pool and no cells arecurrently available for the running CPU40 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9CPOOL FREE Newoption MULTIHDR YES causes the release of a cell to theheader associated with the CPU it was obtained from41 2009 IBM Corporation

IBM Systems & Technology GroupVSM CPOOL Changes in z/OS 1.9CPOOL DELETE Causesthe deletion of the multiple header cell poolincluding the freeing of all cells and header storageCPOOL LISTReturns the list of extents allocated in the multiple headercell pool42 2009 IBM Corporation

IBM Systems & Technology GroupDIAGxx43 2009 IBM Corporation

IBM Systems & Technology GroupVSM ALLOWUSERKEYCSA(NO YES)– NO prevents user key CSA from being allocated byfailing any attempt to obtain user key from a CSAsubpool (through GETMAIN or STORAGE OBTAIN)with a B04-5C, B0A-5C, or B78-5C abend. The defaultis NO. IBM recommends that you should not specifyALLOWUSERKEYCSA(YES). User key CSA creates asecurity risk because any unauthorized program canmodify it.44 2009 IBM Corporation

IBM Systems & Technology GroupVSM BESTFITCSA(NO YES) Indicates how GETMAIN or STORAGE OBTAIN processrequests for (E)CSA storage. NO indicates to use a "first fit" algorithm in certain situationssuch as when the STARTBDY and CONTBDY options are used.This is the default, and matches the behavior on all currentreleases. However in some environments this can lead to(E)CSA fragmentation. YES indicates to always use a "best fit" algorithm. IBMrecommends that you specify YES for this option tominimize (E)CSA fragmentation and to prevent user andsystem outages due to requests for (E)CSA storage thatcannot be satisfied.45 2009 IBM Corporation

DIAGxx: VSM BESTFITCSACSA GETMAINs specifying STARTBDY or CONTBDY keywords are satisfied with a“best fit” algorithm by specifying VSM BESTFITCSA(YES) in the active DIAGxxmember of SYS1.PARMLIBFBQE1FBQENEXTFBQE3FBQEPREVFBQESIZE BQESIZE 1000FBQE4FBQEAREAFBQENEXTFBQESIZE 4000FBQEAREAEXAMPLE 1: GETMAIN for one 4K page, e.g.?GETMAIN(RC) A(DATA2) LV(1000) SP(231) CONTBDY(9) STARTBDY(4);FBQEPREVFBQESIZE 2000FBQEAREA VSM BESTFITCSA(NO) (default behavior): satisfied from FBQE1 VSM BESTFITCSA(YES): satisfied from FBQE3 (an exact fit)EXAMPLE 2: GETMAIN for three 4K pages, e.g.?GETMAIN(RC) A(DATA2) LV(3000) SP(231) CONTBDY(9) STARTBDY(4); VSM BESTFITCSA(NO) (default behavior): satisfied from FBQE1 VSM BESTFITCSA(YES): satisfied from FBQE246

64-Bit VSM/RSM47

IBM Systems & Technology Group64-Bit Address Space Memory Map– z/OS virtual memory above2GB is organized as memoryobjects which programscreate. User Privatea memory object is acontiguous range of virtualaddressesthey are allocated as anumber of application pageswhich are 1MB on a 1MBboundaryShared Area64-Bit CommonUser Private23223148ReservedBelow 2GThe Bar 2009 IBM Corporation

IBM Systems & Technology Group64-Bit Memory Object Operations (IARV64) Managing Memory Objects– Getstor - create a Private Memory Object (only for private memoryobjects)– Changeguard - increase or decrease the amount of usable memoryin a memory object (only for private memory objects)– Getshared – create a Shared Memory Object (only for sharedmemory objects)– Sharememobj - allows an address space to access Shared MemoryObjects (only for shared memory objects)– Changeaccess - manages the type of access an address space hasto the Shared Virtual Storage (only for shared memory objects)– Getcommon- create a Common Memory Object (only for commonmemory objects)– Detach - delete Memory Objects (applies to all memory objects:private, shared, common ) 2008 IBM Corporation49

IBM Systems & Technology GroupIARST64/IARCP64 in z/OS 1.10 Problem: Virtual Storage Constraint- as we strive for Virtual Storage Constraint Relief (VSCR), manycomponents will be asked to move their blocks above the bar- every user of 64 bit storage will have to write their own storagemanager to hand out smaller pieces of the storage to their application Solution: Provide a set of services that will allow components to obtainstorage as needed without having to write their own storage manager- IARST64 – allows the caller to request private or common storage insizes from 1 byte to 64K.- IARCP64 – allows the caller to create a private or common storagecell pool with cells in sizes from 1 byte to almost half a meg Benefit: These services will help free up storage below the bar 2008 IBM Corporation50

IBM Systems & Technology GroupIARST64/IARCP64 in z/OS 1.10 Using 64 Bit Storage Services, the customer can:1. request private or common storage in sizes from 1 byte to64K2. create a private or common storage cell pool with cells insizes from 1 byte to almost half a meg Value:1. alleviate virtual storage constraint below the bar2. components obtain storage as needed without having towrite their own storage manager 2008 IBM Corporation51

IBM Systems & Technology GroupIARST64/IARCP64 in z/OS 1.10 IARST64 (assembler and PLX macro)– equivalent of GETMAIN/FREEMAIN or STORAGEOBTAIN/RELEASE for 64 bit storage– GET/FREE 1 to 64K bytes of private or common– Full doc in macro prolog IARCP64 (assembler and PLX macro)– equivalent of CPOOL for 64 bit storage– BUIILD/GET/FREE/DELETE a pool supporting cells 1 byte to½ meg of private or common– Full doc in macro prolog 2008 IBM Corporation52

IBM Systems & Technology GroupJAVA Pointer Compression - Overview Problem Statement / Need Addressed:– JAVA can improve their performance by using 64-bit storage– Using 32 bit pointer compression, JAVA can accessaddresses in the 2G-32G range without incurring theperformance cost of using 64-bit addresses– Need a way to explicitly request storage in the 2G-32G range Solution:– RSM will allow JAVA to explicitly request 64-bit storage in the2G-32G area (via an internal interface) Benefit:– Improved performance with JAVA by allowing the use of 64bit storage53 2009 IBM Corporation

IBM Systems & Technology GroupJAVA Pointer Compression - Component Externals64-Bit Address Space Memory MapAs a result of this support,the boundary for the lowuser private area above 2Gis now 235 instead of 232.User PrivateMemory objects allocatedby JAVA will start atx’80000000’.Non-JAVA requests willstart at x’8 00000000’Shared Private64-bit Common235231User PrivateReservedBelow 2G54 2009 IBM Corporation

IBM Systems & Technology GroupJAVA Pointer Compression - Installation This enhancement is available in the z/OS v1r11(HBB7760) release. In addition, it is available via APAR OA26294:– PTFs: UA44790 for HBB7730 (z/OS v1r8) UA44791 for HBB7740 (z/OS v1r9) UA44792 for HBB7750 (z/OS v1r10)55 2009 IBM Corporation

IBM Systems & Technology Groupz/OS 1.12 Changes to IARV64 GETSTOR Problem Statement / Need Addressed:– Today’s fork 64-bit copy processing fails when highvirtual storage is allocated in the child space at thetime when the copy of the parent 64-bit virtual iscopied into the child space RSM fails the copy with Return Code 8 Reason code‘6E000300’x – Child address space contains memoryobjects that were previously allocated Forks fails with Return code 70 Reason code‘0B1505C1’x - An invocation of IARV64FC servicefailed. Action: Retry the operation at a later time 2009 IBM Corporation

IBM Systems & Technology Groupz/OS 1.12 Changes to IARV64 GETSTORTask structure forfork initiatoraddress spaceDumpDump1.2.3.4.RCTTCBCross memoryresources ownerTCBASCBXTCBJob Step TCBRuns InitializationCalls Fork ExitsPost parent that I amready for copyWait for copy to be doneSTCINIT TCBAttachesJob StepTCB (JST) 2009 IBM Corporation

IBM Systems & Technology GroupOverviewAs a result of this support, anew system area will becreated in the address space64-bit mapMemory objects allocated inthe System Area will start atx’8 00000000’64-Bit Address Space Memory Map64-Bit User Private Area512TBDefault 64-Bit Shared Area2TBDefault 64-bit Common Area1982G64-Bit User Private Area288GSystem Area32G2GReserved for JVM useBelow 2G 2009 IBM Corporation

IBM Systems & Technology Groupz/OS 1.12 Changes to IARV64 GETSTOR Solution:– A new keyword will be added to the IARV64REQUEST GETSTOR, LOCALSYSAREA NO YES to indicatethat the memory object should be allocated from the SystemArea of the 64-bit address space map (Note: Only authorizedusers may use this new keyword)– When LOCALSYSAREA YES is specified, MEMLIMIT is ignored– During the 64-bit copy phase for fork processing memoryobjects that are allocated in the system area will not be copiedto the child space– Fork will fail only if the child has 64-bit memory objectsallocated in the User Private Area– Checkpoint restart will fail only if RACF builds generic profiletables allocated in the User Private Area Benefit:– Allows fork processing to continue to use 64-bit virtual underany circumstance 2009 IBM Corporation

IBM Systems & Technology GroupAppendix 1Monitoring Common Storage Usage viaCSA Tracker and IPCS 2008 IBM Corporation60

IBM Systems & Technology GroupCommon Storage Tracker (or CSA Tracker) Tracks owners of currently GETMAINed SQA/ESQAand CSA/ECSA storage– Address and length of GETMAINed storage– ASID, jobname, and PSW address of owner– Time and date of GETMAIN Activated via DIAGxx parmlib member– Can be activated/deactivated at any time– DIAGxx: VSM TRACK CSA(ON) SQA(ON)– SET DIAG XX 2008 IBM Corporation61

IBM Systems & Technology GroupCSA Tracker Terminology S – SQA C – CSA AC - Active storage; the address space that performed thestorage request is still active OG - Owner Gone storage; the address space that performed thestorage request has terminated SYSTEM-OWNED storage - storage obtained by the system (e.g.dispatcher, IOS, timer) and not related to a specific address space NO DETAIL storage - storage for which CSA tracker has noinformation; perhaps it was obtained early in IPL before trackerwas activated CAUB - an internal VSM control block 2008 IBM Corporation62

IBM Systems & Technology GroupFormatting CSA Tracker Data VERBX VSMDATA 'OWNCOMM DETAIL'– Formats a detailed report of global storage usage– Identifies how much SQA, ESQA, CSA, and ECSA storage isowned by. The system Non-system functions Owner gone functions (owning address space has terminated)– For each acquired area of global storage, gives. Storage address and

Storage Types (all with respect to z/OS ’spoint of view) Virtual memory/storage DAT -on addressing Explicitly allocated either by the system or applications 24, 31, or 64 bit residency mode (rmode ) 31 -bit virtual is allocated/freed in multiple of 8 byte ch

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Cost Transparency Storage Storage Average Cost The cost per storage Cost Transparency Storage Storage Average Cost per GB The cost per GB of storage Cost Transparency Storage Storage Devices Count The quantity of storage devices Cost Transparency Storage Storage Tier Designates the level of the storage, such as for a level of service. Apptio .

A smarter way to manage storage. IBM Virtual Storage Center enables organizations to make an easy transition to cloud-enabled, software- defined storage environments— because it is both a storage virtualization platform and a storage manage-ment solution. Virtual Storage Center is designed to support the new

Specify the size of the new virtual disk. Press the OK button to finish the wizard. A virtual machine is built. Note that before Version6.5 in the Storage labels of your virtual machine, you need to exchange the position of iSCSI Virtual Storage and Local Storage (make sure iSCSI Virtual Storage at position 0) so that

Python Basics.ipynb* Python Basics.toc* Python Basics.log* Python Basics_files/ Python Basics.out* Python_Basics_fig1.pdf* Python Basics.pdf* Python_Basics_fig1.png* Python Basics.synctex.gz* Python_Basics_figs.graffle/ If you are reading the present document in pdf format, you should consider downloading the notebook version so you can follow .

Each NETLAB remote PC or remote server runs inside of a virtual machine. VMware ESXi provides virtual CPU, virtual memory, virtual disk drives, virtual networking interface cards, and other virtual hardware for each virtual machine. ESXi also provides the concept of a virtual networking switch.

"Virtual PC Integration Components" software must be installed into each virtual machine. In a Windows host, the "Virtual PC Integration Components" software for a Windows virtual machine is located at C:\Program Files (x86)\Windows Virtual PC\Integration Components\ Multiple virtual machines can access the same target folder on the host.

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