ims fundamentals - availability
TRANSCRIPT
Course materials may not be reproduced in whole or in part without the prior written permission of IBM. 5.1
© Copyright IBM Corporation 2008
Enhancing IMS Availability
© Copyright IBM Corporation 2008
Objectives
• See how Concurrent Copy can be used to increase IMS database availability
• Know and differentiate between XRF (Extended Recovery Facility) and RSR (Remote Site Recovery).
• Learn about Data Sharing among multiple IMS subsystems and how it evolved into IMS Parallel Sysplex Data Sharing.
• See how IMS Shared Queues and other IMS functions can use IBM Coupling Facilities to share information between IMS systems.
• Discover the features of the IMS Common Service Layer (CSL) Architecture and how CSL can aid in managing an IMSPLEX.
• Learn how the Operations Manager address space provides the ability to issue IMSPLEX-wide commands through the SPOC interface.
© Copyright IBM Corporation 2008
DFSMS Concurrent Copy Support
• DFSUDMT0 - Database Image Copy 2 Utility– Invokes DFSMSdss DUMP to create copy of data set– Can produce consistent (clean) or concurrent (fuzzy) image copy
• Clean image copy requires/DBR until logical copy completes• Fuzzy image copy does not require/DBR• To get fuzzy image copy of KSDS
DEFINE (ALTER) CLUSTER ..... BWO(TYPEIMS)– IMS database data sets supported
• HDAM, HIDAM, HISAM, DEDB• OSAM, ESDS, KSDS
– Will produce 1-4 copies• Two copies registered with DBRC at completion of DUMP• Additional copies can be available for shipment offsite
© Copyright IBM Corporation 2008
Typical IMS Failure & RecoveryProcessing Center End-User Activity
Problem occurs @%&*#!!%Problem detection No response Z Z ZOperational decisionProblem determination Phone HELP DeskFault isolation @%&*#!!% Z Z
Reconfiguration or repair Coffee Phone againRe-IPL of z/OS systemRestart of IMS/TMRe-synchronize databases @%&*#!!%Restart networkReconnect End-usersReenter lost work Where am I ?Resume What was I doing? Resume
© Copyright IBM Corporation 2008
NETWORK (WITH XRF SWITCH)
PRIMARYSESSIONS
BACKUPSESSIONS
VTAM1
IMS1
(ACT)IMS2
(ALT)
LOWERPRIORITY
WORKLOADISC LINK
(OPTIONAL)
IMSONLINE
LOGDATASETS
IMSDATABASEDATA SETS
zOS1 zOS2
LOG TRACK
UPDATESPASSIVECONNECTION
INTERACTIVE END USERS
VTAM2
Steady State: Before Takeover
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NETWORK (WITH XRF SWITCH)
OLD "ACTIVE" SESSIONS
PRIMARYSESSIONS
VTAM1
IMS1 (OLD ACT)
IMS2 (NEW ACT)
IMS ISC LINK
(OPTIONAL)
IMS
ONLINELOG
DATASETS
IMSDATABASEDATA SETS
zOS1 zOS2
GET IN SYNC
DB BACKOUT AND RECOVERY
INTERACTIVE END USERS
VTAM2
| X |
During Takeover
© Copyright IBM Corporation 2008
NETWORK (WITH XRF SWITCH)
PRIMARYSESSIONS
VTAM1
VTAM2
IMS2(ACT)
zOS1 zOS2
UPDATES
INTERACTIVE END USERS
LOGIMS
ONLINELOG
DATASETS
IMSDATABASEDATA SETS
After Takeover
© Copyright IBM Corporation 2008
NETWORK (WITH XRF SWITCH)
PRIMARYSESSIONS
BACKUPSESSIONS
IMS1
(ALT)
VTAM2
IMS2
(ACT)
LOWERPRIORITY
WORKLOAD IMSISC LINK
(OPTIONAL)
zOS1 zOS2
LOGTRACK
UPDATESPASSIVECONNECTION
INTERACTIVE END USERS
IMS
ONLINELOG
DATASETS
IMSDATABASEDATA SETS
VTAM1
Steady State: After Takeover
© Copyright IBM Corporation 2008
Remote Site Recovery
• RSR Database Support– Database Level Tracking (DLT)
• RSR provides remote database shadowing• Reduces service outage to minutes• Requires dedicated DASD for databases while tracking
– Recovery Level Tracking (RLT)• User must recover databases following a takeover• Service outage will be measured in hours• Does not require dedicated DASD for databases while tracking
• Level of support selectable by database• Level of support defined in DBRC RECONs and can be
changed dynamically
© Copyright IBM Corporation 2008
Data Sharing Definition
• “The DATA SHARING facility allows multiple application programs in different IMS and/or CICS subsystems to concurrently process common DL/I databases with full integrity.”
• DATABASE-LEVEL SHARING– DBRC controls used of database
• BLOCK-LEVEL DATA SHARING– IMS Resource Lock Manager (IRLM) provides “global” Program
Isolation (PI)
• IRLM, and IMS Data Sharing have been available since IMS 1.2 (about 1980)
© Copyright IBM Corporation 2008
USERTERMINAL
USERTERMINAL
MASTERTERMINAL
USERTERMINAL
z/OS
IMS/TM DBRC DLISAS IMS/BATCH
IMS/MPR
DL/I
AP
PL
APPL
MSGQUEUE RECON
IMSDB(S)
CORPORATEDATA BATCH
DB(S)
APPL
CICS
DL/I
Data Sharing Definition
© Copyright IBM Corporation 2008
DBRC Share-Level Options• DATABASE-LEVEL SHARING
– SHARELVL(0)• Guarantees EXCLUSIVE use
– SHARELVL(1)• 1 updater; multiple Read-Only (RO)• Multiple readers, RO and/or Read w/Integrity (RD)
• BLOCK-LEVEL DATA SHARING
– SHARELVL(2)• Multiple UP/RD/RO• Maximum 1 z/OS system image• INTRA-system, DBRC, one IRLM
– SHARELVL(3)• Multiple UP/RD/RO• MULTIPLE z/OS system images• INTER-system, two IRLMs, VTAM "connection"
© Copyright IBM Corporation 2008
z/OS 1 z/OS 2 z/OS 3
IMS2 IMS3
DBRC
MPRBMPIFP DBRC
MPRBMPIFP
RECON
IMS DBSOR
FP DEDB
SHARELVL(1)
OR
–ALL SUBSYSTEMS MAY "READ WITH INTEGRITY"
DL/I BATCH
READ-ONLYW/O INTEGRITY READ-ONLY
W/O INTEGRITY
IMS1
DBRC
UPDATER
Database-Level Sharing
© Copyright IBM Corporation 2008
z/OS 1
DBRC
OnlineS/S
DBRC
OnlineS/S
DBRC
ONE z/OS SYSTEM:
OnlineS/S Batch
RECON
IMS DBSOR
FP DEDB
SHARELVL(2)
IRLM
Intra-System Block-Level Data Sharing
© Copyright IBM Corporation 2008
ONLINES/S
DBRC
IRLM
VTAM
ONLINES/S
DBRC
IRLM
VTAM
RECON
IMS DBSOR
FP DEDB
SHARELVL(3)
z/OS 1 z/OS 2
Inter-System Block-Level Data Sharing
© Copyright IBM Corporation 2008
Data Sharing Summary
• Other Data Sharing subsystems could be:– IMS DBCTL– IMS TM– Off-Line Batch (DBBBATCH/DLIBATCH)– Selected IMS utilities, such as CIC
• IRLM is required for Block-Level Data Sharing• Increased system availability:
– More operational flexibility via separate subsystems– Failure isolation via separate subsystems
© Copyright IBM Corporation 2008
VTAM
IMS TM
MSG Queue
IMS DB
Lock Manager
z/OS
VTAM
IMS TM
MSG Queue
IMS DB
Lock Manager
z/OS
VTAM
IMS TM
MSG Queue
IMS DB
Lock Manager
z/OS
DB2
LocksDirectories
Coupling Facility
IMSDATA-BASE
DB2DATA-BASE
Allocationof
workstations
IMS DBData
Sharing
Easier access and management of enterprise IMS DB data
MSG
MSG
MSG
IMS in a Parallel Sysplex
© Copyright IBM Corporation 2008
N-Way Data Sharing
• IMS/ESA Version 5 allowed up to 32 IMS subsystems distributed among, at most, 32 z/OS images, in a z/OS sysplex, to share databases.– current limit is 64– Sharing across more than two z/OS images ("LPARs") requires the
use of the S/390 - z/OS Coupling Facility technology• IMS/ESA Version 5 introduced a new IRLM (Version 2.1)
– IRLM Version 2.1 can currently communicate with up to 63 other instances of IRLM Version 2.1, using Coupling Facility technology
– "Old" IRLM (Version 1.5) was discontinued with IMS Version 7• Data sharing is supported among all IMS versions
– Block level data sharing logic (what locks are obtained when) was not changed between IRLM V1.5 and V2.1
© Copyright IBM Corporation 2008
IMS A IMS B
Database
IRLM A IRLM BC Q S A C Q S B
OSAMCACHE
Structure
OSAMBlock X
CF
OSAM Caching
© Copyright IBM Corporation 2008
CF
IMS A IMS B
IRLM A IRLM BC Q S A C Q S B
D E D B
V S Oin Cache
Database
Shared VSO (Virtual Storage Option)
© Copyright IBM Corporation 2008
Coupling Facility
IMSASyste
m
IMSCSyste
m
IMSBSyste
m
IMSDSyste
m
N-Way DataSharing
Database
What happens when IMSA fails?
==> Answer: Its Locks are retained!!! <==
Impact of an IMS Failure with Data Sharing
© Copyright IBM Corporation 2008
IMS D
IMS C
IMS B
IMS A
SHAREDDATABASE
IMS A failedbut
UPDATE-LOCKsare held by CF for
this databaserestart
(/ERE & backout)of IMS A
If applications ofIMS B, IMS C or IMSD
request datalocked by IMS A
they will get U3303
(LOCK REJECT)
U3303
U3303
U3303
IMS Lock Reject - ABEND U3303
© Copyright IBM Corporation 2008
IRLM
IRLM
FDBR
CTL
MPRs
BMPs
DLI
DBRC
CF
LockStructur
es
Active IMS Fast DB Recovery
SharedDatase
ts
Shared Datsetsƒ OLDSƒ WADSƒ RDSƒ RECONƒ ACBLIBƒ MODBLKSƒ MODSTATDatabases
FDBR can be installed on same or
different z/os
ƒ FDBR Configuration
Fast Database Recovery (FDBR) in Sysplex
© Copyright IBM Corporation 2008
FDBRA
IMSA
z/os A
FDBRB
IMSB
z/os B
FDBRC
IMSC
z/os C
FDBRD
IMSD
z/os D
FDBRE
IMSE
z/os E
FDBR on same z/os as active IMS
Note:NOT recommended for production
FDBR Configuration: Sample 1
© Copyright IBM Corporation 2008
FDBRE
IMSA
z/os A
FDBRA
IMSB
z/os B F
DBRB
IMSC
z/os C
FDBRC
IMSD
z/os D
FDBRD
IMSE
z/os E
FDBR configured as a ring
Note:Best Configuration for production
FDBR Configuration: Sample 2
© Copyright IBM Corporation 2008
IMS AMSGQ
TX A1 LTERM
IMS BMSGQ
Shared
DB
TX B1 LTERM
IMS A
IMS B
SharedQueue
Structure
Shared
DB
MSGB1 MSGA1
CF
LTERMA LTERMB
processing
w/o w/
IMS C
IMS Shared Queues
© Copyright IBM Corporation 2008
A set of input and output message queues which can be shared by multiple IMSs in a Parallel Sysplex.
Coupling Facility
QUEUES
ListHeaders Messages
IMS2 IMS3IMS1
What are Shared Queues?
© Copyright IBM Corporation 2008
IMS3
TRANX queueis shared byall MPPsin any IMScapable ofprocessing it.
Output messagegoes on LTERMqueue for delivery by IMSwhich is in session withLTERMZ
Shared MSGQueue StructureCoupling Facility
LTERMZ
TRAN-Q RESPX LTERM-QTRANX
IMS2IMS1
IMS1MPP
IMS2MPP
IMS3MPP
IMS1MPP1
IMS2MPP1
IMS3MPP1
TRANX
RESPX
(1)
(2) (3)
(1)
MPP1 in IMS2 is first to ask for TRANX
Shared Message Queues - Example
© Copyright IBM Corporation 2008
Common CQS Data Sets
IMS2
Coupling Facility
IMS1
EMHQCKHPT MSGQ
CKHPT
MSGQCKHPT
EMHQCKHPTMSGQ
SRDS1EMHQSRDS1
MVSLOGLOGGER
SPILL
MVSLOG
MVSLOGLOGGER STAGING
MSGQ Logger Structure
EMHQ Logger Structure
MSGQ OFLW Structure
EMHQ OFLW Structure
OLDSMSGQ Primary Structure
EMHQ Primary Structure
LOGGER STAGING
IMS3
OLDS
OLDS
IMS V10
IMS V9
IMS V10
CQS1
LOGGER V9
LOGGER
CQS2
V9
Shared Queues Components
© Copyright IBM Corporation 2008
ƒ All IMSs in a Sysplex Environment are belonging to a Generic Resource Group
ƒ IMS-User logons to a Generic Resource Name for the IMS Sysplex
ƒ VTAM establishes a connection to a member of the group (e.q. IMSA)
IMS A IMS B IMS n
VTAMwith Generic Resource Support
CF
Coupling Facility
LOGON IMS
VTAM Generic Resource (VGR)
© Copyright IBM Corporation 2008
IMS A IMS B IMS n
VTAMwith Generic Resource Support
LOGON IMS
LU1 LU2 LU3 LU4
IMS B fails
User connected to LU1 oncemore has to logon to VTAM Resource Group
User/LU1 will be connected to a surviving IMS (not IMSB)
= Cloned Systems
CF Coupling Facility
User Impact with VGR
© Copyright IBM Corporation 2008
IMS2DBRC
CQS2
LOGR
CQS1
LOGR
VTAMTCP/IP
TRANSACTION
Network
IMS3DBRCIMS1
DBRC
VTAMTCP/IP
IMSCONNECT
XCF
LOGSMQ
OSAMVSAMSVSOLOCKVGR
MNPS
IMSplex
IMS Sysplex Components
• IMS uses many parallel sysplex functions to share resources in an IMSplex– Data sharing, shared queues– VTAM generic resources, multinode persistent sessions– Automatic restart management, XCF communications
© Copyright IBM Corporation 2008
IMS1
IMS3 IMS4
IMS2
Network
DBSMQ
Shared Resources
MTO
EndUser
SystemConsole
E-MCS
@DBR DB XYZ
/STA DB 18/STOP NODE
/STA TRAN
/DIS STATUS
AUTOMATION
Managing Shared IMS Resources
• But managing these resources became more difficult– Systems management functions needed to be more robust
© Copyright IBM Corporation 2008
The IMSplex
• Definition of an IMSplex– An IMSplex is a set of IMS address spaces that are working together
as a unit and are most likely running in a parallel sysplex with a common service layer (CSL)• Note: The IMSplex is not new, we're just now formalizing the term
– Examples of an IMSplex include ...• A set of IMS control regions without a CSL that are data sharing or
message queue sharing
• A set of IMS control regions without the CSL that are data sharing or message queue sharing with IMSs with a CSL
• A set of IMS control regions with a CSL that are data sharing or message queue sharing
• A single IMS control region with a CSL
© Copyright IBM Corporation 2008
Common Service Layer (CSL)
• The next step in IMS architectural evolution– Address spaces built using the Base Primitive Environment (BPE)
• Structured Call Interface (SCI)– IMSplex member registration– Communications between IMSplex members
• Operations Manager (OM)– IMSplex-wide command entry and response
• Resource Manager (RM)– Global resource and process management– VTAM terminal/user status recovery
– Enables systems management functions in IMSplex• Sysplex Terminal Management (STM)
– Uses SCI and RM• Single point of control (SPOC) and user-provided automation (AOP)
– Uses SCI and OM• Coordinated Online Change (Global Online Change)
– Uses SCI, OM, and RM• HALDB Online Reorganization (Online Reorg)
– Uses SCI and OM
© Copyright IBM Corporation 2008
SCI
DBRC
SCI
CommonQueueServer(CQS)
OperationsManager
(OM)
SCI
IMSControlRegion
SCI
ResourceManager
(RM)
SCI
StructuredCall
Interface
SCI
Online DBRCDBRC Batch UtilityBatch with DBRCUtility with DBRC
Global Online ChangeSysplex Terminal Management
CommunicationsAutomatic RECON Loss NotificationSPOC
Automation
MasterTerminal
End UserTerminal
SCICommunications
Automation
SPOC
New CSLaddress spaces
CF
CQS
SCI
IMS
CouplingFacility
New function
ResourceLOGRSMQ
OSAMVSAMSVSOIRLMVGR
CSL Architecture
© Copyright IBM Corporation 2008
IMSCTL
SCI
SCI
CQS
OM
SCI
IMSCTL
SCI
RMSCI
SCISCI
SCI
CQS
OM
SCI
RMSCI
SCISCI
SCI
CQS
OM
SCI
RMSCI
SCISCI
SCI
CQS
OM
SCI
RMSCI
SCISCI
CF
XCF
XCF
XCF XCF
SCI
SCI SCI
ResourceList Structure
LOGRList Structures
SMQList Structures
OSAMCache Structure
VSAMCache Structure
Shared VSOCache Structures
IRLMLock Structure
VGRList Structure
IMSCTL
SCI
IMSCTL
SCI
SCI
IMSplex Configuration
• In an IMSplex– All members share the same CF structures– Intra-IMSplex communications is implemented by SCI using XCF
across OS images
© Copyright IBM Corporation 2008
CSL Component – Operations Manager
• Operations Manager (OM)– Provides an API supporting common point of command entry
• Focal point for operations management and automation• Command responses from multiple IMSs are consolidated
– Provides the following services to members and clients of an IMSplex• Provide an API for IMS commands submitted from outside IMS
– Classic ("Type 1") IMS commands (/cmd ...)– New ("Type 2")IMSplex commands (QRY, INIT, TERM, DEL, UPD)
• Command registration to support any command processing client– Clients tell OM which commands it can process
• Command security – Perform authorization within OM - before sending to IMS– RACF or user-written command security exit
• Route commands to IMSplex members registered for the command• Consolidate command responses from individual IMSplex members into
a single response to present to the command originator
© Copyright IBM Corporation 2008
SPOC Features
• The SPOC application ...– Allows user to set preferences– Allows the user to specify shortcuts and set default command
parameters– Allows user specified grouping of IMSplex members– Allow the user to enter commands to one or more IMSs– Displays consolidated IMSplex and classic IMS command responses– Allows the user to sort IMSplex command response by column– Keep a history of commands– Allows the user to enter long commands
© Copyright IBM Corporation 2008
Unit Summary• Concurrent Copy can be used to increase IMS database
availability.• XRF (Extended Recovery Facility) and RSR (Remote Site
Recovery) are features that enhance IMS availability .• Parallel Sysplex allows up to 64 IMS subsystems to share
databases• Shared Message Queues allows all IMSs in a Parallel Sysplex
to share the same message queue• Shared VSO, OSAM Caching, and VTAM Generic Resources
are additional IMS functions that use IBM Coupling Facilities to share information between IMS systems.
• The IMS Common Service Layer (CSL) Architecture is a collection of new IMS Address Spaces that provide global functions that can aid in managing an IMSPLEX.
• The Operations Manager is a new CSL address space that provides the ability to issue IMSPLEX-wide commands through the SPOC interface