IMS Plex and Shared Queues
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IMS Plex and Shared Queues

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    IMS Plex and Shared Queues IMS Plex and Shared Queues Presentation Transcript

    • IMS Plex and Shared Queues Jack Pinto David Sosa Marilene Noronha Roder IMS Silicon Valley laboratory San Jose, California IMS Latin America Road Show October, 2009
    • IMS – High Availability Configurations
      • IMS subsystem has multiple features to eliminate planned outages and minimize the impact of unplanned outages
        • Multiple cloned IMSs in Parallel Sysplex
        • Data sharing
        • Fast database recovery (FDBR) or
        • Extended Recovery facility (XRF) – not both
        • Automatic Restart Manager (ARM) support
        • Shared Queues
        • Online change
        • Common Service Layer (CSL)
        • Dynamic Resource Definition
      • Cloned IMSs
        • All IMSs can use a single system definition
        • Definitions which must be unique can be redefined at execution time with runtime parameters
          • For example, master and secondary terminal definitions
        • With common definitions, all applications can run on any IMS
          • Reduces impact of planned or unplanned outage
        • Easier to roll maintenance across the IMSplex
      IMS – High Availability Configuration
    • IMS – High Availability Configuration
      • Data sharing
        • Every database is available from every IMS
          • All IMS database types can be shared, except MSDBs
        • Fast database recovery (FDBR)
          • One per active IMS
          • Monitors active IMS data sharing system (reads OLDS)
          • In event of IMS or system failure
            • Backs out inflight work
            • Releases IRLM retained locks
      IRLM IRLM CF DB FDBR1 OLDS IMS1
      • Automatic restart management (ARM)
        • Automatically restarts IMS after system or IMS failure
        • ERE required even with FDBR
          • Resolve in-doubts with CICS and DB2
          • Release database authorizations
        • Supports all IMS address spaces (IMS, CSL, SQ, FDBR)
        • Saves time frequently spent (wasted) thinking about what to do
        • Can “group” subsystems to restart on same LPAR in event of system failure
          • IMS, CICS, DB2, MQ (with IMS Adapter)
      IMS – High Availability Configuration
      • Shared queues
        • All IMSs queue input and output messages on shared queue structures in Coupling Facility
          • Full function and fast path EMH
        • All messages are available to all IMSs
          • Some exceptions (e.g., SERIAL transactions)
        • Minimizes input queue times for transactions
          • If front-end IMS busy, back-end can schedule transaction
        • In event of failure (System or IMS)
          • Users can reconnect to another IMS and continue work
          • High availability connectivity configuration makes reconnecting easy or transparent
        • When used with CSL and Resource Manager
          • Command and end-user status can follow user to new IMS
      IMS – High Availability Configuration
    • IMS Shared Queues Single image to end user!
      • Common Service Layer (CSL)
        • Structured Call Interface (SCI)
          • Automatic RECON Loss Notification (ARLN)
            • Notifies all DBRCs when any one DBRC reconfigures RECONs
            • Each DBRC switches RECONs and deallocates
        • Operations Manager
          • Single point of control for all IMSs
          • Required for Type-2 commands
            • INIT OLC, INIT OLREORG
            • CREATE and DELETE
            • UPDATE resource attributes and status
            • QUERY resources and environment
          • SCOPE(ALL) command support
            • Command processed on all IMSs
      IMS – High Availability Configuration
      • Common Service Layer (CSL) ...
        • Resource Manager
          • Global online change
            • Coordinates PREPARE and COMMIT phases across all IMSs
            • All succeed or all fail
          • Sysplex terminal management (STM)
            • Manage resources across IMSplex
            • Significant status follows user to another IMS
              • Command status
              • End-user status (CONV, FP RESP, STSN)
          • Global status (V10)
            • Status of MODBLKS resources maintained in Resource Structure
              • Databases, programs, transactions, routing codes
            • Status known to all IMSs
      IMS – High Availability Configuration
      • Online change
        • Coordinated global online change (requires CSL)
          • Add, change, delete resources
          • Switch libraries
          • All resources quiesced during part of process
          • Coordinated across all IMSs
        • Member online change for ACBLIB (IMS V10 – requires CSL)
          • Add or change individual PSBs and DBDs
          • Update made directly to ACBLIB – no switch
          • Only affected resources are quiesced
          • Coordinated across all IMSs
      IMS – High Availability Configuration Member OLC is discussed in more detail in Part 2.
      • Dynamic resource definition (DRD)
        • Dynamically create or delete resource definitions using Type-2 commands
          • CREATE, DELETE
            • Databases (DDIR)
            • Programs (PDIR)
            • Transactions (SMB)
            • Routing Codes (RCTE)
        • Dynamically update resource attributes using Type-2 command
          • UPDATE
            • Same resource types
            • MSC definitions
        • Online change process not required
      IMS – High Availability Configuration DRD is discussed in more detail in Part 2.
    • Rolling Maintenance
      • IMSplex offer opportunity to roll maintenance through sysplex without losing availability
        • Notify users of intent to shut down IMS1 (for example)
        • VTAM users log off and back on to IMS generic resource name when convenient
          • VGR routes logon to IMS2 or IMS3 or ....
        • TCP/IP users not affected
          • IMS Connect will always select available IMS
        • Shutdown IMS1
        • Restart IMS1 with new maintenance and /START DC
        • Repeat process for IMS2, IMS3, etc.
      • Works for IMS and system maintenance
        • May need two step process when migrating to new release of IMS
          • Step 1 – roll pre-req maintenance to all IMSs
          • Step 2 – roll new IMS libraries through each IMS
    • The IMSplex Shared-Everything Environment Looks like single image to end users! IMS1 Environment IMS2 Environment IMS4 Environment IMS3 Environment Network DB SMQ Shared Resources Shared Operations I M S
    • The IMSplex Shared-Everything Environment In case of planned or unplanned outage, user still has access to all the data and applications. IMS1 Environment IMS2 Environment IMS4 /CHE FREEZE IMS3 Environment Network DB SMQ Shared Resources Shared Operations I M S
    • The Key To High Availability
      • Minimize impact of unplanned outages
        • Multiple images (more baskets)
        • Less pervasive
        • Faster recovery
        • BE PREPARED
      • Eliminate planned outages
        • Rolling maintenance
        • Online resource definition changes
        • Online database tools
        • Faster database tools