Upgrading a CICSplex with a running workload

The scenario uses the abilities of CICSPlex® SM to route work to any available target region, and to continue to route work, even when the maintenance point CMAS is offline. It is possible to upgrade only the CICSPlex SM component and defer the upgrade of CICS® regions. This scenario upgrades both at the same time.

About this scenario

This scenario aims to demonstrate a general upgrade workflow and process that you can adapt for your own environment when you upgrade CICSPlex SM components and CICS regions in a CICSplex to a higher release.

This scenario is based on a CICSplex environment that spans two logical partitions (LPARs), as illustrated in Figure 1. LPAR 1 contains the maintenance point CMAS (MP CMAS) and the CICSPlex SM WUI server. Both LPARs contain a non-MP CMAS, several terminal-owning regions (TORs) that are connected to a number of target CICS application-owning regions (AORs). To streamline the diagrams, connections between LPARs are not shown.

Figure 1. Example CICSplex configuration
The diagram shows two logical partitions (LPARs) in which CICS workload is running. LPAR 1 contains the MP CMAS and the WUI. Both LPARs contain a non-MP CMAS and several TORs that are connected to a number of target AORs.

The two LPARs have a shared CICS system definition file (CSD).

LPAR 1 hosts the following regions:
  • Two CMAS regions, one of which is the MP CMAS. The non-MP CMAS on LPAR 1 connects to both the MP CMAS and the CMAS on LPAR 2.
  • Three TORs. These regions are linked to all AORs on LPAR 1 and LPAR 2.
  • A CICSPlex SM WUI server.
  • Several AORs. These regions are linked to, from TORs on LPAR 1 and LPAR 2.
LPAR 2 hosts the following regions:
  • One CMAS. This CMAS connects to the two CMAS regions on LPAR 1.
  • Three TORs. These regions are linked to all AORs on LPAR 1 and LPAR 2.
  • Several AORs. These regions are linked to, from TORs on LPAR 1 and LPAR 2.

Both sets of TORs are defined with the same z/OS® Communications Server generic resource. This means that, when the TORs are shut down on one LPAR, the work should transfer to the TORs on the second LPAR. CICSPlex SM can pass work that comes in to a TOR to any available AOR. This means that, each TOR connects to every AOR.

As shown in Table 1, this example shows CICS TS 5.5 and CICSPlex SM 5.5 as the current release, and CICS TS beta and CICSPlex SM beta as the target release, but the upgrade information here is equally applicable when you upgrade from any lower release to a higher release of your choice.

Table 1. Release level upgrade overview for the example CICSplex
LPAR Region Initial or current release Target release
LPAR 1 MP CMAS

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 1 Non-MP CMAS

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 1 WUI

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 1 TORs

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 1 AORs

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 2 Non-MP CMAS

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 2 TORs

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta
LPAR 2 AORs

CICS TS 5.5

CICSPlex SM 5.5

CICS TS beta

CICSPlex SM beta

Upgrade workflow

In this example, the CICSplex is upgraded as follows:
  1. Upgrade the MP CMAS.
  2. Upgrade the CICSPlex SM WUI server, which contains the CMCI.
  3. Upgrade each LPAR, one at a time.

    In this example, the upgrade for each LPAR starts with upgrading the AORs first, followed by the TORs. However, whether you upgrade the AORs followed by the TORs, or upgrade the TORs followed by the AORs varies according to your own environment and application setup needs.

    So, for this example, each LPAR is upgraded in the following order:
    1. Upgrade each set of AORs.
    2. Upgrade each set of TORs.
    3. Upgrade the non-MP CMAS running on the LPAR.

    One LPAR is upgraded first, then the other.

Tip: Upgrade TORs first? Or AORs first?

If AORs are upgraded before TORs, the capacity to process workload in this LPAR is reduced during the upgrade of AORs while all TORs are fully functioning to receive and route work.

If TORs are upgraded before AORs, TORs at the latest level can route work to AORs at a lower level.

Plan your upgrade based on your workload and configuration.

Upgrading LPAR 1 followed by LPAR 2 works well with this example’s setup and workload combination. However, this is not the only approach that you might consider when doing your own upgrading. The approach that you take should be determined by your own circumstances, setup, and workload needs.

Procedure

Assuming the upgrade workflow for the example CICSplex, the steps for the solution are as follows:

Step 1. Back up any data sets that you need to retain

Before you start any upgrade, you should back up any data sets that you need to retain. These data sets can include CICS system definition data sets (CSDs) and exported WUI repositories.

Step 2. Upgrade the MP CMAS and the WUI

If you are not running a WUI server, ignore the steps that refer to it.

  1. Shut down the maintenance point CMAS (MP CMAS). For more details, see Shutting down a CMAS. The CICS workload continues to run, even without the MP CMAS.
  2. For the MP CMAS, upgrade both CICS TS and CICSPlex SM to the target release level (in this example, CICS TS beta and CICSPlex SM beta). Restart the MP CMAS.
  3. If you have a WUI, shut down the WUI server and upgrade the WUI region to the target release level (in this example, CICS TS beta and CICSPlex SM beta). Restart the WUI.
Result
In the CICSPlex SM WUI or CICS Explorer®, you can see the MP CMAS and the CICSPlex SM WUI at the level of CICS TS beta and CICSPlex SM beta.

Step 3. Upgrade the first LPAR

  1. For each AOR:
    1. Quiesce the AOR as a workload target. Check that all work that was running in that region is completed. For details, see Quiescing a target region in an active workload.
    2. When there are no running tasks, shut down the AOR.
    3. Upgrade the AOR to CICS TS beta and CICSPlex SM beta. Do not restart the upgraded AOR.
  2. For each TOR:
    1. Deregister the TOR as a z/OS Communications Server generic resource by using the SET VTAM DEREGISTERED command. Close the communication or connection between CICS and z/OS Communications Server by using the SET VTAM CLOSED command, making the TOR unavailable to incoming work. For details, see Removing a TOR from a generic resource.

      z/OS Communications Server is previously known as VTAM®.

    2. When no terminals are connected for the TOR and when all work running in the TOR is completed, shut down the TOR.
    3. Upgrade the TOR to CICS TS beta and CICSPlex SM beta. Do not restart the upgraded TOR.
  3. Shut down and upgrade any remaining CMAS.
  4. Restart all CMASs. For details, see Restarting a CMAS.
  5. When the CMASs are active, restart all AORs.
  6. Restart all TORs.
Result
Work is coming into the routing regions on both LPARs. It is routed to target regions in both LPARs. You can now upgrade the second LPAR while workload continues to run in the first LPAR.

Step 4. Upgrade the second LPAR

When work is flowing again in the first LPAR, you can upgrade the second LPAR.

  1. For each AOR:
    1. Quiesce the AOR as a workload target. Check that all work that was running in that region is completed. For details, see Quiescing a target region in an active workload.
    2. When there are no running tasks, shut down the AOR.
    3. Upgrade the AOR to CICS TS beta and CICSPlex SM beta. Do not restart the upgraded AOR.
  2. For each TOR:
    1. Deregister the TOR as a z/OS Communications Server generic resource by using the SET VTAM DEREGISTERED command. Close the communication or connection between CICS and z/OS Communications Server by using the SET VTAM CLOSED command, making the TOR unavailable to incoming work. For details, see Removing a TOR from a generic resource.

      z/OS Communications Server is previously known as VTAM.

    2. When no terminals are connected for the TOR and when all work running in the TOR is completed, shut down the TOR.
    3. Upgrade the TOR to CICS TS beta and CICSPlex SM beta. Do not restart the upgraded TOR.
  3. Shut down and upgrade any remaining CMAS.
  4. Restart all CMASs. For details, see Restarting a CMAS.
  5. When the CMASs are active, restart all AORs.
  6. Restart all TORs.
Result
Work is coming into the routing regions on both LPARs. It is routed to target regions in both LPARs.