Sysplex Distributor

Sysplex Distributor is the strategic IBM® solution for connection workload balancing across an IBM Parallel Sysplex®.

Sysplex Distributor is a component of IBM z/OS® Communications Server and provides TCP/IP load balancing across multiple LPARs. It can be combined with TCP/IP port sharing. Sysplex Distributor is a combination of the high availability features of distributed DVIPA and the workload optimization capabilities of WLM. The TCP/IP stacks can be configured to request workload information from WLM, enabling the distributing stack to forward those connections that are based on the workload of each of the target stacks. The WLM workload information is based on a comparison of available general CPU capacity for each target system.

z/OS Connect is a Java™ product, so it can use zSeries Integrated Information Processor (zIIP) capacity. You can configure the TCP/IP stacks to consider the available zIIP CPU capacity. You can also configure WLM-based forwarding based on server-specific workload.

High availability with preferred local connections

Where z/OS Connect makes an onward TCP/IP-based connection to another system, the z/OS Sysplex Distributor optimization capability can be applied to ensure that connections remain local to an LPAR whenever possible. This capability is enabled by use of the OPTLOCAL keyword on the VIPADISTRIBUTE statement in the associated VIPADYNAMIC block of the z/OS TCP/IP profile. For more information, see A launch icon to indicate a link opens a new tab or window. Sysplex distributor optimization with the OPTLOCAL keyword in the z/OS documentation.

This capability is useful in the following situations:
  • Preferring z/OS Connect to connect to a local CICS® region (over IPIC) by using the CICS service provider, but failing-over to a CICS region on another LPAR when no local peer region is available. Each peer CICS region uses a common listener port that is defined to z/OS Communications Server as shared, and specifying the OPTLOCAL keyword.
  • Preferring z/OS Connect to connect to a local IMS Connect instance by using the IMS mobile service provider, but failing-over to an IMS Connect instance on another LPAR when no local instance is available. Each peer IMS Connect instance uses a common listener port that is defined to z/OS Communications Server as shared, and specifying the OPTLOCAL keyword.
  • Preferring z/OS Connect to connect to a local Db2 server that provides the Db2 REST service by using the REST client service provider, but failing-over to a Db2 server on another LPAR when no local Db2 server that provides the Db2 REST service is available. Each Db2 server that provides the Db2 REST service uses a common listener port that is defined to z/OS Communications Server as shared, and specifying the OPTLOCAL keyword.
  • Preferring to connect to a z/OS Connect Server in the local LPAR for an application by using the API requester, but failing-over to a z/OS Connect Server in another LPAR when no local z/OS Connect Server that is configured with the same API requester is available. Each peer z/OS Connect Server users a common listener port that is defined to z/OS Communications Server as shared, specifying the OPTLOCAL keyword.

In each case, z/OS Connect relies upon facilities of the z/OS Sysplex Distributor. Specifically, the distributed VIPA keyword, OPTLOCAL, expresses the preference to keep connections within the local LPAR when possible.