Dynamic enablement of zHyperWrite enhancement

In IMS 15.5, dynamic enablement of zHyperWrite enhancement provides a new parameter, ZHYPERWRITE, to the UPDATE IMS SET(LCLPARM) command to allow users to dynamically enable or disable IBM® zHyperWrite for the online log data sets (OLDS) and write-ahead log data set (WADS). Install APAR PH02149 (PTF UI61325) to enable this enhancement.

Previously, you could only use the ZHYPERWRITE parameter in the LOGGER section of the DFSDFxxx member to enable or disable the use of zHyperWrite. Furthermore, you had to restart IMS for the ZHYPERWRITE parameter to take effect. This enhancement provides a new optional keyword, ZHYPERWRITE, in the UPDATE IMS SET(LCLPARM) command. You can use the ZHYPERWRITE keyword of the UPDATE IMS SET(LCLPARM) command to dynamically enable or disable zHyperWrite for OLDS or WADS without restarting the IMS system.

Unlike using ZHYPERWRITE in the LOGGER section of the DFSDFxxx member, any change specified by using the ZHYPERWRITE parameter in the UPDATE IMS SET(LCLPARM) command is not saved if you restart IMS.

If you want the zHyperWrite changes to persist across a restart, update the ZHYPERWRITE parameter in the LOGGER section of DFSDFxxx and then issue the UPDATE IMS SET(LCLPARM(ZHYPERWRITE()) command. In this way, if IMS is restarted, the updated zHyperWrite value is saved and effective.

Coexistence considerations

If the UPDATE IMS SET(LCLPARM(ZHYPERWRITE)) command is routed to an IMS that does not support the command, the ZHYPERWRITE parameter is ignored.

Changes to commands

A new keyword, ZHYPERWRITE, is added to the UPDATE IMS SET(LCLPARM) command.

For a list of the commands that are new or changed for this enhancement see the IMS commands row in the table in Documentation changes.

Requirements

The primary and secondary data set volumes must be in a Metro Mirror relationship managed by HyperSwap®. To enable zHyperWrite for the OLDS, DFSMS APAR OA51385 must be installed and the OLDS must be defined as extended format data sets.

The UPDATE IMS command requires the Common Service Layer (CSL) with the Structured Call Interface (SCI) and the Operations Manager (OM) available. This command must be issued through the OM API because it is a type-2 command. The command response is returned through the OM API and is embedded in XML tags. You can issue this command in the following environments:
  • DB/DC
  • DBCTL
  • DCCTL

Restrictions

If you issue the UPDATE IMS SET(LCLPARM(ZHYPERWRITE())) command to enable or disable zHyperWrite for the OLDS, zHyperWrite is enabled or disabled for subsequent OLDS that IMS opens, but not for the OLDS that are currently open. To start or stop using zHyperWrite immediately, issue the /SWITCH OLDS command twice.

If you issue the UPDATE IMS SET(LCLPARM(ZHYPERWRITE())) command to enable or disable zHyperWrite for the WADS, zHyperWrite is enabled or disabled the next time IMS writes to the current WADS.

Documentation changes

The following table lists the publications that contain new or changed topics for the dynamic enablement of zHyperWrite enhancement. Publications that are not impacted by this enhancement are not included in the table.

Table 1. Links to topics that have new or changed content for this enhancement
Publication Links to topics
Release planning
System definition
System administration
IMS commands