IT Management

Automated Dynamic IO for MVS-Based Mainframes

6 Pages

In the old days, it wasn’t a big deal to take down an entire MVS-based mainframe to add new hardware devices. Users and management alike seemed to understand that periodic mainframe outages were necessary events. Today, expectations are much different. Uptime requirements of 99.99 percent (or higher) are now common.

Taking an outage to add a new hardware device simply isn’t an option. This article demonstrates how to use the Hardware Configuration Definition (HCD) application in conjunction with the Dynamic I/O Reconfiguration Management function to add new hardware devices to MVS-based mainframes without requiring an outage of your MVS system(s). A technique called Automated Dynamic I/O also will be illustrated as a way to reduce the complexity and errors associated with performing dynamic I/O modifications.

Methods for Adding a New Device

Adding a new device to an MVS system hasn’t changed much over the years. You must define the device to the hardware, define the device to the software, and then activate these two changes. The difference between the Dynamic I/O method and non-Dynamic method is the process used to activate the changes. The Automated Dynamic I/O method builds upon the Dynamic I/O method by automating the updating of the HMC RESET profile to point to the correct IOCDS and also automates the updating of the LOADxx member to point to the correct IODF file.

Adding a device without the

Dynamic I/O Reconfiguration Management function requires the systems programmer to:

  1. Create a new IOCDS, using HCD, to define the device to the hardware.
  2. Create a new IODF file, using HCD, to define the device to MVS.
  3. Modify the LOADxx member to point to the new IODF.
  4. Modify the RESET HMC profile to point to the new IOCDS.
  5. Perform a POR.
  6. IPL the MVS image.

To add a device with Dynamic I/O, the fundamentals are the same, but the implementation methods are a bit different. Notice that neither a POR nor an IPL are required using the Dynamic I/O method:

To add a device with Dynamic I/O:

  1. Create a new IOCDS, using HCD, to define the device to the hardware.
  2. Create a new IODF file, using HCD, to define the device to MVS.
  3. Activate the software portion of the configuration using the ACTIVATE SOFT command.
  4. Activate the hardware portion of the configuration using the ACTIVATE command.
  5. Modify the LOADxx member to point to the new IODF.
  6. Modify the RESET HMC profile to point to the new IOCDS.

The new device is added after Step 4. Steps 5 and 6 are housekeeping steps and are often overlooked, causing problems later (i.e., a POR or IPL backs out the added device).

Adding a device using the Automated Dynamic I/O method is almost identical to the Dynamic I/O method, but the systems programmer isn’t required to update the RESET profile or the LOADxx member.

6 Pages