How do I use IBM's Hardware Configuration and Definition (HCD) dialogs to define the Virtual Devices and Esoterics?

Products

• Vtape Virtual Tape System

Issue/Introduction

How do I use IBM's Hardware Configuration and Definition (HCD) dialogs to define the Virtual Devices and Esoterics of Vtape?

Environment

Release: 12.6
Component: Vtape

Resolution

Defining the Virtual Devices and Esoterics

Prior to using IBM's Hardware Configuration and Definition (HCD) dialogs to define the Virtual Devices and Esoterics, you will need to understand the device type of the Virtual Devices and how your applications will access those devices.

Device Type

The Vtape devices can only be defined as 3480 or 3490 devices. The device type chosen indicates to Vtape which channel command set to support for the Virtual Devices. The device type does not indicate whether or not compaction should or should not be used, the length of the virtual tape, or the storage capacity of the virtual tape.

We recommend the use of 3490, but it may be better to use 3480 under certain circumstances. For example, if you have 3490 devices and are a JES3 site, having two sets of 3490 devices in the same unit generic, one set defined to JES3 and one not defined to JES3 may require you to define Vtape as a Manual Tape Library to allow SMS to redirect mount requests to Vtape devices. If no 3480 devices are defined to JES3, defining the Virtual Devices as 3480s will avoid this problem.

Esoterics

Adding the Virtual Devices to existing unit esoterics like CART and TAPE allows your applications to access Virtual Devices without having to make JCL changes. Defining only a unique esoteric which contains just the Vtape Virtual Devices may be desirable for testing, but will force your applications to change their JCL to use those Virtual Devices. Defining both is recommended.

Primary and Alternate Virtual Device Ranges

If you purchased 16 drives, define two ranges of 16 drives each. One range will be the primary set and will be added to the VTAPE VTDRIVE parmlib member. The other range will be the alternate set and will be added to the VTDRALT parmlib member.

The primary set will be used for normal virtual tape processing. The alternate set will be used when a permanent failure of the primary set occurs that can only be cleared by an IPL. Instead of IPLing, Vtape will be stopped, the parmlib will be updated to use the VTDRALT member rather than the VTDRIVE member, and Vtape will be restarted.

This is just a safety precaution. In most cases, if a Virtual Device is fenced or boxed by the operating system, it can be restarted in Vtape and varied back online to the operating system without a problem.

Defining the Virtual Devices

If you are the system programmer responsible for maintaining the I/O Definition Files for your site, follow these steps to define the Virtual Devices:

1. Execute the HCD dialog.
   
   
2. Select option 1, Define, modify, or view configuration data.
   
   
3. Select option 5, I/O devices.
   
   
4. On the I/O Device List screen, review the list of defined devices to determine which ranges are available.
   
   
5. Press F11 to start the Add Device dialog.
   
   
6. Enter the first device number in the range to be defined, the number of devices in the range, and a device type of 3480 or 3490 and press ENTER. You will be automatically routed to the Define Device to Operating System Configuration screen.
   
   
7. Select the configuration the Virtual Devices will be defined to with an 's' and press ENTER.
   
   
8. On the Define Device Parameters/Features screen , make sure of the following settings and press ENTER:
   
   
   1. OFFLINE is set to NO.
      
      
   2. DYNAMIC is set to YES. c. AUTOSWITCH is set to NO.
      
      
   3. SHARABLE is set to NO.
      
      
   4. COMPACTION is set to YES.
      
      
9. On the Assign/Unassign Device to Esoteric screen, page down the list of defined esoterics and change the Assigned column value to YES for each esoteric the Virtual Devices should be added to. When all the required esoteric updates have been completed, press ENTER.
   
   
10. Select the next configuration the Virtual Devices should be added to and repeat steps 8 and 9 or press ENTER to return to the I/O Device List screen.
    
    
11. Press PF3 twice to return to the main HCD panel and perform the procedure again for the alternate set of Virtual Devices.

Once you have the necessary device ranges defined and added to the appropriate esoterics, the new IODF file can be dynamically activated.

Do not forget to update the IPL parmlib with the new IODF file or your new definitions will no longer be in affect after the next IPL.