Provide for new device installations

Description: The hardware configuration of your processors and I/O devices determines how many devices you can attach to your system. z/OS supports attachment of up to 65,280 devices, each with up to eight access paths.

Element or feature:

Multiple.

When change was introduced:

General migration action not tied to a specific release.

Applies to migration from:

z/OS V1R13 and z/OS V1R12.

Timing:

Anytime.

Is the migration action required?

Yes, if you are going to use new devices with z/OS V2R1 and later.

Target system hardware requirements:

Dependent upon the new devices used.

Target system software requirements:

None.

Other system (coexistence or fallback) requirements:

None.

Restrictions:

None.

System impacts:

None.

Related IBM® Health Checker for z/OS® check:

None.

Steps to take: The following are general considerations related to I/O device support.

Attaching devices through HCD. You can define, or attach, new devices to your system through the interactive panels of the Hardware Configuration Definition (HCD) base element. HCD has dynamic I/O capabilities, changing hardware definitions without the need for an IPL or hard power-on reset.
Any time you make changes to your I/O configuration, you need to use HCD to modify your system's I/O definition file (IODF). You should also update the input/output configuration data set (IOCDS) when you run HCD to ensure that the configuration information is consistent across the software and microcode.
Operating modes. Most devices attached to z/OS operate in full function mode, that is, all features on the device are compatible with, and usable on, the operating system. Some of these features include:
- For DASD devices: dynamic path reconnection, extended count-key-data operation, and caching and cache-related facilities
- For tape devices: cartridge stack loading and data compaction
Some devices also operate in compatibility mode, which allows you to simulate the function of another device or model. Compatibility mode causes the device to function like a different device of the same type, ignoring some or all of the additional features the device might have. This allows you to migrate between devices with minimal impact on programs that have device dependencies.
UCB virtual storage constraint relief. Each device attached to the system has one or more UCBs associated with it. You have the option to define UCBs either above or below the 16 MB line by specifying the LOCANY parameter on the Hardware Configuration Definition (HCD) panel. The system programmer should review the contents of the link pack area (LPA) list to determine whether to remove or move libraries to gain virtual storage constraint relief.
Hardware maintenance. Some devices require a specific level of hardware maintenance to operate properly on a z/OS system. DFSMS software support for new hardware devices might also require the installation of PTFs.

Reference information:

For a summary of the most commonly-used I/O devices supported by z/OS that are also directly supported by DFSMS functions, see the topic about identifying I/O devices in z/OS Planning for Installation. If you have a question about support for a device that is not listed, contact your IBM representative.
For more information about HCD, see z/OS HCD Planning.
For information about working with IODFs, see z/OS HCD User's Guide.