Technical data

Programming Features
5.7 Multipath System Services
• SET DEVICE device-name/PATH=path-description-string/[NO]ENABLE
• SHOW DEVICE/MULTIPATH device-name
In OpenVMS Version 7.3, the capability to return path information and allow you
to enable, disable, and switch specific I/O paths to any device is now implemented
in the following new system services:
• SYS$DEVICE_PATH_SCAN
This service returns path information for a given Multipath I/O device.
Each call to the service returns the name of one of the paths to the device.
A context argument is used to maintain continuity between calls. This
mechanism is similar to the one currently used for SYS$GETDVI.
• SYS$SET_DEVICE[W]
Use this service to switch the selected path that handles I/O to a device,
or to enable or disable a path for future use in the event of failover. When
switching a path, the path change is initiated at the time the request is made
by the system service.
The current functions of this service include forcing an immediate path switch
and enabling or disabling paths.
A synchronous version of this service, SYS$SET_DEVICEW, is also provided.
This service returns to the caller only after the path switch attempt has been
made. Should the path switch fail, an error condition is returned to the caller.
Currently, $SET_DEVICE allows only one valid item list entry.
For additional information, refer to the OpenVMS System Services Reference
Manual.
5.8 Multiprocess Debugging (Alpha)
For Version 7.3, debugger support for multiprocess programs has been extensively
overhauled. Problems have been corrected and the user interface has been
improved.
The multiprocess debugging enhancements include the following features:
• Greater control over individual process and groups of processes, including:
Execution of processes (or groups of processes)
Suspension of processes (or groups of processes)
Exiting processes (or groups of processes), with or without exit handler
execution
• Ability to create user-defined groups of processes
• Easier to start a multiprocess debugging session; the default configuration of
the kept debugger is for a multiprocess session
• Applications that use $HIBER WAIT (LIB$WAIT, $SCHDWK, and so on) can
now be debugged in a multiprocess debugging session
These enhancements make it much easier to debug multiprocess programs.
Programming Features 5–7