OpenVMS Boot Camp 2015
The OpenVMS Fast I/O Facility

Track: Programming

James Preciado, Principal, James J. Preciado, LLC

The OpenVMS Fast I/O facility is a set of three system services, available on OpenVMS Alpha and Integrity, that provide a mechanism for streamlining high volume input/output (i.e., read and write) requests. The Fast I/O Facility is not a replacement for the $QIO system service. It was developed as a $QIO alternative (for reads and writes), designed for speed, and is supported for interoperation with other OpenVMS I/O system services ($ASSIGN, $DASSGN, RTL socket routines, etc.). While originally developed for mass storage (disk and tape) devices, a lower degree of optimization can also be achieved for other OpenVMS devices. This session will provide a detailed analysis of the Fast I/O Facility. The mechanisms used to achieve I/O optimizations will be examined and contrasted with the $QIO system service. Detailed timings showing performance gains will be provided along with examples of the coding changes needed to use the Fast I/O Facility.

Experience Level