Estimator program for estimating the availability of an application program that runs in a cluster of at least two computers

A program storage device embodying an estimator program that performs method steps for estimating the availability of an application program that runs on any computer in a cluster of at least two computers;

• said method including the steps of:
• receiving input parameters which include multiple downtime periods for each computer in said cluster that occur at respective frequencies due to various downtime period sources, and include an application failover time period for switching the running of said application program from any one of said computers to another;
• generating from said input parameters, a single computer virtual downtime period and a single computer virtual time between stops and a single computer virtual stoppage rate;
• estimating a first annual stoppage time for said application program, due solely to concurrent stoppage of all of said computers, as a function of the ratio of said single computer virtual downtime period over said single computer virtual time between stops;
• estimating a second annual stoppage time for said application program, due solely to switching the running of said application program from one computer to another as a function of said single virtual stoppage rate and said application failover time period;
• and,
• determining said availability of said application program on said cluster from the sum of said first and second annual stoppage times.