ITSS 4370 Availability and Reliability

Incident

Unplanned interruption to an IT service or an unplanned reduction in its quality

Problem

Unknown underlying cause of one or more incidents

Availability

the process of optimizing the readiness of production systems by accurately measuring, analyzing, and reducing outages to those production systems

Uptime is geared toward

suppliers and generally pertains to specific components of the system

root causes of slow response

performance and tuning issues

The root causes of downtime

usually involve one or multiple component failures

High Availability focuses

on eliminating system outages

System outages are eliminated by

designing and utilizing redundancy in the environment

Methods for Measuring Availability

• traditonal

  • alternative

Traditional method

%Uptime = (Actual Uptime) / (Scheduled Uptime)

alternative methods for measuring availability

Measure uptime in terms meaningful to users

Quantify amount of downtime

Performance and Tuning

a methodology to maximize throughput and minimize response times of batch jobs, online transactions, and Internet activities

The two performance items that most IT customer

want the most are

maximum throughput

- minimal response times.

Major performance issues for

Internet applications

Logon time

Link response time

Content response time

Video response time

Audio response time