A Modern Look at Reliability, Availability, and Scalability

Computer manufacturers often stress performance and availability in their marketing literature. Yet, reliability (R), availability (A), and scalability (S) are the three pillars that support mission-critical applications, and they all need appropriate attention.

The elements of RAS are complimentary measures, but they are not the same. This article looks at the three pillars from a modern perspective.

RPO and RTO vs. IPO and ITO

Companies already know that they need to specify their datacenters’ availability in terms of their:

• Recovery Point Objective (RPO) – the amount of data they may lose as the result of a system failure,
• Recovery Time Objective (RTO) – the amount of time required to recover from a system failure.

We argue that companies also need to know their:

• Integrity Point Objective (IPO) – the amount of corrupted data that the application, company, and users can tolerate,
• Integrity Time Objective (ITO) – the amount of time that the application, company, and users can tolerate corrupted data before the problem is resolved.

Article (Part 1):
A Modern Look at Reliability, Availability, and Scalability – Part 1

Inside:

• The Three Pillars of Mission-Critical Computing
  • Figure 1 – RAS: The Three Pillars of Mission-Critical Computing
  • Figure 2 – RPO/RTO and the Similar Relationship that Exists for IPO/ITO
• Hardware Is Not the Answer
• What’s Next