Availability 101

There are many aspects to availability and it’s important to understand how the aspects fit together to architect the right solution for your organization.

Distinguishing High Availability vs. Disaster Recovery vs. Backup

Before examining solutions for availability, it’s important to understand which type of availability we need and the architectural decisions and technologies that will be leveraged. Note that we often don’t pick; we often need all three of the types of resiliency I am going to cover. You will hear about RPO and RTO when discussing backups, high availability, and disaster recovery, which relate to:

Recovery Point Objective (RPO) The recovery point in the event of an incident—i.e., how much data can be lost, e.g., 30 minutes (for unplanned incidents; planned incidents ideally would suffer no data loss)

Recovery Time Objective (RTO) The amount of time it takes to activate the resiliency and be up and running—that is...