Achieving Extreme Availability: An Introduction to Active-Active Replication with Assure MIMIX HA

Business Forces Driving the Need for Continuous Extreme Availability

While the pace of business continues to increase, tolerance for downtime decreases. If your systems aren’t continuously available, your customers have access to competitive goods and services with just a few clicks, and they may not come back. Global business partners demand access to applications and data around the clock, or they may also choose to do business with your competitors.  Meanwhile, strict regulations and service level agreements have been levied against businesses, threatening them with penalties for downtime or lost data. Today’s Information Technology professionals face extreme challenges to meet ever-increasing goals for systems availability and business resilience. If these forces are at work in your organization, this paper gives you the information you need to plan for meeting extreme availability challenges head on.

Any discussion of high availability or disaster recovery centers around two key metrics, Recovery Time Objective (RTO) and Recovery Point Objective (RPO). Recovery Time Objective measures the amount of time systems can be down, from the initial outage to the point where business applications are available to
users again. Recovery Point Objective (RPO) identifies how much data a business is able and willing to lose or recreate after an outage, measured in time. These are the top service level objectives to consider when designing any high availability or disaster recovery solution.

Organizations must routinely evaluate their RPO and RPO service level agreements (SLAs). Tolerance for data loss in most industries has gone towards zero. Where minutes of downtime were once accepted, the tolerable level of downtime today is also moving towards single-digit minutes or even seconds. Hardware mirroring solutions for IBM i offload the replication function to the storage subsystem and deliver unpredictable recovery times, ranging from minutes to many hours. Traditional software replication solutions for IBM i have delivered the most reliable RTOs in the industry, allowing recovery from unplanned outages in a matter of minutes.

This white paper explores the use of Active-Active replication with Assure MIMIX HA to virtually eliminate downtime and balance workloads. A clear understanding of the fundamental differences between traditional, positional replication and the keyed replication required for Active-Active environments is provided. Considerations for detecting and resolving the database collisions that may occur in an Active-Active configuration are discussed, and the steps toward building a solid collision resolution strategy are detailed.