Resiliency with Tessell DBaaS

Tessell is a fully managed database service for PostgreSQL, MySQL, Oracle, and SQL Server, built on AWS and Azure with a 99.99% SLA backed by a 24/7 SRE team. This technical reference guide explains how Tessell handles planned maintenance and unplanned outages across single-zone, high availability, and disaster recovery deployments. It covers the architecture, RPO and RTO characteristics, and trade-offs of each tier, along with the application-side practices needed to make availability work end to end. The guide is structured as a progressive reference, where each architecture builds on the capabilities of the previous one.

What is inside

• A breakdown of planned downtime events, including configuration updates, vertical scaling, database flag changes, and maintenance windows with sub-60-second service interruptions

• How Tessell backups work across automated and on-demand snapshots, with retention configurable up to 35 days and point-in-time recovery using transaction logs

• The Tessell High Availability configuration across primary and standby zones, including synchronous replication, automatic failover, and zero RPO for instance or zone failures

• Read replica patterns for workload offloading and improved RPO and RTO, covering same-zone, cross-zone, and cross-region replica options

• The cross-region disaster recovery architecture for handling full regional outages, including the manual promotion steps and failback considerations

• Application-side requirements for HA deployments, covering connection pooling, exponential backoff with retry logic, and graceful degradation under load

Who is this for

This guide is written for DBAs, database architects, and platform engineers responsible for production database availability on AWS or Azure. It walks through the resiliency tiers available in Tessell DBaaS and the RPO and RTO each one delivers, so teams can match an architecture to their actual business continuity requirements. Use it to match a resiliency tier to your business continuity requirements. Pair it with product documentation for configuration details.