Database high availability
Keep databases usable through failure, failover and recovery
Design a switchable, verifiable and maintainable database availability path around nodes, replication, failure boundaries, business connections, backup, recovery and operations monitoring.
01 / Nodes and boundaries
Make database nodes, business connections and failure domains explicit
Database high availability is not simply adding another server. Define application entry points, how data synchronizes, which components share a failure domain and what the business sees during node, network or storage faults.
The architecture should answer who connects, who carries the workload, who synchronizes and who takes over instead of listing database software and hardware.
- 01Business entry
Confirm connection strings, proxies, load balancing, DNS and post-failover access paths.
- 02Synchronization
Define synchronization mode, lag, replication state and protection actions during exceptions.
- 03Failure boundary
Separate node, host, rack, network, storage and room-level failures.
02 / Replication and protection
Design replication together with backup and recovery
Availability keeps service access continuous; it is not the same as historical data protection. Real-time replication, independent backup, offline or remote copies, recovery targets and checks belong in one protection boundary.
When deletion, logical corruption or a bad change occurs, switching to another node may carry the problem with it; an independent recovery path must be prepared.
- 01Availability replication
Track synchronization, lag, quorum, failure detection and failover conditions.
- 02Independent backup
Keep a backup repository, retention and recovery access independent from production nodes.
- 03Capacity and recovery
Assess data growth, logs, backup windows, recovery space and validation time together.
03 / Failover
Use controlled failover to verify that business connections really recover
Failover validation starts with connections, transactions, replication, application reconnects and data consistency. It is not enough for a node to show “online”; business requests must reach the new active node as intended.
During a maintenance window, simulate node, link or storage faults and record detection, switch time, business impact, alerts and rollback conditions.
- 01Detection and decision
Define the trigger signals and how to avoid false decisions and split brain.
- 02Application reconnect
Verify connection entry points, pools, transactions, caches and interfaces continue working.
- 03Business acceptance
Have the business check critical queries, writes, reports and upstream/downstream interfaces.
04 / Operations and handover
Make replication, capacity, alerts and exercises part of daily operations
After go-live, monitor replication lag, node health, log growth, backup completion, capacity headroom and alert handling. Handover records should tell operators what to watch, when to act and who escalates.
Put routine checks, exercises, configuration backup, version changes and recovery retests into one maintenance plan so availability does not degrade over time.
- 01State and capacity
Track nodes, replication, logs, storage and growth trends.
- 02Alerts and ownership
Assign owners and response times for lag, failures, low space and connection anomalies.
- 03Records and retests
Keep topology, configuration, failover records, exercise results and the next retest plan.
Next step
Start with the current environment, priorities and recovery requirements
Share the current equipment, dependencies, site conditions, data change, operating issue or delivery window so the service boundary and practical path can be reviewed.