Interview › Resume & Behavioral
Walk me through the Redis-to-Valkey migration: why migrate, what was your plan, and what could have gone wrong?
Resume & Behavioral · Basic level
Answer
I would describe this as a compatibility and reliability migration, not simply swapping an endpoint. I would inventory every service using Redis-style functionality, validate Valkey compatibility, test failover and performance, migrate low-risk workloads first, and then move critical traffic through a controlled canary. The major risks are client incompatibility, latency regression, persistence or replication differences, data loss for stateful usage, and unclear rollback. My focus would be to make each risk visible before production cutover.
Technical explanation
A safe migration starts with inventory: service owner, commands used, client library, data criticality, TTL behavior, persistence needs, traffic, and peak load.
Cache-only use cases are easier to rollback than persistent state use cases; the rollback strategy depends on write behavior and data consistency requirements.
Success criteria should include application error rate, p95/p99 latency, hit rate, memory, evictions, connection count, failover behavior, and rollback validation.
Hands-on example
1. Build a migration tracker for all services and classify each as low, medium, or high risk.
2. Deploy Valkey in staging, run integration tests, performance tests, and failover tests with production-like settings.
3. Move one low-risk service by configuration, watch metrics, and keep the old Redis endpoint ready for rollback.
4. After the validation window passes, migrate higher-risk services in waves and record lessons in a reusable playbook.
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