Comparison
Active-passivevsWarm standby
Active-passive
the second site sits there costing money and serving nothing, and the day you need it you find out which four things were never replicated.
Keeping a secondary location ready but idle, promoted only on failure. It is simpler than active-active because there is one writer, and its weakness is exactly that it is never exercised, so its readiness is a belief rather than an observation. Regular, scheduled failovers are the only thing that turns it from a slide into a capability.
Full entry →Warm standby
a scaled-down copy runs continuously with the data replicating, and recovery is a scale-up rather than a build-out.
Keeping a smaller but live copy of the environment running, ready to be scaled up on failure. It sits between a cold rebuild from code, which is cheap and slow, and full active-active, which is expensive and instant, and it is where most disaster recovery designs land. Its recovery time is dominated by whatever cannot be pre-warmed — caches, connection pools, scaling limits you have never hit in that region.
Full entry →