Azure Cache for Redis
Every SKU of this service (Basic, Standard, Premium) is retiring on September 30, 2028, in favor of Azure Managed Redis — any resiliency plan built today should target the replacement service. Geo-replication here has no guaranteed recovery point.
Basic tier
Single node, no replica, no SLA.
- Replication
- None
- RPO
- N/A — cache data loss on node failure is expected by design
- RTO
- No guarantee
- Failover trigger
- N/A
- Relative cost
- No extra cost
Cheapest tier — the baseline this whole service is priced against.
Shows Unknown at every tier — there's no fixed RPO/RTO for this option; it depends entirely on an architecture you'd have to design and build.
Premium tier with zone redundancy
Replicas spread across zones with platform-managed primary/replica failover.
- Replication
- Asynchronous
- RPO
- Near-zero but not guaranteed — Redis replication is asynchronous even within a region
- RTO
- Seconds — automatic platform-managed failover
- Failover trigger
- Automatic
- Relative cost
- Moderate cost premium
Requires Premium tier (pricier than Basic/Standard) plus the replica nodes zone redundancy spreads across.
The 99.95% figure is an uptime SLA, not a data-loss guarantee — it says nothing about the RPO. Failover itself is automatic and fast, but Microsoft commits to neither a specific recovery point nor zero data loss for it.
Can reach at most Risk, never Pass — failover is automatic, but the RPO/RTO figures aren't backed by a Microsoft SLA or explicit commitment.
Passive geo-replication (Premium)
Active-passive link between two Premium caches, usually in different regions. Continuous asynchronous replication, but Microsoft's own documentation states no recovery point is guaranteed, and persistence is disabled entirely while the link is active.
- Replication
- Asynchronous
- RPO
- Not guaranteed — Microsoft explicitly states 'no recovery point is guaranteed' for unlinked/failed-over data
- RTO
- A few minutes once manually triggered
- Failover trigger
- Manual (customer-triggered)
- Relative cost
- High cost premium
A second full Premium-tier cache instance, kept running and billed continuously even while passive.
Shows Unknown at every tier — there's no fixed RPO/RTO for this option; it depends entirely on an architecture you'd have to design and build.
Gotchas
The whole service is being retired — September 30, 2028
Microsoft has set a firm retirement date: all Azure Cache for Redis Basic, Standard, and Premium instances retire on September 30, 2028, and remaining instances are disabled starting October 1, 2028. Any resiliency documentation, architecture diagram, or tier-mapping exercise built against Azure Cache for Redis today needs a migration plan to Azure Managed Redis, not just an awareness that retirement is coming someday.
Geo-replication explicitly has no guaranteed recovery point
This isn't 'typically low RPO' language — Microsoft's own docs state plainly that no recovery point is guaranteed after an unlink/failover, and persistence (disk-backed durability) is disabled entirely while geo-replication is active.
Treat cache as rebuildable, not as a system of record
For most architectures, the right DR answer for a cache isn't geo-replication at all — it's accepting the cache is rebuildable from the actual source of truth, and sizing warm-up time into your RTO instead of engineering cache-layer DR.