Azure Managed Redis does not show "maxmemory" in the result of the "info" command

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Azure Managed Redis does not show "maxmemory" in the result of the "info" command

Mathieu Longtin 116 Microsoft Employee

Azure Cache for Redis and open source Redis both return the value for "maxmemory" when calling the "info" command. But Azure Managed Redis does not. It also doesn't show any of the "_perc" values that show the percentage of memory used.

Is there anyway for a client to figure what the maximum size of an "Azure Managed Redis" instance?

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Answer 1

Swapnesh Panchal 1,380 Microsoft External Staff Moderator

Hi Mathieu Longtin ,
Thanks for contacting to Microsoft QA.
Azure managed redis doesn’t expose maxmemory via INFO, and CONFIG is blocked. the service enforces the memory ceiling outside of redis (container/host quota), so there’s no redis-protocol call a client can use to read “maximum size.”
so you can’t get max from INFO. get capacity from the resource’s sku (portal/arm/cli), derive total by shards, and monitor usage with azure monitor.

way to know the max:

treat the management plane as source of truth. the sku you provisioned defines capacity.
get it from portal/arm/cli/sdk, then map sku → memory per shard from the sizing table and multiply by shard count (that’s your total data memory, before overhead/replicas).
- classic cache: az redis show -g <rg> -n <name> --query "sku"
- enterprise/managed variants: az redisenterprise show -g <rg> -n <name> --query "sku"
if you need a percentage at runtime, compute it yourself: used_memory / sku_capacity. azure managed redis doesn’t return the _perc fields.

monitor in production:

rely on azure monitor metrics (e.g., used memory / rss) or INFO memory’s used_memory to track growth.
alert around 75–80% of sku capacity to leave headroom for fragmentation, replication, and service overhead—evictions and latency usually show up before 100%.

Abhisek Mishra 1,020 Reputation points Microsoft External Staff Moderator

2025-10-13T06:33:22.3+00:00

Hi Mathieu Longtin,

I hope you had a chance to review the information shared earlier, and I hope this information has been helpful! If you still have questions, please let us know what is needed in the comments so the question can be answered.
Mathieu Longtin 116 Reputation points Microsoft Employee

2025-10-13T22:16:01.1133333+00:00

Azure Cache for Redis also manages the maximum memory from outside, but the information is still available read-only. I don't understand why it's hidden in Azure Managed Redis.

Also, why is there a single DB available in Azure Managed Redis? This is a useful feature.

There is no mention of either of those shortcomings in the documentation, yet they are notable differences from the normal Redis experience.
Swapnesh Panchal 1,380 Reputation points Microsoft External Staff Moderator

2025-10-16T16:02:16.1066667+00:00
Hi Mathieu Longtin,

Thanks for the follow-up.

On maxmemory in INFO: Azure Managed Redis enforces memory limits from the management plane (your SKU and shard layout). The service doesn’t expose that limit over the Redis protocol, so INFO won’t include maxmemory. Treat the SKU as the source of truth for capacity, and monitor growth with Azure Monitor. If you need a percentage at runtime, compute it yourself, e.g., used_memory / total_data_capacity (where total capacity comes from per-shard capacity × shard count, before overhead/replicas).

Why only a single database: Managed Redis is built on a clustered architecture. Redis Cluster uses only database 0 (no SELECT across DBs), so Managed Redis exposes a single logical DB per instance.

Operational guidance:

Get the “max” from the provisioned SKU/shard config, not from INFO.

Set alerts on memory metrics (used memory / RSS) in Azure Monitor around 75–80% to leave headroom.

Some config/inspection commands are intentionally blocked in managed offerings; rely on the control plane plus metrics for capacity and scaling.
Mathieu Longtin 116 Reputation points Microsoft Employee

2025-10-16T16:26:40.51+00:00

But why is maxmemory not exposed? Azure Cache for Redis manages to expose it.

This means the monitoring requires Reader role on the service. Before, it could work with just access to Redis server.
Swapnesh Panchal 1,380 Reputation points Microsoft External Staff Moderator

2025-10-16T22:01:18.19+00:00
it’s by design. Azure Managed Redis runs Redis Enterprise, which doesn’t expose a single maxmemory via INFO/CONFIG because memory is managed per shard/database; the meaningful limits live in the management plane, not the data-plane. ([Redis][1])

What this means for you

You won’t get maxmemory (or the *_perc fields) from a Redis connection. Use Azure Monitor (management plane) to read memory usage like usedmemory.

You don’t need full Reader. Grant Monitoring Reader (or a custom role with Microsoft.Insights/metrics/read) scoped to that cache to fetch metrics without broader access.

Quick CLI example

az monitor metrics list \ --resource <RESOURCE_ID> \ --metric usedmemory \ --interval PT1M \ --aggregation Average

(Grab metric names from the Redis Enterprise metrics reference.) ([Microsoft Learn][4])

If you need an “effective cap” for % calculations

Pull the SKU from the resource and map it to the tier’s memory size from the Managed Redis tiers/pricing tables, then account for overhead in your math.

Why Azure Cache for Redis looks different

The classic service is based on OSS Redis and surfaces memory knobs like maxmemory, so older agent-style monitoring could compute percentages purely from INFO. Managed Redis follows Redis Enterprise behavior, hence management-plane metrics/RBAC.

If you want, I can draft a tiny Bash/PowerShell snippet that pulls usedmemory and your SKU size and prints a simple utilization %.
Swapnesh Panchal 1,380 Reputation points Microsoft External Staff Moderator

2025-10-16T22:01:48.4266667+00:00

i mean “Azure Managed Redis” (not “Managed Redis tiers”) when i referring to SKU mapping.
Mathieu Longtin 116 Reputation points Microsoft Employee

2025-10-17T13:48:54.0833333+00:00

What other "by design" things are removed from standard Redis? This feature has been in Redis for at least 10 years, and it's not documented that it was removed.
Swapnesh Panchal 1,380 Reputation points Microsoft External Staff Moderator

2025-10-17T17:25:07.1933333+00:00

Thank you for raising this point. The behavior you observed is by design for Azure Managed Redis. Certain commands and settings, such as maxmemory in the INFO output, are intentionally not exposed because memory limits are enforced at the platform level rather than through Redis configuration. This approach ensures consistency, security, and operational stability.Please use the Azure management tools (Portal, CLI, or SDK) to retrieve the SKU details, which define the memory size. For monitoring, Azure Monitor metrics like Used Memory and Memory Utilization are recommended.
You can refer to Microsoft’s official documentation for more details:
https://learn.microsoft.com/en-us/azure/redis/overview
https://learn.microsoft.com/en-us/azure/redis/monitor-troubleshoot-faq
Swapnesh Panchal 1,380 Reputation points Microsoft External Staff Moderator

2025-10-18T06:21:18.6066667+00:00

Just checking in, if you have any questions or need clarification, feel free to let us know. We’d be happy to continue the conversation.

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Azure Managed Redis does not show "maxmemory" in the result of the "info" command

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