How to configure Azure Cache for Redis

This article describes the configurations available for your Azure Cache for Redis instances. This article also covers the default Redis server configuration for Azure Cache for Redis instances.

Configure Azure Cache for Redis settings

1. To create a cache, sign in to the Azure portal and select Create a resource.

   

2. On the Get Started page, type Azure Cache for Redis in the search box. Then, select Create.

   

3. On the New Redis Cache page, configure the settings for your cache.

   Setting	Choose a value	Description
   Subscription	Drop down and select your subscription.	The subscription under which to create this new Azure Cache for Redis instance.
   Resource group	Drop down and select a resource group, or select Create new and enter a new resource group name.	Name for the resource group in which to create your cache and other resources. By putting all your app resources in one resource group, you can easily manage or delete them together.
   DNS name	Enter a unique name.	The cache name must be a string between 1 and 63 characters that contain only numbers, letters, or hyphens. The name must start and end with a number or letter, and can't contain consecutive hyphens. Your cache instance's host name is <DNS name>.redis.cache.chinacloudapi.cn.
   Location	Drop down and select a location.	Select a region near other services that use your cache.
   Cache SKU	Drop down and select a SKU.	The SKU determines the size, performance, and features parameters that are available for the cache. For more information, see Azure Cache for Redis Overview.
   Cache size	Drop down and select a size of your cache	For more information, see Azure Cache for Redis Overview.

4. Select the Networking tab or select the Networking button at the bottom of the page.

5. In the Networking tab, select your connectivity method.

6. Select the Next: Advanced tab or select the Next: Advanced button on the bottom of the page to see the Advanced tab.

   

   • For Basic or Standard caches, toggle the selection for a non-TLS port. You can also select if you want to enable Microsoft Entra Authentication.
   • For a Premium cache, configure the settings for non-TLS port, clustering, managed identity, and data persistence. You can also select if you want to enable Microsoft Entra Authentication.

7. Select the Next: Tags tab or select the Next: Tags button at the bottom of the page.

8. Optionally, in the Tags tab, enter the name and value if you wish to categorize the resource.

9. Select Review + create. You're taken to the Review + create tab where Azure validates your configuration.

10. After the green Validation passed message appears, select Create.

It takes a while for a cache to create. You can monitor progress on the Azure Cache for Redis Overview page. When Status shows as Running, the cache is ready to use.

You can view and configure the following settings using the Resource Menu. The settings that you see depend on the tier of your cache.

• Overview
• Activity log
• Access control (IAM)
• Tags
• Diagnose and solve problems
• Events
• Settings
  • Authentication
  • Advanced settings
  • Scale
  • Cluster size
  • Data persistence
  • Identity
  • Schedule updates
  • Geo-replication
  • Virtual Network
  • Private Endpoint
  • Firewall
  • Properties
  • Locks
• Administration
  • Import data
  • Export data
  • Reboot
• Monitoring
• Automation
  • Tasks (preview)
  • Export template
• Support & troubleshooting settings
  • Resource health
  • New support request

Overview

The Overview section provides you with basic information about your cache, such as name, ports, pricing tier, and selected cache metrics.

Activity log

Select Activity log to view actions done to your cache. You can also use filtering to expand this view to include other resources. For more information on working with audit logs, see Audit operations with Resource Manager. For more information on monitoring the activity log, see Activity log.

Access control (IAM)

The Access control (IAM) section provides support for Azure role-based access control (Azure RBAC) in the Azure portal. This configuration helps organizations meet their access management requirements simply and precisely. For more information, see Azure role-based access control in the Azure portal.

Tags

The Tags section helps you organize your resources. For more information, see Using tags to organize your Azure resources.

Diagnose and solve problems

Select Diagnose and solve problems to be provided with common issues and strategies for resolving them.

Events

Select Events to add event subscriptions to your cache. Use events to build reactive, event-driven apps with the fully managed event routing service that is built into Azure.

The Event Grid helps you build automation into your cloud infrastructure, create serverless apps, and integrate across services and clouds. For more information, see What is Azure Event Grid.

Redis console

You can securely issue commands to your Azure Cache for Redis instances using the Redis Console, which is available in the Azure portal for Basic, Standard and Premium cache tiers.

To access the Redis Console, select Console tab in the working pane of Resource menu.

To issue commands against your cache instance, type the command you want into the console.

Using the Redis Console with a premium clustered cache

When using the Redis Console with a premium clustered cache, you can issue commands to a single shard of the cache. To issue a command to a specific shard, first connect to the shard you want by selecting it on the shard picker.

If you attempt to access a key that is stored in a different shard than the connected shard, you receive an error message similar to the following message:

shard1>get myKey
(error) MOVED 866 13.90.202.154:13000 (shard 0)
shard1>get myKey
(error) MOVED 866 13.90.202.154:13000 (shard 0)

In the previous example, shard 1 is the selected shard, but myKey is located in shard 0, as indicated by the (shard 0) portion of the error message. In this example, to access myKey, select shard 0 using the shard picker, and then issue the desired command.

Move your cache to a new subscription

You can move your cache to a new subscription by selecting Move.

For information on moving resources from one resource group to another, and from one subscription to another, see Move resources to new resource group or subscription.

Settings

The Settings section allows you to access and configure the following settings for your cache.

• Authentication
• Advanced settings
• Scale
• Cluster size
• Data persistence
• Schedule updates
• Geo-replication
• Private endpoint
• Virtual Network
• Firewall
• Properties
• Locks

Authentication

You have two options for authentication: access keys and Microsoft Entra Authentication.

Advanced settings

The following settings are configured on the Advanced settings on the left.

• Access Ports
• Memory policies
• Keyspace notifications (advanced settings)

Access Ports

By default, non-TLS/SSL access is disabled for new caches. To enable the non-TLS port, Select No for Allow access only via SSL on the Advanced settings on the left and then Select Save.

Memory policies

Use the Maxmemory policy, maxmemory-reserved, and maxfragmentationmemory-reserved settings from Advanced settings from the Resource menu on the left to configure the memory policies for the cache. When you create a cache, the values maxmemory-reserved and maxfragmentationmemory-reserved default to 10% of maxmemory, which is the cache size.

Maxmemory policy configures the eviction policy for the cache and allows you to choose from the following eviction policies:

• volatile-lru: The default eviction policy. It removes the least recently used key out of all the keys with an expiration set.
• allkeys-lru: Removes the least recently used key.
• volatile-random: Removes a random key that has an expiration set.
• allkeys-random: Removes a random key.
• volatile-ttl: Removes the key with the shortest time to live based on the expiration set for it.
• noeviction: No eviction policy. Returns an error message if you attempt to insert data.
• volatile-lfu: Evicts the least frequently used keys out of all keys with an expire field set.
• allkeys-lfu: Evicts the least frequently used keys out of all keys.

For more information about maxmemory policies, see Eviction policies.

The maxmemory-reserved setting configures the amount of memory in MB per instance in a cluster that is reserved for noncache operations, such as replication during failover. Setting this value allows you to have a more consistent Redis server experience when your load varies. This value should be set higher for workloads that write large amounts of data. When memory is reserved for such operations, it's unavailable for storage of cached data. The minimum and maximum values on the slider are 10% and 60%, shown in megabytes. You must set the value in that range.

The maxfragmentationmemory-reserved setting configures the amount of memory in MB per instance in a cluster that is reserved to accommodate for memory fragmentation. When you set this value, the Redis server experience is more consistent when the cache is full or close to full and the fragmentation ratio is high. When memory is reserved for such operations, it's unavailable for storage of cached data. The minimum and maximum values on the slider are 10% and 60%, shown in megabytes. You must set the value in that range.

When choosing a new memory reservation value (maxmemory-reserved or maxfragmentationmemory-reserved), consider how this change might affect a cache that is already running with large amounts of data in it. For instance, if you have a 53-GB cache with 49 GB of data, then change the reservation value to 8 GB, this change drops the max available memory for the system down to 45 GB. If either your current used_memory or your used_memory_rss values are higher than the new limit of 45 GB, then the system has to evict data until both used_memory and used_memory_rss are below 45 GB. Eviction can increase server load and memory fragmentation. For more information on cache metrics such as used_memory and used_memory_rss, see Create your own metrics.

Keyspace notifications (advanced settings)

Redis keyspace notifications are configured on the Advanced settings on the left. Keyspace notifications allow clients to receive notifications when certain events occur.

)

For more information, see Redis Keyspace Notifications. For sample code, see the KeySpaceNotifications.cs file in the Hello world sample.

Scale

Select Scale to view or change the pricing tier for your cache. For more information on scaling, see How to Scale Azure Cache for Redis.

Cluster Size

Select Cluster Size to change the cluster size for a running premium cache with clustering enabled.

To change the cluster size, use the slider or type a number between 1 and 10 in the Shard count text box. Then, select OK to save.

Data persistence

Select Data persistence to enable, disable, or configure data persistence for your premium cache. Azure Cache for Redis offers Redis persistence using either RDB persistence or AOF persistence.

For more information, see How to configure persistence for a Premium Azure Cache for Redis.

Identity

Use Identity to configure managed identities. Managed identities are a common tool used in Azure to help developers minimize the burden of managing secrets and sign-in information.

Presently, you can only use managed identities for storage. For more information, see Managed identity for storage.

Schedule updates

The Schedule updates section allows you to choose a maintenance window for Redis server updates for your cache.

To specify a maintenance window, check the days you want. Then, specify the maintenance window start hour for each day, and select OK. The maintenance window time is in UTC.

For more information and instructions, see Update channel and Schedule updates.

Geo-replication

Geo-replication, on the Resource menu, provides a mechanism for linking two Premium tier Azure Cache for Redis instances. One cache is named as the primary linked cache, and the other as the secondary linked cache. The secondary linked cache becomes read-only, and data written to the primary cache is replicated to the secondary linked cache. This functionality can be used to replicate a cache across Azure regions.

Virtual Network

The Virtual Network section allows you to configure the virtual network settings for your cache. Virtual networks are limited to Premium caches. For information on creating a premium cache with VNET support and updating its settings, see How to configure Virtual Network Support for a Premium Azure Cache for Redis.

Private endpoint

The Private Endpoint section allows you to configure the private endpoint settings for your cache. Private endpoint is supported on all cache tiers Basic, Standard, and Premium. We recommend using private endpoint instead of VNets. Private endpoints are easy to set up or remove, are supported on all tiers, and can connect your cache to multiple different VNets at once.

For more information, see Azure Cache for Redis with Azure Private Link.

Firewall

• Firewall rules configuration is available for all Basic, Standard, and Premium tiers.

Select Firewall to view and configure firewall rules for cache.

You can specify firewall rules with a start and end IP address range. When firewall rules are configured, only client connections from the specified IP address ranges can connect to the cache. When a firewall rule is saved, there's a short delay before the rule is effective. This delay is typically less than one minute.

Properties

Select Properties to view information about your cache, including the cache endpoint and ports.

Locks

The Locks section allows you to lock a subscription, resource group, or resource to prevent other users in your organization from accidentally deleting or modifying critical resources. For more information, see Lock resources with Azure Resource Manager.

Administration settings

The settings in the Administration section allow you to perform the following administrative tasks for your cache.

• Import data
• Export data
• Reboot

Import/Export

Import/Export is an Azure Cache for Redis data management operation that allows you to import and export data in the cache. You can import and export an Azure Cache for Redis Database (RDB) snapshot from a premium cache to a page blob in an Azure Storage Account. Use Import/Export to migrate between different Azure Cache for Redis instances or populate the cache with data before use.

You can use import with Redis-compatible RDB files from any Redis server running in any cloud or environment:

• including Redis running on Linux
• Windows
• any cloud provider such as Amazon Web Services and others

Importing data is an easy way to create a cache with prepopulated data. During the import process, Azure Cache for Redis loads the RDB files from Azure storage into memory, and then inserts the keys into the cache.

Export allows you to export the data stored in Azure Cache for Redis to Redis compatible RDB files. You can use this feature to move data from one Azure Cache for Redis instance to another or to another Redis server. During the export process, a temporary file is created on the VM that hosts the Azure Cache for Redis server instance. The temporary file is uploaded to the designated storage account. When the export operation completes with either a status of success or failure, the temporary file is deleted.

Reboot

The Reboot item allows you to reboot the nodes of your cache. This reboot capability enables you to test your application for resiliency if there's a failure of a cache node.

If you have a premium cache with clustering enabled, you can select which shards of the cache to reboot.

To reboot one or more nodes of your cache, select the desired nodes and select Reboot. If you have a premium cache with clustering enabled, select the shards to reboot, and then select Reboot. After a few minutes, the selected node(s) reboot, and are back online a few minutes later.

Monitoring

The Monitoring section allows you to configure diagnostics and monitoring for your Azure Cache for Redis instance.

• For more information on Azure Cache for Redis monitoring and diagnostics, see Monitor Azure Cache for Redis.
• For information on how to set up and use Azure Cache for Redis monitoring and diagnostics, see Monitor Azure Cache for Redis.

Insights

Use Insights to see groups of predefined tiles and charts to use as starting point for your cache metrics. For more information, see Insights.

Metrics

Select Metrics to create your own custom chart to track the metrics you want to see for your cache. For more information, see Create your own metrics.

Alerts

Select Alerts to configure alerts based on Azure Cache for Redis metrics. For more information, see Create alerts.

Diagnostic settings

By default, cache metrics in Azure Monitor are stored for 30 days and then deleted. To persist your cache metrics for longer than 30 days, select Diagnostics settings to configure the storage account used to store cache diagnostics.

Advisor recommendations

The Advisor recommendations displays recommendations for your cache. During normal operations, no recommendations are displayed.

If any conditions occur during the operations of your cache such as imminent changes, high memory usage, network bandwidth, or server load, an alert is displayed in the Overview of the Resource menu.

Further information can be found on the Recommendations in the working pane of the Azure portal.

You can monitor these metrics on the Monitoring section of the Resource menu.

Azure Cache for Redis metric	More information
Network bandwidth usage	Cache performance - available bandwidth
Connected clients	Default Redis server configuration - max clients
Server load	Redis Server Load
Memory usage	Cache performance - size

To upgrade your cache, select Upgrade now to change the pricing tier and scale your cache. For more information on choosing a pricing tier, see Choosing the right tier.

Workbooks

Organize your metrics into groups so that you display metric information in a coherent and effective way.

Automation

Azure Automation delivers a cloud-based automation, operating system updates, and configuration service that supports consistent management across your Azure and non-Azure environments.

Tasks

Select Tasks to help you manage Azure Cache for Redis resources more easily. These tasks vary in number and availability, based on the resource type. Presently, you can only use the Send monthly cost for resource template to create a task while in preview.

Export template

Select Export template to build and export a template of your deployed resources for future deployments. For more information about working with templates, see Deploy resources with Azure Resource Manager templates.

Support & troubleshooting settings

The settings in the Support + troubleshooting section provide you with options for resolving issues with your cache.

• Resource health
• New support request

Resource health

Resource health watches your resource and tells you if it's running as expected. For more information about the Azure Resource health service, see Azure Resource health overview.

New support request

Select New support request to open a support request for your cache.

Default Redis server configuration

New Azure Cache for Redis instances are configured with the following default Redis configuration values:

Setting	Default value	Description
databases	16	The default number of databases is 16 but you can configure a different number based on the pricing tier.1 The default database is DB 0, you can select a different one on a per-connection basis using connection.GetDatabase(dbid) where dbid is a number between 0 and databases - 1.
maxclients	Depends on the pricing tier2	This value is the maximum number of connected clients allowed at the same time. Once the limit is reached Redis closes all the new connections, returning a 'max number of clients reached' error.
maxmemory-reserved	10% of maxmemory	The allowed range for maxmemory-reserved is 10% - 60% of maxmemory. If you try to set these values lower than 10% or higher than 60%, they're reevaluated and set to the 10% minimum and 60% maximum. The values are rendered in megabytes.
maxfragmentationmemory-reserved	10% of maxmemory	The allowed range for maxfragmentationmemory-reserved is 10% - 60% of maxmemory. If you try to set these values lower than 10% or higher than 60%, they're reevaluated and set to the 10% minimum and 60% maximum. The values are rendered in megabytes.
maxmemory-policy	volatile-lru	Maxmemory policy is the setting used by the Redis server to select what to remove when maxmemory (the size of the cache that you selected when you created the cache) is reached. With Azure Cache for Redis, the default setting is volatile-lru. This setting removes the keys with an expiration set using an LRU algorithm. This setting can be configured in the Azure portal. For more information, see Memory policies.
maxmemory-samples	3	To save memory, LRU and minimal TTL algorithms are approximated algorithms instead of precise algorithms. By default Redis checks three keys and picks the one that was used less recently.
lua-time-limit	5,000	Max execution time of a Lua script in milliseconds. If the maximum execution time is reached, Redis logs that a script is still in execution after the maximum allowed time, and starts to reply to queries with an error.
lua-event-limit	500	Max size of script event queue.
client-output-buffer-limit normal / client-output-buffer-limit pubsub	0 0 0 / 32mb 8mb 60	The client output buffer limits can be used to force disconnection of clients that aren't reading data from the server fast enough for some reason. A common reason is that a Pub/Sub client can't consume messages as fast as the publisher can produce them. For more information, see https://redis.io/topics/clients.

Databases

¹The limit for databases is different for each Azure Cache for Redis pricing tier and can be set at cache creation. If no databases setting is specified during cache creation, the default is 16.

• Basic and Standard caches
  • C0 (250 MB) cache - up to 16 databases
  • C1 (1 GB) cache - up to 16 databases
  • C2 (2.5 GB) cache - up to 16 databases
  • C3 (6 GB) cache - up to 16 databases
  • C4 (13 GB) cache - up to 32 databases
  • C5 (26 GB) cache - up to 48 databases
  • C6 (53 GB) cache - up to 64 databases
• Premium caches
  • P1 (6 GB - 60 GB) - up to 16 databases
  • P2 (13 GB - 130 GB) - up to 32 databases
  • P3 (26 GB - 260 GB) - up to 48 databases
  • P4 (53 GB - 530 GB) - up to 64 databases
  • P5 (120 GB - 1200 GB) - up to 64 databases
  • All premium caches with Redis cluster enabled - Redis cluster only supports use of database 0 so the databases limit for any premium cache with Redis cluster enabled is effectively 1 and the Select command isn't allowed.

For more information about databases, see What are Redis databases?

Maxclients

²The maxclients property is different for each Azure Cache for Redis pricing tier.

• Basic and Standard caches
  • C0 (250 MB) cache - up to 256 connections
  • C1 (1 GB) cache - up to 1,000 connections
  • C2 (2.5 GB) cache - up to 2,000 connections
  • C3 (6 GB) cache - up to 5,000 connections
  • C4 (13 GB) cache - up to 10,000 connections
  • C5 (26 GB) cache - up to 15,000 connections
  • C6 (53 GB) cache - up to 20,000 connections
• Premium caches
  • P1 (6 GB - 60 GB) - up to 7,500 connections
  • P2 (13 GB - 130 GB) - up to 15,000 connections
  • P3 (26 GB - 260 GB) - up to 30,000 connections
  • P4 (53 GB - 530 GB) - up to 40,000 connections
  • P5: (120 GB - 1200 GB) - up to 40,000 connections

Redis commands not supported in Azure Cache for Redis

Configuration and management of Azure Cache for Redis instances is managed by Microsoft, which disables the following commands. If you try to invoke them, you receive an error message similar to "(error) ERR unknown command".

• ACL
• BGREWRITEAOF
• BGSAVE
• CLUSTER - Cluster write commands are disabled, but read-only cluster commands are permitted.
• CONFIG
• DEBUG
• MIGRATE
• PSYNC
• REPLICAOF
• REPLCONF - Azure cache for Redis instances don't allow customers to add external replicas. This command is normally only sent by servers.
• SAVE
• SHUTDOWN
• SLAVEOF
• SYNC

For cache instances using active geo-replication, the following commands are also blocked to prevent accidental data loss:

• FLUSHALL
• FLUSHDB

For more information about Redis commands, see https://redis.io/commands.

Related content

• How can I run Redis commands?
• Monitor Azure Cache for Redis