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title description author ms.service ms.topic ms.date ms.author
How to configure Azure Cache for Redis
Understand the default Redis configuration for Azure Cache for Redis and learn how to configure your Azure Cache for Redis instances
flang-msft
cache
conceptual
06/07/2022
franlanglois

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.

Note

For more information on configuring and using premium cache features, see How to configure persistence, How to configure clustering, and How to configure Virtual Network support.

Configure Azure Cache for Redis settings

[!INCLUDE redis-cache-create]

Azure Cache for Redis settings are viewed and configured on the Azure Cache for Redis on the left using the Resource Menu.

:::image type="content" source="media/cache-configure/redis-cache-settings.png" alt-text="Azure Cache for Redis Settings":::

You can view and configure the following settings using the Resource Menu. The settings that you see depend on the tier of your cache. For example, you don't see Reboot when using the Enterprise tier.

Overview

Overview 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 Azure Cache for Redis events, see alerts.

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.

Settings

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

Access keys

Select Access keys to view or regenerate the access keys for your cache. These keys are used by the clients connecting to your cache.

:::image type="content" source="media/cache-configure/redis-cache-manage-keys.png" alt-text="Azure Cache for Redis Access Keys":::

Advanced settings

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

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.

Note

TLS access to Azure Cache for Redis supports TLS 1.0, 1.1 and 1.2 currently, but versions 1.0 and 1.1 are being retired soon. Please read our Remove TLS 1.0 and 1.1 page for more details.

:::image type="content" source="media/cache-configure/redis-cache-access-ports.png" alt-text="Azure Cache for Redis Access Ports":::

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.

:::image type="content" source="media/cache-configure/redis-cache-maxmemory-policy.png" alt-text="Azure Cache for Redis Maxmemory Policy":::

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.
  • allkeys-lru
  • volatile-random
  • allkeys-random
  • volatile-ttl
  • noeviction

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 non-cache 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 will have 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 Available metrics and reporting intervals.

Important

The maxmemory-reserved and maxfragmentationmemory-reserved settings are available only for Standard and Premium caches.

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.

:::image type="content" source="media/cache-configure/redis-cache-advanced-settings.png" alt-text="Azure Cache for Redis Advanced Settings":::)

Important

Keyspace notifications and the notify-keyspace-events setting are only available for Standard and Premium caches.

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

Azure Cache for Redis Advisor

The Azure Cache for Redis Advisor on the left displays recommendations for your cache. During normal operations, no recommendations are displayed.

:::image type="content" source="media/cache-configure/redis-cache-no-recommendations.png" alt-text="Screenshot that shows where the recommendations are displayed.":::

If any conditions occur during the operations of your cache such as high memory usage, network bandwidth, or server load, an alert is displayed on the Azure Cache for Redis on the left.

:::image type="content" source="media/cache-configure/redis-cache-recommendations-alert.png" alt-text="Screenshot that shows where alerts are displayed in the Azure Cache for Redis section.":::

Further information can be found on the Recommendations on the left.

:::image type="content" source="media/cache-configure/redis-cache-recommendations.png" alt-text="Recommendations":::)

You can monitor these metrics on the Monitoring charts and Usage charts sections of the Azure Cache for Redis on the left.

Each pricing tier has different limits for client connections, memory, and bandwidth. If your cache approaches maximum capacity for these metrics over a sustained period of time, a recommendation is created. For more information about the metrics and limits reviewed by the Recommendations tool, see the following table:

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

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.

:::image type="content" source="media/cache-configure/pricing-tier.png" alt-text="Azure Cache for Redis pricing tier":::

Cluster Size

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

:::image type="content" source="media/cache-configure/redis-cache-redis-cluster-size.png" alt-text="Cluster size":::

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.

Important

Redis clustering is only available for Premium caches. For more information, see How to configure clustering for a Premium Azure Cache for Redis.

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.

Important

Redis data persistence is only available for Premium caches.

Schedule updates

The Schedule updates on the left allow you to choose a maintenance window for Redis server updates for your cache.

Important

The maintenance window applies only to Redis server updates, and not to any Azure updates or updates to the operating system of the VMs that host the cache.

:::image type="content" source="media/cache-configure/redis-schedule-updates.png" alt-text="Schedule updates":::

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 Azure Cache for Redis administration - Schedule updates

Geo-replication

Geo-replication, on the left, 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.

Important

Geo-replication is only available for Premium tier caches. For more information and instructions, see How to configure Geo-replication for Azure Cache for Redis.

Virtual Network

The Virtual Network section allows you to configure the virtual network settings for your cache. 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.

Important

Virtual network settings are only available for premium caches that were configured with VNET support during cache creation.

Firewall

Firewall rules configuration is available for all Azure Cache for Redis tiers.

Select Firewall to view and configure firewall rules for cache.

:::image type="content" source="media/cache-configure/redis-firewall-rules.png" alt-text="Firewall":::

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.

Important

Connections from Azure Cache for Redis monitoring systems are always permitted, even if firewall rules are configured.

Properties

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

:::image type="content" source="media/cache-configure/redis-cache-properties.png" alt-text="Azure Cache for Redis Properties":::

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.

Automation script

Select Automation script 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.

Administration settings

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

:::image type="content" source="media/cache-configure/redis-cache-administration.png" alt-text="Administration":::

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.

Import can be used to bring Redis compatible RDB files from any Redis server running in any cloud or environment, including Redis running on Linux, Windows, or any cloud provider such as Amazon Web Services and others. Importing data is an easy way to create a cache with pre-populated 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.

Important

Import/Export is only available for Premium tier caches. For more information and instructions, see Import and Export data in Azure Cache for Redis.

Reboot

The Reboot item on the left 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.

:::image type="content" source="media/cache-configure/redis-cache-reboot.png" alt-text="Reboot":::

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

:::image type="content" source="media/cache-configure/redis-cache-reboot-cluster.png" alt-text="Screenshot that shows where to 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 shard(s) to reboot and then select Reboot. After a few minutes, the selected node(s) reboot, and are back online a few minutes later.

Important

Reboot is not yet available for the Enterprise tier. Reboot is available for all other tiers. For more information and instructions, see Azure Cache for Redis administration - Reboot.

Monitoring

The Monitoring section allows you to configure diagnostics and monitoring for your Azure Cache for Redis. For more information on Azure Cache for Redis monitoring and diagnostics, see How to monitor Azure Cache for Redis.

:::image type="content" source="media/cache-configure/redis-cache-diagnostics.png" alt-text="Diagnostics":::

Redis metrics

Select Redis metrics to view metrics for your cache.

Alert rules

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

Diagnostics

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 to configure the storage account used to store cache diagnostics.

Note

In addition to archiving your cache metrics to storage, you can also stream them to an Event hub or send them to Azure Monitor logs.

Support & troubleshooting settings

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

:::image type="content" source="media/cache-configure/redis-cache-support-troubleshooting.png" alt-text="Support and troubleshooting":::

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.

Note

Resource health is currently unable to report on the health of Azure Cache for Redis instances hosted in a virtual network. For more information, see Do all cache features work when hosting a cache in a VNET?

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:

Note

The settings in this section cannot be changed using the StackExchange.Redis.IServer.ConfigSet method. If this method is called with one of the commands in this section, an exception similar to the following example is thrown:

StackExchange.Redis.RedisServerException: ERR unknown command 'CONFIG'

Any values that are configurable, such as max-memory-policy, are configurable through the Azure portal or command-line management tools such as Azure CLI or PowerShell.

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 normalclient-output-buffer-limit pubsub 0 0 032mb 8 mb 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.

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, see Do I need to make any changes to my client application to use clustering?

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

Note

The databases setting can be configured only during cache creation and only using PowerShell, CLI, or other management clients. For an example of configuring databases during cache creation using PowerShell, see New-AzRedisCache.

2maxclients 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

Note

While each size of cache allows up to a certain number of connections, each connection to Redis has overhead associated with it. An example of such overhead would be CPU and memory usage as a result of TLS/SSL encryption. The maximum connection limit for a given cache size assumes a lightly loaded cache. If load from connection overhead plus load from client operations exceeds capacity for the system, the cache can experience capacity issues even if you have not exceeded the connection limit for the current cache size.

Redis commands not supported in Azure Cache for Redis

Important

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

  • BGREWRITEAOF
  • BGSAVE
  • CONFIG
  • DEBUG
  • MIGRATE
  • SAVE
  • SHUTDOWN
  • SLAVEOF
  • REPLICAOF
  • ACL
  • CLUSTER - Cluster write commands are disabled, but read-only Cluster commands are permitted.

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

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 all cache tiers.

Important

  • The Redis Console does not work with VNET. When your cache is part of a VNET, only clients in the VNET can access the cache. Because Redis Console runs in your local browser, which is outside the VNET, it can't connect to your cache.
  • Not all Redis commands are supported in Azure Cache for Redis. For a list of Redis commands that are disabled for Azure Cache for Redis, see the previous Redis commands not supported in Azure Cache for Redis section. For more information about Redis commands, see https://redis.io/commands.

To access the Redis Console, select Console from the Azure Cache for Redis on the left.

:::image type="content" source="media/cache-configure/redis-console-menu.png" alt-text="Screenshot that highlights the Console button.":::

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

:::image type="content" source="media/cache-configure/redis-console.png" alt-text="Screenshot that shows the Redis Console with the input command and results.":::

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.

:::image type="content" source="media/cache-configure/redis-console-premium-cluster.png" alt-text="Redis console":::

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)

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.

:::image type="content" source="media/cache-configure/redis-cache-move.png" alt-text="Move Azure Cache for Redis":::

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.

Next steps