Memory and performance on Docs

Eviction policy

Mon, 01 Jan 0001 00:00:00 +0000

The eviction policy determines what happens when a database reaches its memory limit.

To make room for new data, older data is evicted (removed) according to the selected policy.

To prevent this from happening, make sure your database is large enough to hold all desired keys.

Eviction Policy	Description
noeviction	New values aren't saved when memory limit is reached When a database uses replication, this applies to the primary database
allkeys-lru	Keeps most recently used keys; removes least recently used (LRU) keys
allkeys-lfu	Keeps frequently used keys; removes least frequently used (LFU) keys
allkeys-random	Randomly removes keys
volatile-lru	Removes least recently used keys with `expire` field set to true
volatile-lfu	Removes least frequently used keys with `expire` field set to true
volatile-random	Randomly removes keys with `expire` field set to true
volatile-ttl	Removes least frequently used keys with `expire` field set to true and the shortest remaining time-to-live (TTL) value

Eviction policy defaults

volatile-lru is the default eviction policy for most databases.

Database memory limits

Mon, 01 Jan 0001 00:00:00 +0000

When you set a database's memory limit, you define the maximum size the database can reach in the cluster, across all database replicas and shards, including both primary and replica shards.

If the total size of the database in the cluster reaches the memory limit, the data eviction policy is applied.

Factors for sizing

Factors to consider when sizing your database:

Shard placement policy

Mon, 01 Jan 0001 00:00:00 +0000

In Redis Enterprise Software, the location of master and replica shards on the cluster nodes can impact the database and node performance. Master shards and their corresponding replica shards are always placed on separate nodes for data resiliency. The shard placement policy helps to maintain optimal performance and resiliency.

In addition to the shard placement policy, considerations that determine shard placement are:

Separation of master and replica shards
Available persistence and Auto Tiering storage
Rack-zone awareness
Memory available to host the database when fully populated

The shard placement policies are: