The eviction policy designates a data eviction method for Redis Enterprise Software (RS) to use when the database size reaches its limit. You can select any of the following:

Policy Description
 noeviction Returns an error if the memory limit has been reached when trying to insert more data
 allkeys-lru Evicts the least recently used keys out of all keys
 allkeys-lfu Evicts the least frequently used keys out of all keys
 allkeys-random Randomly evicts keys out of all keys
 volatile-lru Evicts the least recently used keys out of all keys with an "expire" field set
 volatile-lfu Evicts the least frequently used keys out of all keys with an "expire" field set
 volatile-random Randomly evicts keys with an "expire" field set
 volatile-ttl Evicts the shortest time-to-live and least recently used keys out of all keys with an "expire" field set.

One mechanism to avoid this, but still keep performance is to use Redis on Flash. It can span your database across RAM + Flash Memory and intelligently manage what data is hot and should be in RAM and what data is not and can be on Flash memory (SSD).

Note: Geo-Distributed CRDBs always operate in noeviction mode.

Warning: Some redis Modules do not fully support eviction or all eviction types. Please see each module's documentation for more information on this topic.