When a in-memory database is used primarily as a cache, eventually that database will become full. In order to continue operating, objects must be evicted from memory (essentially, deleted) to free up space. Some common strategies for determining what to evict include: LRU (Least Recently Used), where the least recently accessed keys are evicted first when an eviction is reguired LFU (Least Frequently Used), where the least frequently accessed keys are evicted first when an eviction is required Random, where a random key is evicted when an eviction is required No Eviction, where an error is raised rather than ever evicting a key Which statement about eviction policies is most TRUE? O Memcached supports the Random or LRU eviction strategles, whereas Redis never evicts keys and instead always raises an error when RAM is exhausted. Redis supports all of the above strategies, and Memcached supports only LRU and LFU. Typically an application will configure all available data stores with a similar eviction policy. Both Memcached and Redis support all of the above strategies, and you should configure Memcached or Redis appropriately as required by the application. Both Redis and Memcached support all of the above strategies except for Random. FU is always inferior to LRU and should never be used. While Redis supports all of the above strategies, Memcached only supports an RU eviction policy. It is conceivable that certain applications would benefit from multiple Redis servers with different eviction policies for different storage needs.
