This section of pages contains content that describes the main concepts that Redis Cloud is built around.
Redis is mostly a single-threaded process. This enables Redis to be high performance and simple (no need for threads synchronization). To let you take advantage of Redis clustering, Redis Cloud uses our Redis Enterprise technology to scale Redis databases for you. For example: The dataset is big enough that it would benefit from using the RAM resources of more than one server. We recommend enabling clustering for the database when the data reaches the size of 25 GB (50 GB for RoF) to create multiple shards.
For each database, you can choose from these data eviction policies: Options Description allkeys-lru Evicts the least recently used (LRU) keys out of all keys in the database allkeys-lfu Evicts the least frequently used keys out of all keys allkeys-random Randomly evicts keys out of all keys in the database volatile-lru (default) Evicts the least recently used (LRU) keys out of 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 keys with an “expire” field set no eviction Returns error if memory limit has been reached when trying to insert more data Redis Cloud supports Redis on Flash (RoF) to prevent data eviction but maintain high performance.
Redis Cloud supports persisting your data to disk on a per-database basis and in multiple ways. Unlike a few cloud provider’s Redis offerings, Redis Cloud has two options for persistence, Append Only File (AOF) and Snapshot (RDB). Data-persistence is always performed over a persistent storage that is attached to the cloud instance (e.g. AWS EBS). This makes sure that there is no data lost in case of a node failure event because the new cloud instance will be attached to the existing persistent storage volume.