BlueStore is a new backend for the Ceph OSD daemons. Its highlights are better performance (roughly 2x for writes), full data checksumming, and built-in compression. Compared to the currently used FileStore backend, BlueStore allows for storing objects directly on the Ceph Block Device without requiring any filesystem interface. BlueStore is the new default storage backend for the Luminous (12.2.z) release and will be used by default when provisioning new OSDs. BlueStore is not considered production ready in Jewel and it is not recommended to run any production Jewel clusters with BlueStore as a backend.

Some of BlueStore's features and enhancements are:

• RocksDB backend: Metadata is stored in a RocksDB backend as opposed to FileStore's current LevelDB. RocksDB is a multithreaded backend and is much more performant than the current LevelDB backend.
• Multi-device support: BlueStore can use multiple block devices for storing different data.
• No large double-writes: BlueStore will only fall back to typical write-ahead journaling scheme if write size is below a certain configurable threshold.
• Efficient block device usage: BlueStore doesn't use a filesystem so it minimizes the need to clear the storage device cache.
• Flexible allocator: BlueStore can implement different policies for different types of storage devices. Basically setting different behaviors between SSDs and HDDs.