BlueStore was designed to address these limitations. From the development of NewStore, it was obvious that trying to use a POSIX filesystem as the underlying storage layer in any approach would introduce a number of issues that were also present in filestore. In order for Ceph to be able to get the guarantees, it not only needed from the storage but also without the overheads of a filesystem, Ceph needed to have direct block level access to the storage devices. By storing metadata in RocksDB and the actual object data directly on block devices, Ceph can leverage much better control over the underlying storage and at the same time, also provide better performance.