Ceph offers a highly scalable and fault-tolerant storage system. Samba is already capable of sharing data located on the Ceph Filesystem, however scale-out sharing (the same data exposed by multiple Samba nodes) currently requires the use of CTDB for consistent and coherent state across Samba cluster nodes. In such a setup CTDB provides a clustered database with persistent key-value data storage and locking. Database usage is abstracted out via a generic dbwrap interface.

Ceph's librados library provides an API for the storage and retrieval of arbitrary key-value data via the omap functions. A watch/notify protocol is also provided as a mechanism for synchronising client state (locking). Key-value data stored in the RADOS back-end inherits the same redundancy features as regular objects, making it a potentially good candidate as a replacement for CTDB in scale-out Samba clusters.

This task involves the implementation and testing of a new dbwrap back-end that uses librados for the storage, retrieval and locking of Samba key-value state.

upstream idea

previous prototype from hackweek 17