"Most enterprise email solutions make use of traditional local file systems or shared file systems like NFS to store data, indexes and caches. Software-defined storage solutions such as Ceph have disrupted the storage market in the last few years because they offer more options, like object store.
For emails, object store is a logical choice as a storage backend. Ceph offers two object store backends: Rados Gateway (RGW) via S3/Swift and librados itself to store objects directly in a Ceph cluster. For an email system with millions of active customers, the Rados Gateway would very likely become a bottleneck. To achieve maximum performance using parallel I/O from all clients, librados is the best option because it uses the native RADOS protocol and involves fewer software layers.
This talk will provide insight in what Deutsche Telekom, together with partners and SUSE products, is doing to move from NFS to Ceph-based storage for email. To make use of Ceph, we developed an open source library called librmb (librados mailbox) to unify email storage via librados."