Cephalocon 2024

Deutsche Telekom operates a growing email system with several million accounts and billions of emails stored on traditional NFS. Six years ago we introduced librmb (librados mailbox) to the community, a universal open source library to store emails in a Ceph cluster. Librmb uses RADOS to store email directly in Ceph to achieve maximum performance through parallel access from many email gateways simultaneously, for millions of active customers. Email systems are much too complex to be simulated in a way which would allow to verify if the switch to librmb will work for a large number of users. Therefore a field test with active customers was necessary to provide an educated guess on the behavior of the final setup. This presentation will cover the results from artificial and real field tests with more than 1 million accounts/users. The results include the experience and learnings of migrating from the existing email system into Ceph, an extended time of running the system and from migrating the accounts out of the test system. We will provide an insight into our learnings, found issues, potential solutions and an outlook into our next steps towards a Ceph based email system.