If by "strong consistency" you mean "linearizability" then no, you can build a distributed atomic register without locking (ABD algorithm[0][1]). The trick is t

If by "strong consistency" you mean "linearizability" then no, you can build a distributed atomic register without locking (ABD algorithm[0][1]). The trick is to force readers to complete a possibly-incomplete write returned from a read quorum by writing it to a write quorum before they can return their result (in practice you can elide the write-on-read in the common case where the result from the read quorum already is written to a write quorum). Similarly, writers must find the latest possibly-written version from a read quorum to obtain the version number for their write. If you need stronger primitives than atomic read/write (e.g. CAS), then ABD is insufficient and you need consensus in the asynchronous model (although synchronized clocks can allow even CAS to be implemented with ABD + leader election with leases[2]). [0] https://dl.acm.org/doi/pdf/10.1145/200836.200869 https://dl.acm.org/doi/pdf/10.1145/200836.200869 [1] https://www.cl.cam.ac.uk/teaching/2223/ConcDisSys/dist-sys-notes.pdf https://www.cl.cam.ac.uk/teaching/2223/ConcDisSys/dist-sys-n... [2] https://arxiv.org/pdf/1702.04242.pdf https://arxiv.org/pdf/1702.04242.pdf