> For e-commerce workloads, the performance benefit of write-back mode isn’t worth the data integrity risk. Our customers depend on transactional consistency, and write-through mode ensures every write operation is safely committed to our replicated Ceph storage before the application considers it complete.

Unless the writer is always overwriting entire files at once blindly (doesn't read-then-write), consistency requires consistency reads AND writes. Even then, potential ordering issues creep in. It would be really interesting to hear how they deal with it.