Apart from the NTP tangent, this sounds like a Linux XFS / ServeRAID M5210 firmware issue. Your XFS filesystems created using the incorrect block/io sizes reported by the RAID controller would have been unmountable on the newer Linux kernel regardless of Ceph.
Lesson learned: your configuration management also needs to control for firmware versions such that the same issue would have shown up in a dev/test environment before turning into a prod nightmare :/
Lesson learned: your configuration management also needs to control for firmware versions such that the same issue would have shown up in a dev/test environment before turning into a prod nightmare :/