When running ceph-authtool I get the message "error while loading shared libraries: libboost_thread.so.1.64.0: cannot open shared object file: No such file or directory". It appears libboost has been updated recently, however, the Ceph version in the repos (10.2.5) is behind the version in upstream Arch (10.2.9). It seems an updated PKGBUILD has been commited but has not yet been built
https://archlinuxarm.org/packages/aarch64/ceph.