Ceph » CephFS

I want to mirror a snapshot in Ceph v16.2.6 deployed with cephadm using the stock quay.io images. My source file system has a folder "/src/folder/x" where "/src/folder" has mode "ug=r,o=", in other words no write permissions for the owner (root).

The sync of a snapshot "initial" now fails with the following log excerpt.

remote_mkdir: remote epath=./src/folder/x
remote_mkdir: failed to create remote directory=./src/folder/x: (13) Permission denied
do_synchronize: closing local directory=./src/folder
do_synchronize: closing local directory=./src/
do_synchronize: closing local directory=.
post_sync_close_handles
do_sync_snaps: failed to synchronize dir_root=/src/folder, snapshot=initial
sync_snaps: failed to sync snapshots for dir_root=/src/folder

The capabilites on the remote are

client.mirror-tier-2-remote
       key: REDACTED
       caps: [mds] allow * fsname=cephfs
       caps: [mon] allow r fsname=cephfs
       caps: [osd] allow * tag cephfs data=cephfs