pkg-message-server.in says: 53 NB. If you're not using a checksumming filesystem like ZFS, you might 54 wish to enable data checksumming. It can only be enabled during 55 the initdb phase, by adding the "--data-checksums" flag to 56 the postgres_initdb_flags rcvar. Check the initdb(1) manpage 57 for more info and make sure you understand the performance 58 implications. The actual rcvar is not postgres_initdb_flags, but postgresql_initdb_flags. The same applies to databases/postgresql10-server port (didn't check the earlier). Thank you.