--- /dev/null
+# This file is part of systemd.
+#
+# systemd is free software; you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation; either version 2.1 of the License, or
+# (at your option) any later version.
+
+# See tmpfiles.d(5) for details
+
+# Set the NOCOW attribute for directories of journal files. This flag
+# is inheredited by their new files and sub-directories. Matters only
+# for btrfs filesystems.
+#
+# WARNING: Enabling the NOCOW attribute improves journal performance
+# substantially, but also disables the btrfs checksum logic. In
+# btrfs RAID filesystems the checksums are needed for rebuilding
+# corrupted files. Without checksums such rebuilds are not
+# possible.
+#
+# In a single-disk filesystem (or a filesystem without redundancy)
+# enabling the NOCOW attribute for journal files is safe, because
+# they have their own checksums and a rebuilding wouldn't be possible
+# in any case.
+
+#h /var/log/journal - - - - +C
+#h /var/log/journal/%m - - - - +C
+#h /var/log/journal/remote - - - - +C