--- a/configs/client/burp.conf.in
+++ b/configs/client/burp.conf.in
@@ -10,7 +10,8 @@
 # 0 to decide automatically, 1 to force protocol1 mode (file level granularity
 # with a pseudo mirrored storage on the server and optional rsync). 2 forces
 # protocol2 mode (inline deduplication with variable length blocks).
-# protocol = 0
+# WARNING: as of September 2017 protocol2 is still considered experimental.
+protocol = 1
 pidfile = @runstatedir@/@name@.client.pid
 syslog = 0
 stdout = 1
--- a/configs/server/burp.conf.in
+++ b/configs/server/burp.conf.in
@@ -21,7 +21,8 @@
 # protocol2 mode (inline deduplication with variable length blocks).
 # Like many other settings, this can be set per client in the clientconfdir
 # files.
-# protocol = 0
+# WARNING: as of September 2017 protocol2 is still considered experimental.
+protocol = 1
 pidfile = @runstatedir@/@name@.server.pid
 hardlinked_archive = 0
 working_dir_recovery_method = delete