Mark diskless loads as experimental in redis.conf.

Author: antirez

redis.conf

@@ -375,15 +375,25 @@ repl-diskless-sync no
 # it entirely just set it to 0 seconds and the transfer will start ASAP.
 repl-diskless-sync-delay 5
 
-# Replica can load the rdb it reads from the replication link directly from the
-# socket, or store the rdb to a file and read that file after it was completely
+# -----------------------------------------------------------------------------
+# WARNING: RDB diskless load is experimental. Since in this setup the replica
+# does not immediately store an RDB on disk, it may cause data loss during
+# failovers. RDB diskless load + Redis modules not handling I/O reads may also
+# cause Redis to abort in case of I/O errors during the initial synchronization
+# stage with the master. Use only if your do what you are doing.
+# -----------------------------------------------------------------------------
+#
+# Replica can load the RDB it reads from the replication link directly from the
+# socket, or store the RDB to a file and read that file after it was completely
 # recived from the master.
+#
 # In many cases the disk is slower than the network, and storing and loading
-# the rdb file may increase replication time (and even increase the master's
+# the RDB file may increase replication time (and even increase the master's
 # Copy on Write memory and salve buffers).
-# However, parsing the rdb file directly from the socket may mean that we have
-# to flush the contents of the current database before the full rdb was received.
-# for this reason we have the following options:
+# However, parsing the RDB file directly from the socket may mean that we have
+# to flush the contents of the current database before the full rdb was
+# received. For this reason we have the following options:
+#
 # "disabled"    - Don't use diskless load (store the rdb file to the disk first)
 # "on-empty-db" - Use diskless load only when it is completely safe.
 # "swapdb"      - Keep a copy of the current db contents in RAM while parsing