打开redis.conf配置文件看到如下：

# -----------------------------------------------------------------------------
#
# 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
# received 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
# Copy on Write memory and replica 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:
#
# "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 current db contents in RAM while parsing the data directly
#                 from the socket. Replicas in this mode can keep serving current
#                 data set while replication is in progress, except for cases where
#                 they can't recognize master as having a data set from same
#                 replication history.
#                 Note that this requires sufficient memory, if you don't have it,
#                 you risk an OOM kill.
repl-diskless-load disabled

修改repl-diskless-load

# 将disabled更改为on-empty-db否则可能同步失败
repl-diskless-load on-empty-db