复制缓冲区大小，这是一个环形复制缓冲区，用来保存最新复制的命令。这样在slave离线的时候，不需要完全复制master的数据，如果可以执行部分同步，只需要把缓冲区的部分数据复制给slave，就能恢复正常复制状态。缓冲区的大小越大，slave离线的时间可以更长，复制缓冲区只有在有slave连接的时候才分配内存。没有slave的一段时间，内存会被释放出来，默认1m。
# Set the replication backlog size. The backlog is a buffer that accumulates
# slave data when slaves are disconnected for some time, so that when a slave
# wants to reconnect again, often a full resync is not needed, but a partial
# resync is enough, just passing the portion of data the slave missed while
# disconnected.
#设置复制backlog大小。backlog是一个缓冲器(buffer)，当slave断开一段时间时积累slave数据，以便当slave想要再次重新连接时，通常不需要再“完全同步（full resync）”，而是“部分再同步（partial resync）”就足够了，仅仅传输slave在断开连接时错失的那部分数据（余下的）即可。
#
# The bigger the replication backlog, the longer the time the slave can be
# disconnected and later be able to perform a partial resynchronization.
#复制backlog越大，slave可以断开连接的时间就越长，之后就可以执行”部分重新同步（partial resynchronization）“。
# The backlog is only allocated once there is at least a slave connected. 只有在至少有一个slave连接时才分配backlog。
#
# repl-backlog-size 1mb
# After a master has no longer connected slaves for some time, the backlog
# will be freed. The following option configures the amount of seconds that
# need to elapse, starting from the time the last slave disconnected, for
# the backlog buffer to be freed.
# master没有slave一段时间会释放复制缓冲区的内存，repl-backlog-ttl用来设置该时间长度。单位为秒。
#在master已经不再连接slave一段时间后，backlog将被释放。 以下选项配置需要经过的秒数，从最后一个slave服务器断开的时间开始，backlog缓冲区被释放。
# A value of 0 means to never release the backlog. 值为0表示永不释放backlog
#
# repl-backlog-ttl 3600
---------------------------------
# 当master不可用，Sentinel会根据slave的优先级选举一个master。最低的优先级的slave，当选master。而配置成0，永远不会被选举。
# The slave priority is an integer number published by Redis in the INFO output.
# It is used by Redis Sentinel in order to select a slave to promote into a
# master if the master is no longer working correctly.
#slave优先级是由Redis在INFO输出中发布的整数。 它由Redis Sentinel使用，以便选择slave，如果master不再正常工作，则升级为主设备。
# A slave with a low priority number is considered better for promotion, so
# for instance if there are three slaves with priority 10, 100, 25 Sentinel will
# pick the one with priority 10, that is the lowest.
#具有低优先级编号的slave被认为更好地用于提升，因此例如如果存在具有优先级10,100,25的三个从设备，则哨兵将选择具有优先级10，即最低的那个。
# However a special priority of 0 marks the slave as not able to perform the
# role of master, so a slave with priority of 0 will never be selected by
# Redis Sentinel for promotion.
#然而，0的特殊优先级标志着slave不能执行主设备的角色，因此优先级为0的从设备将不会被Redis Sentinel选择用于升级。
# By default the priority is 100.
slave-priority 100
-----------------------------------------
#
# It is possible for a master to stop accepting writes if there are less than
# N slaves connected, having a lag less or equal than M seconds.
#如果连接少于N个slave，具有小于或等于M秒的滞后，则master可以停止接受写入。
# The N slaves need to be in "online" state.
#
# The lag in seconds, that must be <= the specified value, is calculated from
# the last ping received from the slave, that is usually sent every second.
#以秒为单位的滞后，必须小于指定值，根据从slave接收的最后一次ping计算，通常每秒发送一次。
# This option does not GUARANTEE that N replicas will accept the write, but
# will limit the window of exposure for lost writes in case not enough slaves
# are available, to the specified number of seconds.
#此选项不保证N个副本将接受写入，但会在没有足够的slave可用的情况下,将丢失写入的曝光窗口限制为指定的秒数。
# For example to require at least 3 slaves with a lag <= 10 seconds use: 例如，至少需要3个slave，lag小于10s
#