老师 ，你好！

背景：1master 1slave 
我的从节点哨兵启动之后日志打印如下：

31552:X 31 Jul 2020 08:14:22.763 # Redis version=6.0.5, bits=64, commit=00000000, modified=0, pid=31552, just started

31552:X 31 Jul 2020 08:14:22.763 # Configuration loaded

31553:X 31 Jul 2020 08:14:22.764 # Could not create server TCP listening socket 0.0.0.0:26379: bind: Address already in use

31752:X 31 Jul 2020 08:15:43.075 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo

31752:X 31 Jul 2020 08:15:43.075 # Redis version=6.0.5, bits=64, commit=00000000, modified=0, pid=31752, just started

31752:X 31 Jul 2020 08:15:43.075 # Configuration loaded

31753:X 31 Jul 2020 08:15:43.076 * Running mode=sentinel, port=26379.

31753:X 31 Jul 2020 08:15:43.076 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.

31753:X 31 Jul 2020 08:15:43.077 # Sentinel ID is 21d0784bcde019bc2cc4b1edea939997047e68c5

31753:X 31 Jul 2020 08:15:43.077 # +monitor master imooc-master 172.17.16.2 6379 quorum 2

31753:X 31 Jul 2020 08:16:13.140 # +sdown slave 172.16.0.10:6379 172.16.0.10 6379 @ imooc-master 172.17.16.2 6379

为什么是sdown呢？我的配置文件是从主节点复制过来的。