告警信息

WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.

翻译为：【警告：无法强制执行TCP backlog设置511，因为/proc/sys/net/core/somaxconn设置为较低的值128。】

解决方法

方式一：设置的值128较低，需要“echo 511 > /proc/sys/net/core/somaxconn”命令，注意此命令只是暂时生效，如果重启后就会失效。

方式二：永久解决Redis中The TCP backlog setting of 511 cannot be enforced告警问题，编辑/etc/sysctl.conf文件，添加net.core.somaxconn = 1024然后执行sysctl -p命令查看是否添加成功，之后重启Redis服务即可。

[root@mrwang redis-4.0.9]# vim /etc/sysctl.conf 
[root@mrwang redis-4.0.9]# sysctl -p            
vm.swappiness = 0
kernel.sysrq = 1
net.ipv4.neigh.default.gc_stale_time = 120
net.ipv4.conf.all.rp_filter = 0
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.lo.arp_announce = 2
net.ipv4.conf.all.arp_announce = 2
net.ipv4.tcp_max_tw_buckets = 5000
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 1024
net.ipv4.tcp_synack_retries = 2
net.core.somaxconn = 1024

来源：https://blog.yoodb.com/yoodb/article/detail/1721