ubuntu18安装redis后未开机启动Could not connect to Redis at 127.0.0.1:6379: Connection refused解决办法

阿里云ubuntu18安装redis后,

apt install redis-server

redis-cli提示Could not connect to Redis at 127.0.0.1:6379: Connection refused

最终发现是两方面导致:

1. ubuntu18未将redis加入到systemctl中

sudo systemctl enable redis-server.service

 

2.redis默认监听了ipv6导致启动失败

sudo  vim /etc/redis/redis.conf 

将bind 127.0.0.1 ::1

修改为bind 127.0.0.1

 

reboot

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另新安装的redis会有三个报错信息

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

意思是：TCP  backlog设置值，511没有成功，因为 /proc/sys/net/core/somaxconn这个设置的是更小的128.

临时解决方法：（即下次启动还需要修改此值）

echo 511 > /proc/sys/net/core/somaxconn

永久解决方法：（即以后启动还需要修改此值）

将其写入/etc/rc.local文件中。
 

2.overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to/etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.

意思是：overcommit_memory参数设置为0！在内存不足的情况下，后台程序save可能失败。建议在文件 /etc/sysctl.conf 中将overcommit_memory修改为1。

临时解决方法：echo "vm.overcommit_memory=1" >> /etc/sysctl.conf

永久解决方法：将其写入/etc/sysctl.conf文件中。
 

3.you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix thisissue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain thesetting after a reboot. Redis must be restarted after THP is disabled.

意思是：你使用的是透明大页，可能导致redis延迟和内存使用问题。执行 echo never > /sys/kernel/mm/transparent_hugepage/enabled 修复该问题。

临时解决方法：

echo never > /sys/kernel/mm/transparent_hugepage/enabled。

永久解决方法：

将其写入/etc/rc.local文件中。
 

另附rc.local写法

写法1

sudo vim /etc/rc.local

#!/bin/sh -e
echo never > /sys/kernel/mm/transparent_hugepage/enabled
echo 511 > /proc/sys/net/core/somaxconn

:x保存

写法2

echo '#!/bin/sh -e' >>/etc/rc.local

echo 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' >>/etc/rc.local

echo 'echo 511 > /proc/sys/net/core/somaxconn' >>/etc/rc.local

 

最后

sudo chmod 777 /etc/rc.local

reboot

即可