Redis必要的一些配置

[root@localhost202 redis-2.8.19]# /usr/local/redis/bin/redis-server >> /data/redis-start.txt   #从定向到文件，方便我们查看，内容如下：

[root@localhost202 redis-2.8.19]# cat /data/redis-start.txt

[]  Jan ::42.506 # Warning: no config file specified, using the default config. In order to specify a config file use /usr/local/redis/bin/redis-server /path/to/redis.conf
[]  Jan ::42.508 * Increased maximum number of open files to  (it was originally set to ).
[]  Jan ::42.509 # Warning:  bit instance detected but no memory limit set. Setting  GB maxmemory limit with 'noeviction' policy now.
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 |`-._`-...-` __...-.``-._|'` _.-'|     Port:
 |    `-._   `._    /     _.-'    |     PID: 6033
  `-._    `-._  `-./  _.-'    _.-'
 |`-._`-._    `-.__.-'    _.-'_.-'|
 |    `-._`-._        _.-'_.-'    |           http://redis.io
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 |`-._`-._    `-.__.-'    _.-'_.-'|
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[]  Jan ::42.511 # Server started, Redis version 2.8.
[]  Jan ::42.511 # WARNING overcommit_memory is set to ! 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.
[]  Jan ::42.511 # WARNING: The TCP backlog setting of  cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of .
[]  Jan ::42.511 * DB loaded from disk: 0.000 seconds
[]  Jan ::42.511 * The server is now ready to accept connections on port
[ | signal handler] () Received SIGINT scheduling shutdown...
[]  Jan ::46.643 # User requested shutdown...
[]  Jan ::46.643 * Saving the final RDB snapshot before exiting.
[]  Jan ::46.663 * DB saved on disk
[]  Jan ::46.663 # Redis is now ready to exit, bye bye...

1、增加配置文件

2、配置maxmemory

3、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.

配置：

1. 为了防止内存爆满导致系统崩溃，需要设置/etc/redis/*.cnf中的maxmemory
2. 防止报错，可以调整内存分配策略

   /etc/sysctl.conf 这个是Redis日志中可以看到的建议：
      添加vm.overcommit_memory=1保存，并执行：sysctl vm.overcommit_memory=1使之生效
   
   /proc/sys/vm/overcommit_memory,这个里面就是overcommit_memory值，这个可以被上面的设置更新.
     0， 表示内核将检查是否有足够的可用内存供应用进程使用；如果有足够的可用内存，内存申请允许；否则，内存申请失败，并把错误返回给应用进程。
     1， 表示内核允许分配所有的物理内存，而不管当前的内存状态如何。
     2， 表示内核允许分配超过所有物理内存和交换空间总和的内存