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nosql之redis高可用性集群方案，应急维护技巧
时间：2014-06-12 12:52:30 点击: 来源： 作者：
nosql之redis高可用性集群方案，应急维护技巧前提：现在有主从结构，主库没有配置持久化，从库配置AOF。(主库用来备份和写服务，从库用来提供读服务)场景：哪天主库突然宕了，怎么办？ www.2cto.com 方法：连上从库，做save操作 ...
nosql之redis高可用性集群方案，应急维护技巧前提：现在有主从结构，主库没有配置持久化，从库配置AOF。(主库用来备份和写服务，从库用来提供读服务)场景：哪天主库突然宕了，怎么办？ www.2cto.com 方法：连上从库，做save操作。将会在从库的data目录保存一份从库最新的dump.rdb文件。将这份dump.rdb文件拷贝到主库的data目录下。再重启主库。 就因为这个我想到了用集群的方案，但是redis官方没有mysql那样的master-master的模式~ 这样的情况下，只能咱们自己想办法了~ 
实现的原理~当 Master 与 Slave 均运作正常时, Master负责读，Slave负责同步；当 Master 挂掉，Slave 正常时, Slave接管服务，同时关闭主从复制功能；然后依次循环。这样，两台redis服务器中的任何一台挂掉，都会由另一台继续提供服务，不会对网站形成可察觉的影响，也不会丢失数据。你也可以实现当 Master 恢复正常，则从Slave同步数据，同步数据之后关闭主从复制功能，恢复Master身份，于此同时Slave等待Master同步数据完成之后，恢复Slave身份。高可用方面需要把读写进行分离的，写的话，就指向到一个vip~ 那两个主 用keepalived加脚本进行判断。读的话，尽量用haproxy进行分流，这样的话，哪怕一个从down的话，haproxy会自动剔除的~ redis安装~wget http://redis.googlecode.com/files/redis-2.2.13.tar.gz tar -zxf redis-2.2.13.tar.gz cd redis-2.2.13 make make install keepalived的安装~tar -xzvf keepalived-1.1.20.tar.gz cd keepalived-1.1.20 ./configure --prefix=/usr/local/webserver/keepalived make make install cp /usr/local/webserver/keepalived/sbin/keepalived /usr/sbin cp /usr/local/webserver/keepalived/etc/sysconfig/keepalived /etc/sysconfig cp /usr/local/webserver/keepalived/etc/rc.d/init.d/keepalived /etc/init.d mkdir /etc/keepalived cp /usr/local/webserver/keepalived/etc/keepalived/keepalived.conf /etc/keepalived 安装完之后，具体说下高可用性的部分，下面是 主的keepalived.conf 的配置文件~ 用killall -0 redis-server 来判断进程的存活~也可以用checkredis.sh 这个脚本~【大家可以写简单点~】 这个方法是redis自带的一个判断服务存活的程序#!/bin/bash REDIS_HOME="/home/redis" REDIS_COMMANDS="/home/redis/src" # The location of the redis binary REDIS_MASTER_IP="172.16.0.180" # Redis MASTER ip REDIS_MASTER_PORT="6379" # Redis MASTER port ERROR_MSG=`${REDIS_COMMANDS}/redis-cli PING` # # Check the output for PONG. # if [ "$ERROR_MSG" != "PONG" ] then # redis is down, return http 503 /bin/echo -e "HTTP/1.1 503 Service Unavailable/r/n" /bin/echo -e "Content-Type: Content-Type: text/plain/r/n" /bin/echo -e "/r/n" /bin/echo -e "Redis is *down*./r/n" /bin/echo -e "/r/n" exit 1 else # redis is fine, return http 200 /bin/echo -e "HTTP/1.1 200 OK/r/n" /bin/echo -e "Content-Type: Content-Type: text/plain/r/n" /bin/echo -e "/r/n" /bin/echo -e "Redis is running./r/n" /bin/echo -e "/r/n" exit 0 fi 在变为backup的状态下，所运行的服务，为主的时候所运行的服务~global_defs { router_id DBPOOL_01 } vrrp_script chk_redis { script "killall -0 redis-server" interval 2 } vrrp_instance VI_ETH0 { interface eth0 virtual_router_id 100 nopreempt priority 200 advert_int 1 state BACKUP track_script { chk_redis } virtual_ipaddress { 172.16.0.180 } notify_master "/opt/redis.sh -m" notify_backup "/opt/redis.sh -s" notify_fault "/opt/redis.sh -k" } 下面是从的配置global_defs { router_id DBPOOL_01 } vrrp_script chk_redis { script "killall -0 redis-server" interval 2 } vrrp_instance VI_ETH0 { interface eth0 virtual_router_id 100 nopreempt priority 100 advert_int 1 state BACKUP track_script { chk_redis } virtual_ipaddress { 172.16.0.180 } notify_master "/opt/redis.sh -m" notify_backup "/opt/redis.sh -s" notify_fault "/opt/redis.sh -k" } 下面是 /opt/redis.sh 的脚本#!/bin/sh # # Script to start Redis and promote to MASTER/SLAVE # Usage Options: # -m promote the redis-server to MASTER # -s promote the redis-server to SLAVE # -k start the redis-server and promote it to MASTER # REDIS_HOME="/home/redis" REDIS_COMMANDS="/home/redis/src" # redis执行文件的目录 REDIS_MASTER_IP="172.16.0.180" # Redis MASTER ip REDIS_MASTER_PORT="6379" # Redis MASTER port REDIS_CONF="redis-mdb.conf" # 配置文件 E_INVALID_ARGS=65 E_INVALID_COMMAND=66 E_NO_SLAVES=67 E_DB_PROBLEM=68 error() { E_CODE=$? echo "Exiting: ERROR ${E_CODE}: $E_MSG" exit $E_CODE } start_redis() { alive=`${REDIS_COMMANDS}/redis-cli PING` if [ "$alive" != "PONG" ]; then ${REDIS_COMMANDS}/redis-server ${REDIS_HOME}/${REDIS_CONF} sleep 1 fi } start_master() { ${REDIS_COMMANDS}/redis-cli SLAVEOF no one } start_slave() { ${REDIS_COMMANDS}/redis-cli SLAVEOF ${REDIS_MASTER_IP} ${REDIS_MASTER_PORT} } usage() { echo -e "Start Redis and promote to MASTER/SLAVE - version 0.3 (c) Alex Williams - www.alexwilliams.ca" echo -e "/nOptions: " echo -e "/t-m/tpromote the redis-server to MASTER" echo -e "/t-s/tpromote the redis-server to SLAVE" echo -e "/t-k/tstart the redis-server and promote it to MASTER" echo -e "" exit $E_INVALID_ARGS } for arg in "$@" do case $arg in -m) arg_m=true;; -s) arg_s=true;; -k) arg_k=true;; *) usage;; esac done if [ $arg_m ]; then echo -e "Promoting redis-server to MASTER/n" start_redis wait start_master elif [ $arg_s ]; then echo -e "Promoting redis-server to SLAVE/n" start_redis wait start_slave elif [ $arg_k ]; then echo -e "Starting redis-server and promoting to MASTER/n" start_redis wait start_master else usage fi
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