在生产场景下都必须做到高可用，否则出现问题就会造成服务停止。这里介绍下Redis的Sentinel功能实现的高可用，当然也有Redis提供的cluster功能。
1.Redis的安装
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wget http:
//download
.redis.io
/releases/redis-3
.0.7.
tar
.gz
tar
zxf redis-3.0.7.
tar
.gz
cd
redis-3.0.7
make
cd
src
mkdir
-p
/usr/local/redis3
.0.7/{sbin,data,conf}
scp
-r mkreleasehdr.sh redis-benchmark redis-check-aof redis-check-dump redis-cli redis-sentinel redis-server localhost:
/usr/local/redis3
.0.7
/sbin
cp
..
/redis
.conf
/usr/local/redis3
.0.7
/conf/
echo
'PATH=$PATH:/usr/local/redis3.0.7/sbin'
>>
/etc/profile
source
/etc/profile
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2.Redis的配置
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vim
/usr/local/redis3
.0.7
/conf/redis
.conf
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(以下为db1的配置,db2的配置只需要增加一行slaveof 192.168.2.241 6379)
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#是否以服务方式开启
daemonize no
pidfile
/var/run/redis
.pid
#端口
port 6379
tcp-backlog 511
timeout 0
tcp-keepalive 0
#日志提醒级别
loglevel notice
#日志文件路径
logfile
""
#数据库数量
databases 16
#日志刷新策略（Master禁用）
save 900 1
#说明900秒内1次改动，自动保存一次数据集
save 300 10
save 60 10000
stop-writes-on-bgsave-error
yes
#以rdb方式存储时是否压缩
rdbcompression
yes
#rdb是否校验
rdbchecksum
yes
#数据文件名
dbfilename dump.rdb
#数据文件路径
dir
/usr/local/redis3
.0.7
/data
slave-serve-stale-data
yes
#从服务器只读
slave-
read
-only
yes
#指定与主数据库连接时需要的密码验证，主库无需设置
#masterauth
#masterauth
repl-diskless-
sync
no
repl-diskless-
sync
-delay 5
repl-disable-tcp-nodelay no
slave-priority 100
##启用增量（Master禁用）
appendonly no
#增量日志文件名，默认值为appendonly.aof
appendfilename
"appendonly.aof"
#设置对 appendonly.aof 文件进行同步的频率
#always 表示每次有写操作都进行同步,everysec 表示对写操作进行累积,每秒同步一次。
#no表示等操作系统进行数据缓存同步到磁盘，都进行同步,everysec 表示对写操作进行累#积,每秒同步一次
appendfsync everysec
no-appendfsync-on-rewrite no
auto-aof-rewrite-percentage 100
auto-aof-rewrite-min-size 64mb
aof-load-truncated
yes
lua-
time
-limit 5000
slowlog-log-slower-than 10000
slowlog-max-len 128
latency-monitor-threshold 0
notify-keyspace-events
""
hash
-max-ziplist-entries 512
hash
-max-ziplist-value 64
list-max-ziplist-entries 512
list-max-ziplist-value 64
set
-max-intset-entries 512
zset-max-ziplist-entries 128
zset-max-ziplist-value 64
hll-sparse-max-bytes 3000
activerehashing
yes
client-output-buffer-limit normal 0 0 0
client-output-buffer-limit slave 256mb 64mb 60
client-output-buffer-limit pubsub 32mb 8mb 60
hz 10
aof-rewrite-incremental-fsync
yes
#最大可用内存
#maxmemory 2mb
#配置成从服务器
#slaveof 192.168.2.250 6379
#客户端连接访问口令
# requirepass foobared
#限制同时连接的客户数量，防止过多的client导致内存耗尽。如果有足够内存可以不进行#设置
#maxclients 10000
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3.Sentinel的配置
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vim
/usr/local/redis3
.0.7
/conf/sentinel
.conf
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port 26379
sentinel monitor master 192.168.2.241 6379 2
sentinel down-after-milliseconds master 5000
sentinel failover-timeout master 900000
#sentinel can-failover master yes
sentinel parallel-syncs master 2
# Generated by CONFIG REWRITE
dir
"/usr/local/redis3.0.7/conf"
#sentinel client-reconfig-script master /usr/local/redis3.0.7/sbin/vip.sh
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4.启动redis-server及redis-sentinel
在db1,db2,db3上分别启动redis-server及redis-sentinel
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2
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/usr/local/redis3
.0.7
/sbin/redis-server
/usr/local/redis3
.0.7
/conf/redis
.conf
/usr/local/redis3
.0.7
/sbin/redis-sentinel
/usr/local/redis3
.0.7
/conf/sentinel
.conf
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这个时候就已经做好了Redis的主从复制及故障转移，我们客户端的连接就需要修改，因此就涉及到VIP的问题，客户端只要连接VIP的问题，目前VIP的解决方法有
-
利用redis-sentinel的sentinel client-reconfig-script参数进行设置
-
利用keepalived进行VIP的转移
-
利用consul进行服务注册
a.利用redis-sentinel自带的参数进行VIP的配置
在db1,db2的sentinel.conf中加入
sentinel client-reconfig-script master1 /usr/local/redis3.0.7/sbin/vip.sh
然后创建脚本/usr/local/redis3.0.7/sbin/vip.sh
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#!/bin/bash
MASTER_IP=$6
LOCAL_IP=
'192.168.2.241'
#从库修改为192.168.2.242
VIP=
'192.168.2.250'
NETMASK=
'24'
INTERFACE=
'eth0'
if
[ ${MASTER_IP} = ${LOCAL_IP} ];
then
/sbin/ip
addr add ${VIP}/${NETMASK} dev ${INTERFACE}
/sbin/arping
-q -c 3 -A ${VIP} -I ${INTERFACE}
exit
0
else
/sbin/ip
addr del ${VIP}/${NETMASK} dev ${INTERFACE}
exit
0
fi
exit
1
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在集群启动的时候需要手动添加VIP
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/sbin/ip
addr add 192.168.2.250
/24
dev eth0
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使用上面脚本的时候需要注意你的网卡是eth0，否则可能出现VIP无法使用的情况
b.利用keepalived进行VIP的切换
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wget http:
//www
.keepalived.org
/software/keepalived-1
.2.19.
tar
.gz
tar
zxf keepalived-1.2.19.
tar
.gz
cd
keepalived-1.2.19
.
/configure
--prefix=
/usr/local/keepalived1
.2.19 --disable-fwmark
make
&&
make
install
ln
-s
/usr/local/keepalived1
.2.19
/sbin/keepalived
/usr/sbin/
ln
-s
/usr/local/keepalived1
.2.19
/etc/sysconfig/keepalived
/etc/sysconfig/
ln
-s
/usr/local/keepalived1
.2.19
/etc/keepalived/
/etc/keepalived
ln
-s
/usr/local/keepalived1
.2.19
/etc/rc
.d
/init
.d
/keepalived
/etc/init
.d/
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db1的keepalived配置文件
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! Configuration File
for
keepalived
global_defs {
notification_email {
root@localhost
}
notification_email_from keepalived@localhost
smtp_server 127.0.0.1
smtp_connect_timeout 10
router_id keepalivedha_1
}
vrrp_script chk_redis_role {
script
"/usr/local/redis3.0.7/sbin/redis-cli info | grep role:master >/dev/null 2>&1"
interval 1
timeout 2
fall 2
rise 1
}
vrrp_sync_group VG_1 {
group {
VI_1
}
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
#use_vmac keepalived
#vmac_xmit_base
smtp_alert
virtual_router_id 20
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass password
}
virtual_ipaddress {
192.168.2.250
}
track_script {
chk_redis_role
}
}
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db2的配置文件，只需要将以上文件复制过来并修改下面参数
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priority 98
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#注意一下interface eth0看下你机器的网卡接口
c.利用consul服务注册
参考:http://dgd2010.blog.51cto.com/1539422/1745314
从上面可以看出以上三种方法:
脚本跟keepalived的形式一样，但是脚本相对轻量,首次启动麻烦，配置简单，依赖于redis-sentinel
keepalived启动简单，排错简便
consul适合大型场景，及云环境没有多余的IP这种情况
以上也适用于2台服务器的场景，也可以不用3台服务器。只需要更改
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sentinel monitor master 192.168.2.241 6379 1
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后面值更改为1即可
本文转自 rong341233 51CTO博客，原文链接:http://blog.51cto.com/fengwan/1746731
