Redis安装及主从配置
Redis安装及主从配置
Redis是一种面向“键/值”对类型数据的分布式NoSQL数据库系统,特点是高性能,持久存储,适应高并发的应用场景。它起步较晚,发展迅速,目前已被许多大型机构采用,如google、taobao、sina微博等。本文不对其数据结构做深入的讲解,只是介绍其安装及主从结构的配置过程。如需要更详细的了解请参考其官方网站。Redis的安装
Redis目前只支持Linux及BSD等系统,不支持Window下的安装。在Linux下安装的过程如下所示:
$ wget http://redis.googlecode.com/files/redis-2.2.12.tar.gz $ tar xzf redis-2.2.12.tar.gz $ cd redis-2.2.12 $ make |
安装成功后的提示为:
Hint: To run 'make test' is a good idea ;) make[1]: Leaving directory `/usr/alibaba/install/redis-2.2.12/src' |
在安装完成后,即可进入至该工程的src下启动服务:
$ src/redis-server |
通过内置的build-cli工具进行相应的测试,其测试过程如下:
$ src/redis-cli redis> set foo bar OK redis> get foo "bar" redis > getset foo 123 “bar” redis >get foo 123 |
Redis的主从配置
机器的分配
主从结构的配置所涉及到的机器及各机器所完成的功能如下所示:
IP地址 |
角色 |
10.20.150.205 |
主结点 |
10.20.150.208 |
从结点1 |
10.20.150.209 |
从结点2 |
主从结构的配置
在进行主从结构配置之前,请确保已经在上述三台机器上已经安装了Redis服务。对于Redis的主从结构的配置相对比较简单,只需修改redis.conf文件,配置上主结点对应的IP及端口。具体如下所示:
Port 6380 bind 10.20.150.205 slaveof 10.20.150.205 6379 |
l port 6380表示当前该Redis服务对应的端口号;
l bind 10.20.150.205 表示当前Redis绑定的主结点的IP地址;
l slaveof 10.20.150.205 6379 表示当前Redis是哪个主结点的从结点,其中包括IP及端口号。
当主结点在启动时
当只有一台主结点在启动时,会显示如下的信息:
[29028] 26 Sep 18:39:12 * Server started, Redis version 2.2.12 [29028] 26 Sep 18:39:12 # WARNING 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. [29028] 26 Sep 18:39:12 * DB loaded from disk: 0 seconds [29028] 26 Sep 18:39:12 * The server is now ready to accept connections on port 6379 [29028] 26 Sep 18:39:12 - 0 clients connected (0 slaves), 790584 bytes in use |
当有一台从结点10.20.150.208启动时
其中主结点会自动检测到有新的从结点启动并加入进来,其显示的信息如下:
[29028] 26 Sep 18:40:31 - Accepted 10.20.150.208:44779 [29028] 26 Sep 18:40:31 * Slave ask for synchronization [29028] 26 Sep 18:40:31 * Starting BGSAVE for SYNC [29028] 26 Sep 18:40:31 * Background saving started by pid 29091 [29091] 26 Sep 18:40:31 * DB saved on disk [29028] 26 Sep 18:40:31 * Background saving terminated with success [29028] 26 Sep 18:40:31 * Synchronization with slave succeeded [29028] 26 Sep 18:40:32 - 0 clients connected (1 slaves), 798752 bytes in use [29028] 26 Sep 18:40:37 - 0 clients connected (1 slaves), 798752 bytes in use [29028] 26 Sep 18:40:42 - 0 clients connected (1 slaves), 798752 bytes in use [29028] 26 Sep 18:40:47 - 0 clients connected (1 slaves), 798752 bytes in use |
对于从结点显示的信息如下:
#[597] 26 Sep 18:40:29 * Server started, Redis version 2.2.12 [597] 26 Sep 18:40:29 # WARNING 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. [597] 26 Sep 18:40:29 * The server is now ready to accept connections on port 6379 [597] 26 Sep 18:40:29 - 0 clients connected (0 slaves), 790616 bytes in use [597] 26 Sep 18:40:29 * Connecting to MASTER... [597] 26 Sep 18:40:29 * MASTER <-> SLAVE sync started: SYNC sent [597] 26 Sep 18:40:29 * MASTER <-> SLAVE sync: receiving 10 bytes from master [597] 26 Sep 18:40:29 * MASTER <-> SLAVE sync: Loading DB in memory [597] 26 Sep 18:40:29 * MASTER <-> SLAVE sync: Finished with success [597] 26 Sep 18:40:34 - 1 clients connected (0 slaves), 798744 bytes in use |
当有另外一台从机10.20.150.209挂载时
当有另一台从机挂载至主机时,主机显示的信息如下:
[29028] 26 Sep 18:42:52 - 0 clients connected (1 slaves), 798752 bytes in use [29028] 26 Sep 18:42:57 - 0 clients connected (1 slaves), 798752 bytes in use [29028] 26 Sep 18:42:58 - Accepted 10.20.150.209:47650 [29028] 26 Sep 18:42:58 * Slave ask for synchronization [29028] 26 Sep 18:42:58 * Starting BGSAVE for SYNC [29028] 26 Sep 18:42:58 * Background saving started by pid 29287 [29287] 26 Sep 18:42:58 * DB saved on disk [29028] 26 Sep 18:42:59 * Background saving terminated with success [29028] 26 Sep 18:42:59 * Synchronization with slave succeeded [29028] 26 Sep 18:43:02 - 0 clients connected (2 slaves), 806920 bytes in use |
从另一台从机上可以看到的信息如下:
[Intranet root@xasc-150-209 /usr/alibaba/install/redis-2.2.12/src] #./redis-server ../redis.conf [15034] 26 Sep 18:42:56 * Server started, Redis version 2.2.12 [15034] 26 Sep 18:42:56 # WARNING 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. [15034] 26 Sep 18:42:56 * The server is now ready to accept connections on port 6379 [15034] 26 Sep 18:42:56 - 0 clients connected (0 slaves), 790616 bytes in use [15034] 26 Sep 18:42:56 * Connecting to MASTER... [15034] 26 Sep 18:42:56 * MASTER <-> SLAVE sync started: SYNC sent [15034] 26 Sep 18:42:56 * MASTER <-> SLAVE sync: receiving 10 bytes from master [15034] 26 Sep 18:42:56 * MASTER <-> SLAVE sync: Loading DB in memory [15034] 26 Sep 18:42:56 * MASTER <-> SLAVE sync: Finished with success [15034] 26 Sep 18:43:01 - 1 clients connected (0 slaves), 798744 bytes in use |
当主结点宕掉时
当主结点突然间不可用,两台从机会由于找不到主结点而报错,信息如下:
[597] 26 Sep 18:46:09 * Connecting to MASTER... [597] 26 Sep 18:46:09 # Unable to connect to MASTER: Connection refused [597] 26 Sep 18:46:10 * Connecting to MASTER... [597] 26 Sep 18:46:10 # Unable to connect to MASTER: Connection refused [597] 26 Sep 18:46:11 * Connecting to MASTER... [597] 26 Sep 18:46:11 # Unable to connect to MASTER: Connection refused [597] 26 Sep 18:46:12 * Connecting to MASTER... [597] 26 Sep 18:46:12 # Unable to connect to MASTER: Connection refused [597] 26 Sep 18:46:13 * Connecting to MASTER... [597] 26 Sep 18:46:13 # Unable to connect to MASTER: Connection refused [597] 26 Sep 18:46:14 - 0 clients connected (0 slaves), 790616 bytes in use |
主结点在没有启动的情况下,从机先启动时
当主结点还没有启动时,从结点先启动,由于找不到对应主结点,会报如下的信息错误:
[Intranet root@xasc-150-208 /usr/alibaba/install/redis-2.2.12/src] #./redis-server ../redis.conf [1842] 26 Sep 18:48:50 * Server started, Redis version 2.2.12 [1842] 26 Sep 18:48:50 # WARNING 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. [1842] 26 Sep 18:48:50 * DB loaded from disk: 0 seconds [1842] 26 Sep 18:48:50 * The server is now ready to accept connections on port 6379 [1842] 26 Sep 18:48:50 - 0 clients connected (0 slaves), 790616 bytes in use [1842] 26 Sep 18:48:50 * Connecting to MASTER... [1842] 26 Sep 18:48:50 # Unable to connect to MASTER: Connection refused [1842] 26 Sep 18:48:51 * Connecting to MASTER... [1842] 26 Sep 18:48:51 # Unable to connect to MASTER: Connection refused [1842] 26 Sep 18:48:52 * Connecting to MASTER... [1842] 26 Sep 18:48:52 # Unable to connect to MASTER: Connection refused [1842] 26 Sep 18:48:53 * Connecting to MASTER... [1842] 26 Sep 18:48:53 # Unable to connect to MASTER: Connection refused [1842] 26 Sep 18:48:54 * Connecting to MASTER... [1842] 26 Sep 18:48:54 # Unable to connect to MASTER: Connection refused [1842] 26 Sep 18:48:55 - 0 clients connected (0 slaves), 790616 bytes in use |
当有一台从机不可用时
当有一台从机变得不可用时,主机显示的信息如下:
32 - 1 clients connected (0 slaves), 798744 bytes in use [16848] 26 Sep 18:50:37 - 1 clients connected (0 slaves), 798744 bytes in use [16848] 26 Sep 18:50:42 - 1 clients connected (0 slaves), 798744 bytes in use |
当两台从机都宕掉时
当两台从机都变得不可用时,主机显示的信息如下:
[29736] 26 Sep 18:52:57 - Client closed connection [29736] 26 Sep 18:53:02 - 0 clients connected (0 slaves), 790584 bytes in use [29736] 26 Sep 18:53:07 - 0 clients connected (0 slaves), 790584 bytes in use |
主从结构的测试
在主结点上执行写入
在主机上执行写入命令1
redis> set foo bar |
在各个从机上会显示的信息如下:
[2528] 26 Sep 18:57:01 - DB 0: 1 keys (0 volatile) in 4 slots HT. [2528] 26 Sep 18:57:01 - 1 clients connected (0 slaves), 798952 bytes in use [2528] 26 Sep 18:57:06 - DB 0: 1 keys (0 volatile) in 4 slots HT. [2528] 26 Sep 18:57:06 - 1 clients connected (0 slaves), 798936 bytes in use |
在主机上执行get foo命令,显示的信息如下:
redis 127.0.0.1:6379> get foo "bar" |
在从机10.20.150.208上执行get foo命令,显示的信息如下:
redis 127.0.0.1:6379> get foo "bar" |
同理,在从机10.20.150.209上执行get foo命令,显示的信息如下:
redis 127.0.0.1:6379> get foo "bar" |
当有一台从机挂掉后,在主机上写入
当有一台从机(10.20.150.208)宕机,在主机上执行setfoo1写入命令。
主机上执行get foo1时显示的信息如下:
redis 127.0.0.1:6379> get foo1 "test" |
另一台从机上执行getfoo1时显示的信息如下:
redis 127.0.0.1:6379> get foo1 "test" |
当把10.20.150.208从机启动起来时,执行getfoo1命令,显示的信息如下:
redis 127.0.0.1:6379> get foo1 "test" |
可见,即使当从机挂掉并再次启动时,仍会将主机做过的修改全部都同步至重启的从机上。
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