Redis 主从复制

redis主从复制过程：当配置好slave后，slave与master建立连接，然后发送sync命令。无论是第一次连接还是重新连接，master都会启动一个后台进程，将数据库快照保存到文件中，同时master主进程会开始收集新的写命令并缓存。后台进程完成写文件后，master就发送文件给slave，slave将文件保存到硬盘上，再加载到内存中，接着master就会把缓存的命令转发给slave，后续master将收到的写命令发送给slave。如果master同时收到多个slave发来的同步连接命令，master只会启动一个进程来写数据库镜像，然后发送给所有的slave。 

单机上配置实例：

master   localhost 6379

slave1   localhost 6378

slave2   localhost 6377

配置：

在2个slave的配置文件中 添加slaveof localhost 6379

分别启动 master  slave1 slave2

使用info命令查看各服务器信息

 

redis 127.0.0.1:6379> info

redis_version:2.4.5

redis_git_sha1:00000000

redis_git_dirty:0

arch_bits:32

multiplexing_api:winsock2

process_id:968

uptime_in_seconds:513

uptime_in_days:0

lru_clock:1957753

used_cpu_sys:0.23

used_cpu_user:0.08

used_cpu_sys_children:0.00

used_cpu_user_children:0.00

connected_clients:1

connected_slaves:2 slave的数目

client_longest_output_list:0

client_biggest_input_buf:0

blocked_clients:0

used_memory:696660

used_memory_human:680.33K

used_memory_rss:696660

used_memory_peak:696628

used_memory_peak_human:680.30K

mem_fragmentation_ratio:1.00

mem_allocator:libc

loading:0

aof_enabled:0

changes_since_last_save:0

bgsave_in_progress:0

last_save_time:1340783219

bgrewriteaof_in_progress:0

total_connections_received:121

total_commands_processed:5

expired_keys:0

evicted_keys:0

keyspace_hits:0

keyspace_misses:0

pubsub_channels:0

pubsub_patterns:0

latest_fork_usec:0

vm_enabled:0

role:master   说明该服务器为master

 

 

 

 

redis 127.0.0.1:6378> info

redis_version:2.4.5

redis_git_sha1:00000000

redis_git_dirty:0

arch_bits:32

multiplexing_api:winsock2

process_id:7056

uptime_in_seconds:543

uptime_in_days:0

lru_clock:1957789

used_cpu_sys:0.02

used_cpu_user:0.03

used_cpu_sys_children:0.00

used_cpu_user_children:0.00

connected_clients:2

connected_slaves:0

client_longest_output_list:0

client_biggest_input_buf:0

blocked_clients:0

used_memory:688592

used_memory_human:672.45K

used_memory_rss:688592

used_memory_peak:688560

used_memory_peak_human:672.42K

mem_fragmentation_ratio:1.00

mem_allocator:libc

loading:0

aof_enabled:0

changes_since_last_save:0

bgsave_in_progress:0

last_save_time:1340783116

bgrewriteaof_in_progress:0

total_connections_received:1

total_commands_processed:55

expired_keys:0

evicted_keys:0

keyspace_hits:0

keyspace_misses:0

pubsub_channels:0

pubsub_patterns:0

latest_fork_usec:0

vm_enabled:0

role:slave

master_host:localhost

master_port:6379

master_link_status:up  up说明连接master良好，down则是连接失败

master_last_io_seconds_ago:1 

master_sync_in_progress:0

 

 

测试：

 

redis 127.0.0.1:6379> set name wilian

OK

redis 127.0.0.1:6379> get name

"wilian"

 

 

redis 127.0.0.1:6378> get name

"wilian"

 

redis 127.0.0.1:6377> get name

"wilian"

 

同步成功！