Redis主从
1. 介绍¶
REmote DIctionary Server(Redis) 是一个由Salvatore Sanfilippo写的key-value存储系统。
Redis是一个开源的使用ANSI C语言编写、遵守BSD协议、支持网络、可基于内存亦可持久化的日志型、Key-Value数据库，并提供多种语言的API。
它通常被称为数据结构服务器，因为值（value）可以是 字符串(String), 哈希(Hash), 列表(list), 集合(sets) 和 有序集合(sorted sets)等类型。
2. 部署¶
2.1 Redis 主从¶
Redis支持主从同步。数据可以从主服务器向任意数量的从服务器上同步，同步使用的是发布/订阅机制。
2.2 配置¶
Mater Slave的模式，从Slave向Master发起SYNC命令。
Master 多Slave，可以分层，Slave下可以再接Slave，可扩展成树状结构。
配置非常简单，只需在slave的设定文件中指定master的ip和port
root@leco:/usr/local/redis# mkdir redis1/{etc,var,log} -p
root@leco:/usr/local/redis# tree .
.
└── redis1
├── etc
├── log
└── var
4 directories, 0 files
root@leco:/usr/local/redis# cp -aR redis1/ redis2
root@leco:/usr/local/redis# vim redis1/etc/redis.conf
root@leco:/usr/local/redis# cat redis1/etc/redis.conf
2.3 master配置¶
root@leco:/usr/local/redis# cat redis1/etc/redis.conf daemonize yes pidfile "/usr/local/redis/redis1/log/redis.pid" port 8379 timeout 300 loglevel debug logfile "/usr/local/redis/redis1/log/redis.log" databases 16 save 900 1 save 300 10 save 60 10000 rdbcompression yes dbfilename "dump.rdb" dir "/usr/local/redis/redis1/var" appendonly no appendfsync always bind 0.0.0.0
2.4 slave配置¶
root@leco:/usr/local/redis# cat redis2/etc/redis.conf daemonize yes pidfile "/usr/local/redis/redis1/log/redis.pid" port 8380 timeout 300 loglevel debug logfile "/usr/local/redis/redis1/log/redis.log" databases 16 save 900 1 save 300 10 save 60 10000 rdbcompression yes dbfilename "dump.rdb" dir "/usr/local/redis/redis1/var" appendonly no appendfsync always bind 0.0.0.0 slaveof 172.17.0.2 8379
手动配置主
在从上配置要同步的主 127.0.0.1:8380> slaveof localhost 6380
只读模式
slave-read-only yes 设置slave为只读模式
2.5 启动¶
root@leco:/usr/local/redis# redis-server /usr/local/redis/redis1/etc/redis.conf root@leco:/usr/local/redis# redis-server /usr/local/redis/redis2/etc/redis.conf root@leco:/usr/local/redis# ps axf|egrep '8379|8380' | grep -v grep 5796 ? Ssl 0:00 redis-server 0.0.0.0:8379 6663 ? Ssl 0:00 redis-server 0.0.0.0:8380
2.6 检查主从¶
root@leco:/usr/local/redis# redis-cli -p 8379 127.0.0.1:8379> keys * (empty list or set) 127.0.0.1:8379> set name 'cmz' OK 127.0.0.1:8379> quit root@leco:/usr/local/redis# redis-cli -p 8380 127.0.0.1:8380> keys* (error) ERR unknown command 'keys*' 127.0.0.1:8380> keys * 1) "name" 127.0.0.1:8380> get name "cmz" root@leco:/usr/local/redis# redis-cli -p 8379 127.0.0.1:8379> info # Server redis_version:3.0.6 redis_git_sha1:00000000 redis_git_dirty:0 redis_build_id:28b6715d3583bf8e redis_mode:standalone os:Linux 4.15.0-45-generic x86_64 arch_bits:64 multiplexing_api:epoll gcc_version:5.4.0 process_id:5796 run_id:32ac4a621301f8c8398439b074ff3cf7b7e0d0f9 tcp_port:8379 uptime_in_seconds:557 uptime_in_days:0 hz:10 lru_clock:7649260 config_file:/usr/local/redis/redis1/etc/redis.conf # Clients connected_clients:1 client_longest_output_list:0 client_biggest_input_buf:0 blocked_clients:0 # Memory used_memory:1884808 used_memory_human:1.80M used_memory_rss:3731456 used_memory_peak:1884808 used_memory_peak_human:1.80M used_memory_lua:36864 mem_fragmentation_ratio:1.98 mem_allocator:jemalloc-3.6.0 # Persistence loading:0 rdb_changes_since_last_save:1 rdb_bgsave_in_progress:0 rdb_last_save_time:1551152980 rdb_last_bgsave_status:ok rdb_last_bgsave_time_sec:0 rdb_current_bgsave_time_sec:-1 aof_enabled:0 aof_rewrite_in_progress:0 aof_rewrite_scheduled:0 aof_last_rewrite_time_sec:-1 aof_current_rewrite_time_sec:-1 aof_last_bgrewrite_status:ok aof_last_write_status:ok # Stats total_connections_received:4 total_commands_processed:158 instantaneous_ops_per_sec:0 total_net_input_bytes:5511 total_net_output_bytes:318 instantaneous_input_kbps:0.02 instantaneous_output_kbps:0.00 rejected_connections:0 sync_full:1 sync_partial_ok:0 sync_partial_err:0 expired_keys:0 evicted_keys:0 keyspace_hits:0 keyspace_misses:0 pubsub_channels:0 pubsub_patterns:0 latest_fork_usec:154 migrate_cached_sockets:0 # Replication role:master connected_slaves:1 slave0:ip=127.0.0.1,port=8380,state=online,offset=266,lag=1 master_repl_offset:266 repl_backlog_active:1 repl_backlog_size:1048576 repl_backlog_first_byte_offset:2 repl_backlog_histlen:265 # CPU used_cpu_sys:0.40 used_cpu_user:0.11 used_cpu_sys_children:0.00 used_cpu_user_children:0.00 # Cluster cluster_enabled:0 # Keyspace db0:keys=1,expires=0,avg_ttl=0
2.7 查看slave¶
在主上执行 info repliaction
127.0.0.1:8379> INFO replication # Replication role:master connected_slaves:1 slave0:ip=127.0.0.1,port=8380,state=online,offset=308,lag=0 master_repl_offset:308 repl_backlog_active:1 repl_backlog_size:1048576 repl_backlog_first_byte_offset:2 repl_backlog_histlen:307
2.8 手动切换身份¶
Master不可用的情况下，停止Master，将Slave的设定无效化后，Slave升级为Master
root@leco:/usr/local/redis# redis-cli -p 8380 127.0.0.1:8380> info # Server redis_version:3.0.6 redis_git_sha1:00000000 redis_git_dirty:0 redis_build_id:28b6715d3583bf8e redis_mode:standalone os:Linux 4.15.0-45-generic x86_64 arch_bits:64 multiplexing_api:epoll gcc_version:5.4.0 process_id:7666 run_id:5e077def1cd19dee9f3a379cc889b363f20b8305 tcp_port:8380 uptime_in_seconds:64 uptime_in_days:0 hz:10 lru_clock:7649736 config_file:/usr/local/redis/redis2/etc/redis.conf # Clients connected_clients:2 client_longest_output_list:0 client_biggest_input_buf:0 blocked_clients:0 # Memory used_memory:837232 used_memory_human:817.61K used_memory_rss:3686400 used_memory_peak:837232 used_memory_peak_human:817.61K used_memory_lua:36864 mem_fragmentation_ratio:4.40 mem_allocator:jemalloc-3.6.0 # Persistence loading:0 rdb_changes_since_last_save:0 rdb_bgsave_in_progress:0 rdb_last_save_time:1551153544 rdb_last_bgsave_status:ok rdb_last_bgsave_time_sec:-1 rdb_current_bgsave_time_sec:-1 aof_enabled:0 aof_rewrite_in_progress:0 aof_rewrite_scheduled:0 aof_last_rewrite_time_sec:-1 aof_current_rewrite_time_sec:-1 aof_last_bgrewrite_status:ok aof_last_write_status:ok # Stats total_connections_received:3 total_commands_processed:4 instantaneous_ops_per_sec:0 total_net_input_bytes:130 total_net_output_bytes:1540 instantaneous_input_kbps:0.00 instantaneous_output_kbps:0.04 rejected_connections:0 sync_full:0 sync_partial_ok:0 sync_partial_err:0 expired_keys:0 evicted_keys:0 keyspace_hits:0 keyspace_misses:0 pubsub_channels:0 pubsub_patterns:0 latest_fork_usec:0 migrate_cached_sockets:0 # Replication role:slave # 是从 master_host:127.0.0.1 master_port:8379 master_link_status:up master_last_io_seconds_ago:6 master_sync_in_progress:0 slave_repl_offset:43 slave_priority:100 slave_read_only:1 connected_slaves:0 master_repl_offset:0 repl_backlog_active:0 repl_backlog_size:1048576 repl_backlog_first_byte_offset:0 repl_backlog_histlen:0 # CPU used_cpu_sys:0.06 used_cpu_user:0.01 used_cpu_sys_children:0.00 used_cpu_user_children:0.00 # Cluster cluster_enabled:0 # Keyspace db0:keys=1,expires=0,avg_ttl=0 127.0.0.1:8380> SLAVEOF no one 配置没有主 OK 127.0.0.1:8380> info # Server redis_version:3.0.6 redis_git_sha1:00000000 redis_git_dirty:0 redis_build_id:28b6715d3583bf8e redis_mode:standalone os:Linux 4.15.0-45-generic x86_64 arch_bits:64 multiplexing_api:epoll gcc_version:5.4.0 process_id:7666 run_id:5e077def1cd19dee9f3a379cc889b363f20b8305 tcp_port:8380 uptime_in_seconds:103 uptime_in_days:0 hz:10 lru_clock:7649775 config_file:/usr/local/redis/redis2/etc/redis.conf # Clients connected_clients:1 client_longest_output_list:0 client_biggest_input_buf:0 blocked_clients:0 # Memory used_memory:816360 used_memory_human:797.23K used_memory_rss:3686400 used_memory_peak:837232 used_memory_peak_human:817.61K used_memory_lua:36864 mem_fragmentation_ratio:4.52 mem_allocator:jemalloc-3.6.0 # Persistence loading:0 rdb_changes_since_last_save:0 rdb_bgsave_in_progress:0 rdb_last_save_time:1551153544 rdb_last_bgsave_status:ok rdb_last_bgsave_time_sec:-1 rdb_current_bgsave_time_sec:-1 aof_enabled:0 aof_rewrite_in_progress:0 aof_rewrite_scheduled:0 aof_last_rewrite_time_sec:-1 aof_current_rewrite_time_sec:-1 aof_last_bgrewrite_status:ok aof_last_write_status:ok # Stats total_connections_received:3 total_commands_processed:11 instantaneous_ops_per_sec:0 total_net_input_bytes:268 total_net_output_bytes:4961 instantaneous_input_kbps:0.00 instantaneous_output_kbps:0.00 rejected_connections:0 sync_full:0 sync_partial_ok:0 sync_partial_err:0 expired_keys:0 evicted_keys:0 keyspace_hits:0 keyspace_misses:0 pubsub_channels:0 pubsub_patterns:0 latest_fork_usec:0 migrate_cached_sockets:0 # Replication role:master # 变成了master了 connected_slaves:0 master_repl_offset:99 repl_backlog_active:0 repl_backlog_size:1048576 repl_backlog_first_byte_offset:0 repl_backlog_histlen:0 # CPU used_cpu_sys:0.09 used_cpu_user:0.02 used_cpu_sys_children:0.00 used_cpu_user_children:0.00 # Cluster cluster_enabled:0 # Keyspace db0:keys=1,expires=0,avg_ttl=0 127.0.0.1:8380>
2.9 健康检查¶
Slave按照repl-ping-slave-period的间隔（默认10秒），向Master发送ping。
如果主从间的链接中断后，再次连接的时候，2.8以前按照full sync再同期。2.8以后，因为有backlog的设定，backlog存在master的内存里，重新连接之前，如果redis没有重启，并且offset在backlog保存的范围内，可以实现从断开地方同期，不符合这个条件，还是full sync
用monitor命令，可以看到slave在发送ping
127.0.0.1:8380> slaveof localhost 8379 OK 127.0.0.1:8380> MONITOR OK 1551153843.193225 [0 127.0.0.1:8379] "PING"
用ping命令，可以看到slave在发送ping
root@leco:/usr/local/redis# redis-cli -p 8380 127.0.0.1:8380> ping PONG
注意
以上配置master主从是单个机器上启动的多少实例，多机主从，类似，配置文件稍微修改。