前言
最近线上一台自建redis服务的服务器频繁报警，内存使用率有点高，这是一台配置比较简陋（2C8G）的机子了，近期也打算准备抛弃它了。抛弃之前需对原先的数据进行迁移，全量数据，增量数据都需要考虑，确保数据不丢失，在网上查了下发现了阿里自研的RedisShake工具，据说很妙，那就先试试吧。
实战
正式操作前先在测试环境实践一把看看效果如何，先说明下环境
源库：192.168.28.142
目标库：192.168.147.128
步骤一：
使用wget命令下载至本地
wget https://github.com/alibaba/RedisShake/releases/download/release-v2.0.2-20200506/redis-shake-v2.0.2.tar.gz
步骤二：
解压，进入相应目录看看有哪些东东
[root@dev ~]# cd /opt/redis-shake/
[root@dev redis-shake]# ls
redis-shake-v2.0.2.tar.gz
[root@dev redis-shake]# tar -zxvf redis-shake-v2.0.2.tar.gz
redis-shake-v2.0.2/
redis-shake-v2.0.2/redis-shake.darwin
redis-shake-v2.0.2/redis-shake.windows
redis-shake-v2.0.2/redis-shake.conf
redis-shake-v2.0.2/ChangeLog
redis-shake-v2.0.2/stop.sh
redis-shake-v2.0.2/start.sh
redis-shake-v2.0.2/hypervisor
redis-shake-v2.0.2/redis-shake.linux
[root@dev redis-shake]# ls
redis-shake-v2.0.2 redis-shake-v2.0.2.tar.gz
[root@dev redis-shake]# cd redis-shake-v2.0.2
[root@dev redis-shake-v2.0.2]# ls
ChangeLog hypervisor redis-shake.conf redis-shake.darwin redis-shake.linux redis-shake.windows start.sh stop.sh
步骤三：
更改配置文件redis-shake.conf
日志输出
# log file，日志文件，不配置将打印到stdout (e.g. /var/log/redis-shake.log )
log.file =/opt/redis-shake/redis-shake.log
源端连接配置
# ip:port
# the source address can be the following:
# 1. single db address. for "standalone" type.
# 2. ${sentinel_master_name}:${master or slave}@sentinel single/cluster address, e.g., mymaster:master@127.0.0.1:26379;127.0.0.1:26380, or @127.0.0.1:26379;127.0.0.1:26380. for "sentinel" type.
# 3. cluster that has several db nodes split by semicolon(;). for "cluster" type. e.g., 10.1.1.1:20331;10.1.1.2:20441.
# 4. proxy address(used in "rump" mode only). for "proxy" type.
# 源redis地址。对于sentinel或者开源cluster模式，输入格式为"master名字:拉取角色为master或者slave@sentinel的地址"，别的cluster
# 架构，比如codis, twemproxy, aliyun proxy等需要配置所有master或者slave的db地址。
source.address = 192.168.28.142:6379
# password of db/proxy. even if type is sentinel.
source.password_raw = xxxxxxx
目标端设置
# ip:port
# the target address can be the following:
# 1. single db address. for "standalone" type.
# 2. ${sentinel_master_name}:${master or slave}@sentinel single/cluster address, e.g., mymaster:master@127.0.0.1:26379;127.0.0.1:26380, or @127.0.0.1:26379;127.0.0.1:26380. for "sentinel" type.
# 3. cluster that has several db nodes split by semicolon(;). for "cluster" type.
# 4. proxy address. for "proxy" type.
target.address = 192.168.147.128:6379
# password of db/proxy. even if type is sentinel.
target.password_raw = xxxxxx
# auth type, don't modify it
target.auth_type = auth
# all the data will be written into this db. < 0 means disable.
target.db = -1
步骤四
./start.sh redis-shake.conf sync
查看日志文件
2020/05/15 09:00:29 [INFO] DbSyncer[0] starts syncing data from 192.168.28.142:6379 to [192.168.147.128:6379] with http[9321], enableResumeFromBreakPoint[false], slot boundary[-1, -1]
2020/05/15 09:00:29 [INFO] DbSyncer[0] psync connect '192.168.28.142:6379' with auth type[auth] OK!
2020/05/15 09:00:29 [INFO] DbSyncer[0] psync send listening port[9320] OK!
2020/05/15 09:00:29 [INFO] DbSyncer[0] try to send 'psync' command: run-id[?], offset[-1]
2020/05/15 09:00:29 [INFO] Event:FullSyncStart Id:redis-shake
2020/05/15 09:00:29 [INFO] DbSyncer[0] psync runid = 0a08aa75b91f8724014e056cd2c3068eebf81ec4, offset = 126, fullsync
2020/05/15 09:00:30 [INFO] DbSyncer[0] +
2020/05/15 09:00:30 [INFO] DbSyncer[0] rdb file size = 45173748
2020/05/15 09:00:30 [INFO] Aux information key:redis-ver value:4.0.10
2020/05/15 09:00:30 [INFO] Aux information key:redis-bits value:64
2020/05/15 09:00:30 [INFO] Aux information key:ctime value:1589521609
2020/05/15 09:00:30 [INFO] Aux information key:used-mem value:66304824
2020/05/15 09:00:30 [INFO] Aux information key:repl-stream-db value:0
2020/05/15 09:00:30 [INFO] Aux information key:repl-id value:0a08aa75b91f8724014e056cd2c3068eebf81ec4
2020/05/15 09:00:30 [INFO] Aux information key:repl-offset value:126
2020/05/15 09:00:30 [INFO] Aux information key:aof-preamble value:0
2020/05/15 09:00:30 [INFO] db_size:8 expire_size:0
2020/05/15 09:00:31 [INFO] DbSyncer[0] total = 43.08MB - 10.87MB [ 25%] entry=0 filter=4
2020/05/15 09:00:32 [INFO] DbSyncer[0] total = 43.08MB - 21.78MB [ 50%] entry=0 filter=5
2020/05/15 09:00:33 [INFO] DbSyncer[0] total = 43.08MB - 32.64MB [ 75%] entry=0 filter=5
2020/05/15 09:00:34 [INFO] DbSyncer[0] total = 43.08MB - 42.92MB [ 99%] entry=0 filter=6
2020/05/15 09:00:34 [INFO] db_size:1 expire_size:0
2020/05/15 09:00:34 [INFO] db_size:48 expire_size:12
2020/05/15 09:00:34 [INFO] db_size:533 expire_size:468
2020/05/15 09:00:34 [INFO] DbSyncer[0] total
查看下数据同步情况，如下图，发现所有的库都同步过来了，非常nice。
但如果只想同步某个库又该怎么操作呢？
马上查阅了配置文件及官方文档，稍作调整就可以，具体如下
| 配置项 | 说明 |
|---|---|
| target.db | 设置待迁移的数据在目的Redis中的逻辑数据库名。例如，要将所有数据迁移到目的Redis中的DB10，则需将此参数的值设置为10。当该值设置为-1时，逻辑数据库名在源Redis和目的Redis中的名称相同，即源Redis中的DB0将被迁移至目的Redis中的DB0，DB1将被迁移至DB1，以此类推。 |
| filter.db.whitelist | 指定的db被通过，比如0;5;10将会使db0, db5, db10通过, 其他的被过滤 |
那比如我这边只想把源端的10库同步至目标端的10库只需对配置文件进行如下改动
target.db = 10
filter.db.whitelist =10
重新执行步骤四命令，执行后效果如下，大功告成。
另外还有一个配置项特意说明下
| 配置项 | 说明 |
|---|---|
| key_exists | 当源目的有重复key，是否进行覆写。rewrite表示源端覆盖目的端。none表示一旦发生进程直接退出。ignore表示保留目的端key，忽略源端的同步key。该值在rump模式下没有用。 |
当前仅仅是单个节点到单个节点的同步，如涉及到集群等其他一些场景下，请参考官方文档说明，自行测试。
