How do I move a redis database from one server to another?

问题

I currently have a live redis server running on a cloud instance and I want to migrate this redis server to a new cloud instance and use that instance as my new redis server. If it were MySQL, I would export the DB from the old server and import it into the new server. How should I do this with redis?

P.S.: I'm not looking to set-up replication. I want to completely migrate the redis server to a new instance.

回答1:

Save a snapshot of the database into a dump.rdb by either running BGSAVE or SAVE from the command line. This will create a file named dump.rdb in the same folder as your redis server. See a list of all server commands.

Copy this dump.rdb to the other redis server you want to migrate to. When redis starts up, it looks for this file to initialize the database from.

回答2:

First, create a dump on server A.

A$ redis-cli
127.0.0.1:6379> CONFIG GET dir
1) "dir"
2) "/var/lib/redis/"
127.0.0.1:6379> SAVE
OK

This ensures dump.rdb is completely up-to-date, and shows us where it is stored (/var/lib/redis/dump.rdb in this case). dump.rdb is also periodically written to disk automatically.

Next, copy it to server B:

A$ scp /var/lib/redis/dump.rdb myuser@B:/tmp/dump.rdb

Stop the Redis server on B, copy dump.rdb (ensuring permissions are the same as before), then start.

B$ sudo service redis-server stop
B$ sudo cp /tmp/dump.rdb /var/lib/redis/dump.rdb
B$ sudo chown redis: /var/lib/redis/dump.rdb
B$ sudo service redis-server start

The version of Redis on B must be greater or equal than that of A, or you may hit compatibility issues.

回答3:

If you have the connectivity between servers it is better to set up replication (which is trivial, unlike with SQL) with the new instance as a slave node - then you can switch the new node to master with a single command and do the move with zero downtime.

回答4:

believe or not, I just made article for it:

http://redis4you.com/articles.php?id=005&name=Seamless+migration+from+one+Redis+server+to+another

But how do I know when the data transfer is complete between the master and the slave? You can use INFO command.

回答5:

It is also possible to migrate data using the SLAVEOF command:

SLAVEOF old_instance_name old_instance_port

Check that you have receive the keys with KEYS *. You could test the new instance by any other way too, and when you are done just turn replication of:

SLAVEOF NO ONE

回答6:

Nowadays you can also use MIGRATE, available since 2.6.

I had to use this since I only wanted to move the data in one database and not all of them. The two Redis instances live on two different machines.

If you can't connect directly to Redis-2 from Redis-1, use ssh port binding:

 ssh user@redis-2.foo.com -L 1234:127.0.0.1:6379

A small script to loop all the keys using KEYS and MIGRATE each key. This is Perl, but hopefully you get the idea:

 foreach ( $redis_from->keys('*') ) {

    $redis_from->migrate(
        $destination{host},    # localhost in my example
        $destination{port},    # 1234
        $_,                    # The key
        $destination{db},
        $destination{timeout} 
    );
 }

See http://redis.io/commands/migrate for more info.

回答7:

To check where the dump.rdb has to be placed when importing redis data,

start client

$redis-cli

and

then

redis 127.0.0.1:6379> CONFIG GET *
 1) "dir"
 2) "/Users/Admin"

Here /Users/Admin is the location of dump.rdb that is read from server and therefore this is the file that has to be replaced.

回答8:

you can also use rdd

it can dump & restore a running redis server and allow filter/match/rename dumps keys

回答9:

I also want to do the same thing: migrate a db from a standalone redis instance to a another redis instances(redis sentinel).

Because the data is not critical(session data), i will give https://github.com/yaauie/redis-copy a try.

回答10:

The simple way I found to export / Backup Redis data (create dump file ) is to start up a server via command line with slaveof flag and create live replica as follow (assuming the source Redis is 1.2.3.4 on port 6379):

/usr/bin/redis-server --port 6399 --dbfilename backup_of_master.rdb --slaveof 1.2.3.4 6379

回答11:

I just published a command line interface utility to npm and github that allows you to copy keys that match a given pattern (even *) from one Redis database to another.

You can find the utility here:

https://www.npmjs.com/package/redis-utils-cli

回答12:

Key elements of a zero-downtime migration is:

replication (http://redis.io/commands/SLAVEOF)
possibility to write into a slave during application switching (CONFIG SET slave-read-only no)

In short:

setup a target redis (empty) as slave of a source redis (with your data)
wait for replication finish
permit writes to a target redis (which is currently slave)
switch your apps to a target redis
wait for finish datastream from master to slave
turn a target redis from master to slave

Additionally redis have options which allows to disable a source redis to accept writes right after detaching a target:

min-slaves-to-write
min-slaves-max-lag

This topic covered by

http://redis.io/topics/admin#upgrading-or-restarting-a-redis-instance-without-downtime

Very good explanation from RedisLabs team https://redislabs.com/blog/real-time-synchronization-tool-for-redis-migration

And even their interactive tool for migrate: https://github.com/RedisLabs/redis-migrate

回答13:

redis-dump finally worked for me. Its documentation provides an example how to dump a Redis database and insert the data into another one.

来源：https://stackoverflow.com/questions/6004915/how-do-i-move-a-redis-database-from-one-server-to-another

标签

database

Redis

data-migration

database-migration