You can set redis-shake to sync mode and then use it to migrate data from a self-managed Redis database to an ApsaraDB for Redis instance in real time. The migration does not cause service interruption.

Prerequisites

  • The version of the self-managed Redis database is Redis 2.8, 3.0, 3.2, 4.0, or 5.0.
    Note If you want to migrate data between different versions of Redis databases, for example, from Redis 2.8 to Redis 4.0, we recommend that you create a pay-as-you-go ApsaraDB for Redis instance to verify the compatibility. If no compatibility issue is found, you can change the billing method of the instance to subscription. For more information about how to change the billing method, see Change the billing method to subscription.
  • The destination ApsaraDB for Redis instance must meet the following requirements:
    • The destination ApsaraDB for Redis instance is of Community Edition (Redis 4.0 or 5.0) or Enhanced Edition (Redis 5.0).
    • The destination ApsaraDB for Redis instance use a standard or cluster architecture.
    Note If you have not created an instance, see Step 1: Create an ApsaraDB for Redis instance.

Redis-shake introduction

Redis-shake is an open source tool developed by Alibaba Cloud for Redis data transmission. You can use this flexible and efficient tool to parse (decode mode), restore (restore mode), back up (dump mode), and synchronize (sync or rump mode) data on ApsaraDB for Redis instances. When redis-shake works in sync mode, it supports both full data migration and incremental data migration. The detailed migration process is shown in the following figure.
Figure 1. Redis-shake data migration diagram
Redis-shake data migration diagram
Note You can also use the data synchronization feature of Data Transmission Service (DTS) to migrate data. DTS is applicable to more scenarios and supports more features. For more information, see Overview of data synchronization.

Precautions

  • If the data eviction policy (maxmemory-policy) of the destination database is not set to noeviction, data may become inconsistent between the source and destination databases. For more information about the data eviction policy, see How does ApsaraDB for Redis evict data by default?
  • After you run the info command to query the keys in the destination database, you may find that the destination database contains fewer keys than the source database. This is caused by the key expiration mechanism of Redis. This situation occurs if the source database contains keys that are not deleted upon expiration.
    Note The numbers of keys that do not have a validity period in the source and destination databases are the same.

Procedure

  1. Perform the following operations based on the location where redis-shake is installed:
    Note We recommend that you install redis-shake on the host where the self-managed database is deployed. This reduces network latency and prevents connection failures caused by the firewall settings of the self-managed database.
    Location where redis-shake is installed Operation
    ECS instances
    1. Make sure that the ECS instance and the ApsaraDB for Redis instance belong to the same VPC. They share the same VPC ID in the Basic Information section.
      Note
    2. Obtain the internal IP address of the ECS instance. For more information, see How do I query IP addresses of ECS instances.
    3. Add the internal IP address of the ECS instance to the whitelist of the ApsaraDB for Redis instance. For more information, see Configure whitelists.
    On-premises machine
    1. By default, an ApsaraDB for Redis instance provides only an internal endpoint. You must apply for a public endpoint when you want to connect to an ApsaraDB for Redis instance over the Internet. For more information, see Apply for a public endpoint.
    2. Run the curl ipinfo.io |grep ip command on the on-premises machine to obtain the public IP address. The returned result is shown in the following figure.View public IP address results
    3. Add the public IP address of the on-premises machine to the whitelist of the ApsaraDB for Redis instance. For more information, see Configure whitelists.
  2. Install redis-shake.
    1. Log on to the host where you want to install redis-shake. The host may be an ECS instance or an on-premises machine.
    2. Run the following command to download the redis-shake file.
      wget 'http://docs-aliyun.cn-hangzhou.oss.aliyun-inc.com/assets/attach/120287/cn_zh/1608173646665/redis-shake-v2.0.3.tar.gz'
      Note This example shows how to install redis-shake 2.0.3. You can also install redis-shake of other versions. For more information, see RedisShake.
    3. Run the following command to decompress the redis-shake file:
      tar xzf redis-shake-v2.0.3.tar.gz
  3. Migrate data from the host where redis-shake is installed.
    1. Run the following command to access the directory of the decompressed redis-shake file and modify the configuration file:
      cd redis-shake-v2.0.3/ && vim redis-shake.conf
      Note After the command is run, the system will open an editing interface. Enter a to enter the editing mode.
      Table 1. Parameters
      Parameter Required Description Example
      source.type Yes Select a value based on the architecture of the source database (self-managed database). Valid values:
      • standalone: master-replica architecture.
      • cluster: cluster architecture.
      		standalone
      source.address Yes The connection address and port number of the source database. Separate the connection address and port number with a colon (:).
      Note
      • If the source database and redis-shake are deployed on the same host, enter 127.0.0.1:6379.
      • If the source database is a cluster instance, you must add the master@ prefix to the connection address, for example, master@127.0.0.1:6379.
      		127.0.0.1:6379
      source.password_raw Yes The password of the source database. If no password is set for the source database, you do not need to specify a password. Rp829dlwa
      target.type Yes Select a value based on the architecture of the destination ApsaraDB for Redis instance. Valid values: standalone
      target.address Yes The connection address and port number of the destination ApsaraDB for Redis instance. Separate the connection address and port number with a colon (:). For more information about how to obtain the connection address and port number of the ApsaraDB for Redis instance, see .
      • The ECS instance is connected through a virtual private cloud (VPC): You must obtain the internal endpoint of the ApsaraDB for Redis instance.
      • If you connect an on-premises machine to the ApsaraDB for Redis instance over the Internet, you must obtain the public IP address of the ApsaraDB for Redis instance.
      Note If the destination instance uses the cluster architecture, you must connect to the instance deployed in a VPC by using a private endpoint. You must add the prefix master@ to the connection address, for example, master@r-bp1mfnrflszg75w****.redis.rds.aliyuncs.com:6379. For more information about how to request a private endpoint, see Enable the direct connection mode.
      		r-bp1wcw2rlw76acc5k****.redis.rds.aliyuncs.com:6379
      target.password_raw Yes The account with read and write permissions and the password of the destination ApsaraDB for Redis instance. Separate the account and password with a colon (:). For more information about how to create an account, see Create and manage database accounts. testaccount:Rp829dlwa
      target.db No Migrates data from all databases in the source database to the specified databases of the destination database. Valid values: 0 to 15.
      Note The default value -1 indicates that the feature is disabled.
      		-1
      key_exists No The data writing policy that is applied when the keys in the source database are the same as those in the destination database. Valid values:
      • rewrite: overwrites the existing keys in the destination database that are the same as those in the source database.
      • none: This is the default value. Redis-shake stops running and a message that indicates conflicting keys appears.
      • ignore: skips the current key, retains the data in the destination database, and continues to migrate data.
      		rewrite
      filter.db.whitelist No The names of the databases to be migrated. Separate multiple database names with semicolons (;). By default, this parameter is left empty. This indicates that all databases are migrated. 0;1
      filter.db.blacklist No The names of databases that you do not want to migrate. This parameter is equivalent to a blacklist. Separate multiple database names with semicolons (;). By default, this parameter is left empty. This indicates that no database is added to the blacklist. 1;2
      parallel No The number of concurrent threads for redis-shake to perform the migration tasks. You can increase this value to improve synchronization performance.
      Note The default value is 32. The minimum value is 1. The maximum value depends on the performance of the server where redis-shake is deployed.
      		32
      Note You do not need to configure other parameters unless otherwise required. For more information, see the comments on each parameter in the redis-shake.conf file.
    2. Press the Esc key to exit the editing mode and enter :wq to save and close the file.
    3. Run the following command to start redis-shake and migrate data:
      ./redis-shake.linux -type=sync -conf=redis-shake.conf
      Redis-shake prints the operational log on the screen.
      Note For more information about the causes of related errors and how to fix these errors, see FAQ.
  4. Optional:Stop the data migration task as required.
    Note If you need to run redis-shake for a long time to migrate data in real time, skip this step.
    1. Check the log data and wait until the migration task enters the incremental data migration state.
      Task stage Logs
      Full data migration 
      2020/12/16 21:02:36 [INFO] DbSyncer[0] total = 4.00MB -       2.18MB [ 54%]  entry=52199
2020/12/16 21:02:36 [INFO] DbSyncer[0] total = 4.00MB -       4.00MB [100%]  entry=97531
2020/12/16 21:02:36 [INFO] DbSyncer[0] sync rdb done
      Note When sync rdb done appears in the log data, full synchronization is completed and incremental synchronization starts.
      Incremental data migration 
      2020/12/16 21:03:07 [INFO] DbSyncer[0] sync:  +forwardCommands=5      +filterCommands=0      +writeBytes=5095
2020/12/16 21:03:08 [INFO] DbSyncer[0] sync:  +forwardCommands=7      +filterCommands=0      +writeBytes=7133
2020/12/16 21:03:09 [INFO] DbSyncer[0] sync:  +forwardCommands=0      +filterCommands=0      +writeBytes=0
2020/12/16 21:03:10 [INFO] DbSyncer[0] sync:  +forwardCommands=645    +filterCommands=0      +writeBytes=657255
2020/12/16 21:03:11 [INFO] DbSyncer[0] sync:  +forwardCommands=28     +filterCommands=0      +writeBytes=28532
2020/12/16 21:03:12 [INFO] DbSyncer[0] sync:  +forwardCommands=0      +filterCommands=0      +writeBytes=0
      The log contains the following parameters:
      • forwardCommands: the number of commands that are sent from the source database.
      • filterCommands: the number of commands that are filtered out. For example, you can set the configuration file of redis-shake to filter out specific databases.
      • writeBytes: the number of bytes that are sent from the source database.
    2. Stop writing data to the source database and wait until the value of the writeBytes parameter in the returned log remains 0 for multiple times in succession, and then press Ctrl+C to stop the running of redis-shake.
      Figure 2. Stop running example
      Stop running example
      Note The preceding figure indicates that the data in the source databases and destination databases is consistent. You can switch workloads from the self-managed Redis database to the ApsaraDB for Redis instance.