Migrate data between ApsaraDB for Redis instances by using Redis-shake - Data Migration And Synchronization| Alibaba Cloud Documentation Center

When Redis-shake works in sync mode, it supports both full data migration and incremental data migration. This allows you to migrate data between ApsaraDB for Redis instances that belong to the same or different Alibaba Cloud accounts.

Prerequisites

The source and destination ApsaraDB for Redis instances must meet the following conditions:


ApsaraDB for Redis	Condition
Source ApsaraDB for Redis instance	The instance is of Community Edition (Redis 4.0 or 5.0). Note If the instance is of Enhanced Edition, you can use the data synchronization feature of Data Transmission Service (DTS) to migrate data. For more information, see Overview of data synchronization. The instance uses the standard architecture or the cluster architecture.
Destination ApsaraDB for Redis instance	The instance is of Community Edition (Redis 4.0 or 5.0) or Enhanced Edition (Redis 5.0). The instance uses the standard architecture or the cluster architecture. Note If you have not created a destination ApsaraDB for Redis instance, see Step 1: Create an ApsaraDB for Redis instance. If you want to migrate data between different versions of Redis databases, for example, from Redis 4.0 to Redis 5.0, 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 convert the billing method of the instance to subscription. For more information about how to convert the billing method, see Change the billing method to subscription.

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

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.

Scenarios

Migrate data across Alibaba Cloud accounts
Migrate data between instances that belong to the same Alibaba Cloud account

Procedure

Perform the following operations based on the location where redis-shake is installed:

Note

The ApsaraDB for Redis instances mentioned in the following table refer to both the source and destination ApsaraDB for Redis instances. Perform the following operations on both the source and destination ApsaraDB for Redis instances.
We recommend that you install redis-shake on Elastic Compute Service (ECS) instances. You can connect to the source and destination ApsaraDB for Redis instances through a virtual private cloud (VPC) to achieve lower network latency and higher security.
To perform migration tasks across Alibaba Cloud accounts, we recommend that you deploy redis-shake on the ECS instance that belongs to your Alibaba Cloud account. Then, you can connect to the source ApsaraDB for Redis instance through a VPC. You can connect to the destination ApsaraDB for Redis instance over the Internet.


Location where Redis-shake is installed	Operation
ECS instance (recommended)	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 If they are deployed in different VPCs, you can change the VPC to which the ECS instance belongs. For more information, see Change the VPC of an ECS instance. The network types are distinct. For example, the ECS instance belongs to a classic network and the ApsaraDB for Redis instance belongs to a VPC. For more information about how to connect to an ApsaraDB for Redis instance from an ECS instance when they are deployed in different types of networks, see Connect an ECS instance to an ApsaraDB for Redis instance in different types of networks. Obtain the internal IP address of the ECS instance. For more information, see How do I query IP addresses of ECS instances. Add the internal IP address of the ECS instance to the whitelist of the ApsaraDB for Redis instance. For more information, see Configure an IP whitelist.
On-premises machine	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. 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. Add the public IP address of the on-premises machine to the whitelist of the ApsaraDB for Redis instance. For more information, see Configure an IP whitelist.

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
```

Migrate data from the host where redis-shake is installed.

Run the following command to access the directory of the decompressed backup file and modify the configuration file:

cd redis-shake-v2.0.3/ && vim redis-shake.conf

Note After the command is run, the system opens 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 ApsaraDB for Redis instance. Valid values: standalone: standard architecture. cluster: cluster architecture.	standalone
source.address	Yes	The connection address and port number of the source 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 View endpoints. 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 endpoint of the ApsaraDB for Redis instance. Note If the source instance uses the cluster architecture, you must connect to the instance deployed in a VPC by using a private endpoint. You must add the `master@` prefix 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 connect mode.	r-bp1mfnrflszg75w****.redis.rds.aliyuncs.com:6379
source.password_raw	Yes	The account with Copy permissions and the password of the source 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. Note You are not allowed to create accounts with Copy permissions for instances that use the cluster architecture. To enable this feature, submit a ticket.	testaccount:Rp829dlwa
target.type	Yes	Select a value based on the architecture of the destination ApsaraDB for Redis instance. Valid values: standalone: standard architecture. cluster: cluster architecture.	cluster
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 View endpoints. 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 endpoint 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 `master@` prefix to the connection endpoint, for example, `master@r-bp1mfnrflszg75w****.redis.rds.aliyuncs.com:6379`. For more information about how to request a private endpoint, see Enable the direct connect mode.	master@r-bp1mfnrflszg75w****.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	Specifies whether to migrate data from all databases in the source ApsaraDB for Redis instance to the specified databases in the destination ApsaraDB for Redis instance. Valid values: -1 (default): disables this feature. 0 to 255: enables this feature. The value specifies the database of the destination of the destination ApsaraDB for Redis instance. For example, a value of 0 indicates that the aggregated data of all databases in the source ApsaraDB for Redis instance is migrated to database 0 in the destination ApsaraDB for Redis instance. Note If the source ApsaraDB for Redis instance uses the standard architecture and the destination ApsaraDB for Redis instance is of the cluster architecture, only database 0 is synchronized in this scenario. Data from other databases is not migrated. Set this parameter to 0 to migrate all the databases from the source ApsaraDB for Redis instance to database 0 in the destination ApsaraDB for Redis instance.	-1
key_exists	No	The 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 appears and indicates conflicting keys. 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, which indicates that all databases are to be migrated.	0;1
filter.db.blacklist	No	The names of databases that do not need to be migrated. This is 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.

Press the Esc key to exit the editing mode and enter :wq to save and close the file.
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.

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.

Check the logs and wait until the migration task enters the incremental data migration state.

Task stage Logs

Full data migration

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 logs, 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 following parameters in logs are described. `forwardCommands`: the number of commands that are sent from the source ApsaraDB for Redis instance. `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 ApsaraDB for Redis instance.

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 logs, 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 following parameters in logs are described.

forwardCommands: the number of commands that are sent from the source ApsaraDB for Redis instance.
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 ApsaraDB for Redis instance.

Stop writing data to the source database, wait until the value of the writeBytes parameter in the log returns a value of 0 multiple times, and then press Ctrl+C to stop redis-shake.

Figure 2. Stop running example

Note In this case, the data in the source ApsaraDB for Redis instance and the destination ApsaraDB for Redis instance is consistent. You can switch the workloads from the source ApsaraDB for Redis instance to the destination ApsaraDB for Redis instance.