Data Online Migration enforces limits on the number of resources, concurrency, bandwidth, and QPS for each region.
Resource limits
The following table lists the maximum number of resources you can create in each region.
Resource | Maximum per region |
Migration task | 500 |
Data address | 1,000 |
Agent | 100 |
Channel | 100 |
Concurrency
Each region limits the number of concurrent migration tasks. Tasks will fail to start if this limit is reached.
Region | Maximum concurrency |
China (Hangzhou) | 10 |
China (Shanghai) | 10 |
China (Beijing) | 10 |
China (Ulanqab) | 10 |
China (Shenzhen) | 10 |
China (Chengdu) | 10 |
China (Hong Kong) | 10 |
Japan (Tokyo) | 5 |
Singapore | 5 |
Germany (Frankfurt) | 5 |
US (Virginia) | 5 |
Tasks in the following states count toward the concurrency limit: Starting, Preparing, Migrating, Stopping, and Deleting.
If the concurrency limit is reached, scheduled tasks may not start on schedule.
Task bandwidth and QPS
Each migration task is subject to bandwidth and QPS limits. The following table lists the limits for each region.
Region | Maximum bandwidth per task | Maximum QPS per task |
China (Hangzhou) | 2 Gbps | 2,000 |
China (Shanghai) | 2 Gbps | 2,000 |
China (Beijing) | 2 Gbps | 2,000 |
China (Ulanqab) | 2 Gbps | 2,000 |
China (Shenzhen) | 2 Gbps | 2,000 |
China (Chengdu) | 2 Gbps | 2,000 |
China (Hong Kong) | 2 Gbps | 2,000 |
Japan (Tokyo) | 1 Gbps | 2,000 |
Singapore | 1 Gbps | 2,000 |
Germany (Frankfurt) | 1 Gbps | 2,000 |
US (Virginia) | 1 Gbps | 2,000 |
If the destination is a LocalFs data address, the maximum QPS per task is 200, regardless of the region.
The bandwidth and QPS values in the preceding table are theoretical maximums. Actual throughput depends on the read and write capabilities of the source and destination systems.
Data Online Migration consumes resources at both the source and destination, which can affect your running applications. For critical workloads, we recommend that you assess the potential impact and either configure a rate limit for the migration task or run the task during off-peak hours.
To obtain higher public bandwidth, you can purchase your own ECS instances with public bandwidth and migrate the data by using an agent. Ensure that the agent's network type is set to VPC. For more information, see Migrate data using an agent.
Channel bandwidth and QPS
For agent-based migrations, channel bandwidth and QPS are limited at the UID level. QPS measures requests per second, and migrating a single file requires multiple requests. To request a higher channel quota, submit a ticket.
Region | Bandwidth per UID | QPS per UID |
Any region | 20 Gbps | 10,000 |
For example, if you create three channels in the China (Hangzhou) region and associate them with multiple tasks running concurrently, the total traffic and QPS from all tasks cannot exceed the per-UID limits in the preceding table.
Other limitations
Limitation | Description |
Migration result verification | After a migration task is complete, you must verify the data consistency between the source and destination. For more information, see the Data Transport Service Agreement. Warning: You must verify that the migrated data at the destination is correct before you delete the source data. You are solely responsible for any data loss that occurs if you delete the source data without verification. |
Archived data | Before you migrate archived data, you must first restore it. When restoring the data, keep the following in mind:
Note: Data Online Migration does not perform restore operations on source data. If the source contains files that are not restored or are still being restored, the migration of these files will fail. |
Cross-border migration | Cross-border migration over the public internet may fail due to network instability. |