Help Center/ Distributed Cache Service/ User Guide (Kuala Lumpur Region)/ Troubleshooting/ Troubleshooting Data Migration Failures
Updated on 2024-07-29 GMT+08:00
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Troubleshooting Data Migration Failures

When you use the console to migrate data, the migration may fail if you select an inappropriate migration scheme, the SYNC and PSYNC commands are not allowed on the source Redis instance, or the network between the source and target Redis instances is disconnected.

This section describes how to troubleshoot data migration failures on the DCS console.

Procedure

  1. Check the migration logs.

    • If the following error information is displayed, the underlying resources are insufficient to support the migration task. In this case, contact technical support. 
      create migration ecs failed, flavor
    • If the following error information is displayed, the SYNC and PSYNC commands are disabled on the source Redis instance. In this case, contact technical support to enable the commands. 
      source redis unsupported command: psync

  2. Check whether you used the appropriate migration scheme. If you migrate data between DCS Redis instances, the source instance cannot be a higher version than the target instance.
  3. Check whether the SYNC and PSYNC commands are enabled on the source Redis instance and whether the underlying resources of the migration task are connected to the source and target Redis instances.

    This operation is required only for online migration.

    For online migration, the source and target Redis instances must be connected, and the SYNC and PSYNC commands must be enabled on the source Redis instance. Otherwise, the migration will fail.

    • Check the network.

      Check whether the source Redis instance, the target Redis instance, and the VMs used for the migration task are in the same VPC. If they are in different VPCs, create a VPC peering connection. For details, see "VPC Peering Connection" in the Virtual Private Cloud User Guide.

      If they are in the same VPC, check the security group rules (for DCS Redis 3.0 instances) or whitelists (for DCS Redis 4.0/5.0/6.0 instances) to ensure that the IP addresses and ports of the Redis instances are accessible.

      The source and target Redis instances must be accessible to the underlying VMs used for the migration task. For details about how to configure a security group or whitelist, see Security Group Configurations and Managing IP Address Whitelist.

      If the source and target Redis instances are on different clouds, create a Direct Connect connection.

    • Check the commands.
      By default, the SYNC and PSYNC commands are disabled by cloud vendors. To enable the commands, contact the O&M personnel of the cloud vendors.
      • Migration within DCS:
        • By default, the SYNC and PSYNC commands can be used when self-hosted Redis is migrated to DCS.
        • During online migration between DCS instances in the same region under the same account, the SYNC and PSYNC commands are automatically enabled.
        • During online migration between DCS instances in different regions or under different accounts within a region, the SYNC and PSYNC commands are not automatically enabled, and online migration on the console cannot be used. You can migrate data using backup files instead.
      • Migration from other cloud vendors to DCS:
        • Generally, cloud vendors disable the SYNC and PSYNC commands. If you want to use online migration, contact the O&M personnel of the source cloud vendor to enable the commands. For offline migration, you can import backup files.
        • If incremental migration is not required, you can perform full migration by referring to Online Full Migration of Redis from Another Cloud with redis-shake. This method does not depend on SYNC and PSYNC.

  4. Check the source Redis instance for big keys.

    If the source Redis instances has big keys, split them into small keys before migration.

  5. Check the specifications of the target Redis instance and whether other tasks are being performed on the instance.

    If the memory of the target Redis instance is smaller than the size of the data to be migrated, the memory will be used up during the migration and the migration will fail.

    If a master/standby switchover is being performed on the target Redis instance, contact technical support to stop the master/standby switchover task and start it only after the data migration is completed.

  6. Check whether the migration task is performed correctly.

    Check whether the IP address and the instance password are correct.

  7. Check the whitelist.
  8. If the fault persists, contact technical support.
Parent topic: Troubleshooting