Live Migration in mongodb atlas b/w sharded clusters

Hi Team,

I am performing live migration from source cluster to destination cluster. Before cutover, Is it possible to connect to the destination cluster and modify few collections

Hey @saiprasanthkumar_P,

To clarify, do you intend to modify the collection in the destination cluster before the cutover? What specific modification operations are you planning to perform on the destination cluster? Could you share your use case and may I ask why changes couldn’t be done before the migration process begins?

Also, could you please confirm if the migration is from a self-managed environment to MongoDB Atlas, or where the source cluster is currently hosted and it’s configuration?

Meanwhile, you can refer to the Avoid Workloads on the Destination Cluster and Migrate or Import Data documentation to gain a deeper understanding of the migration process and its limitations.

Best regards,
Kushagra

Hi @Kushagra_Kesav ,

Yes , I wanted to modify the collection in the destination cluster before the cutover. I wanted to add few new collection , connect mongodb with my application and do some testing in the application environment.

After the migration the entire cluster will be replaced with source cluster db . So if I do any changes before the migration (like adding new collection to the db) it may not work out

Migration is done between source sharded atlas cluster and destination sharded atlas cluster.

Regards,
Saiprasanth kumar

Hey @saiprasanthkumar_P,

Thanks for the clarification.

You can perform writes to the destination during migration, but it’s even safer to do so after the cutover (once the migration is complete). It is not recommended to do this during the migration process because if you add a conflicting namespace in the destination, which the source is trying to copy over, the migration process can run into an error.

Additionally, ensure that your source and destination clusters are running on MongoDB 6.0.8 or later as well as they are both sharded clusters with the same number of shards to utilize the Live Migration Feature. It is also recommended to thoroughly review each step of the Live Migration documentation to understand the restrictions, prerequisites, and pre-migration considerations.

I hope it helps. In case of any further questions, feel free to reach out.

Best regards,
Kushagra

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Hi @Kushagra_Kesav ,

Once the migration process gets started, I am not able to browse the collection through mongo atlas or any external client tool.

Browse collection button turns disabled during migration.

Since you pointed out that we can perform writes to the destination during migration , Do we have any way to perform those writes

Hey @saiprasanthkumar_P,

Could you access the database, or does the problem still persist? I’ll suggest raising a support ticket with the agreed SLA is the best option. Details on support plans are available through the UI as part of the procedure to change your support plan or by contacting MongoDB

Best regards,
Kushagra