Hello @asn_india,
> Would you be able to share some statistics around the usage of content transfer tool? interested in assets migration from non-cloud to cloud(6.4 to cloud)
Adobe has introduced a new tool called the Cloud Acceleration Manager which will be able to help answer these questions, in addition to helping with other aspects of the transition journey starting from planning to going live on Cloud Service.
> What is a comfortable set size?
This depends on the configuration of AEM's data store: if using a File Data Store, the current limit is 10 TB (Prerequisites for Content Transfer Tool doc link). If using an Amazon S3 or Azure Blob Storage data store, we can transfer binary data much faster in a "pre-copy" step, and this limit does not apply. The CTT documentation covers this approach in Handling Large Content Repositories.
> How much time did it take for extraction phase on source Author?
The Cloud Acceleration Manager provides a "Content Transfer Calculator" which will provide an estimate on what you can expect for a time range, with or without a binary "pre-copy" (as described above, for Amazon S3 or Azure Blob Storage data stores):
> how much time did it take for ingestion phase for that set on target ccloud author?
This time will vary based on the size of the segment and data stores on the source AEM instance. Once the initial ingestion is complete, additional "delta" or "top-up" ingestions can be run which will take less time than the initial transfer, relative to the amount of content added. This can help reduce the total "content freeze" time necessary prior to cutting over to the AEMaaCS environment. Please refer to the Using Content Transfer Tool doc for additional details.