AWS S3 sync command from one bucket to another

Question

I want to use the AWS S3 sync command to sync a large bucket with another bucket. I found this answer that say that the files from the bucket synced over the AWS backbone and are not copied to the local machine but I can't find a reference anywhere in the documentation. Does anyone has a proof for this behavior? any formal documentation that explains how it works?

I tried to find something in the documentation but nothing there.

Answer 1

To learn more about the sync command, check CLI docs . You can directly refer to the section named -

Sync from S3 bucket to another S3 bucket

The following sync command syncs objects to a specified bucket and prefix from objects in another specified bucket and prefix by copying s3 objects. An s3 object will require copying if one of the following conditions is true:

• The s3 object does not exist in the specified bucket and prefix destination.
• The sizes of the two s3 objects differ.
• The last modified time of the source is newer than the last modified time of the destination.

Use the S3 replication capability if you only want to replicate the data that moves from bucket1 to bucket2.