Problem uploading large files to AWS S3

Because of the way S3 is designed, it is impossible to upload any file to an S3 bucket until its complete size is known. Thus, when you copy a file into an S3 volume in ExpanDrive, no writing actually occurs over the network until the file is actually closed (the first moment at which ExpanDrive knows its full size). For very large files, this means that closing the file costs basically all the time it takes to really upload the file to S3.

This is an unfortunate but currently unavoidable architectural limitation of S3. You might want to consider using a file-transfer application instead of ExpanDrive for bulk uploads of large files to S3. When the Finder copies a file to an ExpanDrive S3 volume, it writes the data a little at a time, whereas a file-transfer program can see the whole file in advance, so no delay is needed. Once your large files are uploaded, ExpanDrive can access them just fine, but uploading them will always incur the pause, at present. We are hoping the AWS developers will implement a somewhat more flexible writing behaviour in the future.

Even so, the copy should not freeze the Finder. Windows for volumes other than the S3 drive should operate normally, even during a large copy. If you're having a different experience, please drop us a note at <support@expandrive.com> so we can help you troubleshoot.