Windows 10 Canceled copy of large file to network at 2%, but entire file somehow copied?


New Member
I have a large 12gb .zip file that I downloaded locally. I started an upload to a network folder via a VPN connection off site. The connection is not fast so this would take 20-30min to fully upload. I canceled at 2% and decided to wait until another time to upload this file. The strange thing is, the entire file is shown on network after the cancel. I did a CRC check with 7zip and the size matches, but CRC # is different.

As a test, I copied the file back locally from network, and it appears to be copying a large 12gb file.

So question is, how could a 12gb file be on the network after canceling 15 seconds into a transfer? Can a network find a similar file elsewhere, and use that data instead of copying the same file?
It is possible that the partial transfer created some sort of placeholder on the network, which was then filled in with the remaining data once the transfer was resumed. This could explain why the entire file appears on the network, even though the transfer was canceled early.

Alternatively, it's possible that the network has some sort of caching or deduplication mechanism in place that allowed it to recognize that the file being transferred was already present on the network, and instead of copying the entire file, it simply transferred the remaining data to complete the file.

Regarding the CRC check, it's not uncommon for a partial transfer to result in a different CRC than the original file, especially if there were any errors or issues during the transfer. The fact that the size matches is a good sign though, as it suggests that the entire file was successfully transferred.

Overall, while it's not entirely clear how the transfer was able to complete despite being canceled early, it's likely due to some sort of optimization or caching mechanism on the network.
Get-FileHash -Algorithm SHA256 -Path <path/to/file> Running this powershell command against both copies will likely not match