Does IIS FTP Lock Files when Client is Downloading?

Question

I've been sent here from the nomral Stack Overflow with my issue

• TL;DR : Does IIS FTP service lock files while said files are being accessed, specifically downloaded, by an FTP client?

So I've got an FTP server up and running. My Server application, SSIS, copies files over into this folder and then the client will try and download them.

I've now hit an issue where my application can't overwrite the file as it already exists. I'm copying the file using a File System Task with Overwrite enabled. This usually works most of the time but I'm now faced with the above issue where it is saying it can't copy the file as it already exists.

I've ruled out that the SSIS application may be copying a file twice resulting in a partial copy. This leaves me with a guess that the file may be locked, temporarily by the FTP service whilst the client machine is trying to download said file.

Is it possible that IIS FTP in windows server 2012 may be locking the file whilst being downloaded?

Answer 1

Yes, IIS locks the files, when you are downloading them.

It's basically a standard Windows behavior, that files are locked while being worked with.