Right now, as I’m flat broke, I’m getting ready to publish my game on itch. Should I have the packager generate pak file chunks, or just one pak file?
The reason I ask this is for patching down the road.
It seems to me that having chunks would mean that only the affected chunks would need to be sent to the user, instead of always needing a big pak file.
Or maybe I don’t understand the PAK files. I’m a developer. Not a packager. 
-Marc
Short answer: chunks aren’t what makes patching small. Unreal’s .pak files are only the container, and a client has to download whatever file changed. For itch.io, the butler tool is what matters. It patches at the binary level, so even one big pak only uploads/downloads the changed blocks, as long as the pak is built deterministically and your content doesn’t shift around a lot between builds.
Chunking (Project Settings > Packaging > “Generate Chunks”, plus assigning assets to chunk IDs with Primary Asset Labels or a Primary Asset Rules Override) is meant for splitting content that ships separately: DLC, optional language packs, streamed levels. It also gets you more files to manage and more ways to get a mount-order mistake.
For a small itch release I’d do this:
Also keep “Use Pak File” on and test a patch cycle with a dummy change before launch.
Thanks! That was helpful information. I have the game online (As of last night at about 1am) and used butler to get it to itch as the game .zip is 2.5 GB and butler was the only thing that would allow me to upload it.
-Marc