Is the failure you are getting an empty zip file?
I chatted with @issa about this and it seems likely that your original hypothesis about memory is correct. Specifically, reading media files out of the database to build the zip can fill available memory. Unfortunately, there's no way to detect that case and provide a more helpful error message so you just end up with an empty zip file.
This is documented in the obtaining a server docs:
If you don't expect many forms to be submitted at once and you don't expect many large media attachments, you can start with 1GB. Higher-load servers and servers which handle many image or video attachments may need 2GB or more. It is pretty easy to upgrade to a larger size later.
It might be helpful to pull this text out into a note and possibly to mention the empty zip file so users can more easily identify that this is the problem they experience.
Some options:
- limit the size of your images in the form design by using
max-pixels - keep using Briefcase
- upgrade to 2gb of RAM (costs $5 more a month)
- add swap
We haven't tried adding swap so if you do try it, please report back on performance. Note that we would not encourage anyone to rely on swap constantly. We recommend a swappiness property of 0 so that it is only used when absolutely necessary.