[Mayan EDMS: 2115] How does Mayan store files?

[Hans Fritz]

I'm very surprised as I uploaded about 2GB of pdf files into Mayan. These
PDFs are scanned images (grayscale 300dpi) cleaned with textcleaner to make
OCR work better. It comes down to about 1MB per page.

Mayan has been processing the uploads for the last 11 hours now (my server
is a bit old), but what worries me is how much space it uses. The
mayan/media/document_storage directory is 3.8GB (it's possible I have
duplicates, I'd have to check once it's done processing), and the
mayan/media/document_cache is 16GB and growing.

What's in the cache that's taking so much space? Is it the JPEG
thumbnails/preview of pages? If so, is there a setting somewhere for the
JPEG quality? I don't need amazing quality for the previews, I'd rather
save the space and processing time.