I'm going to try and keep my request very specific to hopefully keep the discussion on track. Can someone provide an explanation on how disk space is related to Moodle 2.0's file handling? I'm hoping that someone can articulate why/how the following statement from Moodledocs is true :
"In Moodle 2.0, files are stored only once, saving disk space."
How does this (non-exponentially increasing disk usage) actually work when, from the teacher's perspective, files are copied from one resource to another (creating multiple copies of the same file) when they are used in multiple places?
Thanks to all for their hard work in explaining file handling - Looking forward to helping my teachers understand!
AFAIK, the essence is simple. Images and other files used in a course are uploaded to a single repository, then what is used in the course is a link to that repository. The link is created via the database that the course uses. If someone else uses the same image, or is importing elements of a course to another, what is essentially happening is that there is no assett transfer, only the notional transfer of the link kept in the database. e.g. Instead of a 500kb image a 50byte link is transferred. This system works fine, as long as the original image is available. If someone deletes the original course, then there may be a problem.
I may be wrong on this, but it is very much a swings and roundabouts thing, there are some advantages, eg picking up disk space, but some thoughtlessness, or lack of understanding to be more precise, can cause dramas for other courses. I can see a whole new set of rules about using repositories developing in the future.
Hi Drew and Colin
As I understand it, Moodle stores the files in a single repository and keeps track of which files in the repository that is in use. If you delete a course or an activity in which the file is used, only the course or activity will be deleted. After a few days Moodle will delete the file too if it is not used elsewhere. Every time you use a file a new link to it is created, this is what is known as 'copy'. So the file is actually not copied, the 'copying' can be thought of as hard symlinks (thanks to David Mudrák).
I'm starting to be confused by this as well. If I need to make the same file available in two courses, and the first time it comes from Dropbox:
1. Should it appear in "Recent files" when I try to upload into the second course?
2. If not, and I have to re-upload it from Dropbox, doesn't that make two copies of the file?