For those who love Journaled File Systems ...

[Solar]

Just a quick one before I head for the weekend, regarding "importance" of files - I'd base "importance" on frequency of write accesses, date of last write, and date of last read. I think that might be better than some by-filetype-lookup. Just an idea.

Gotta run.

[Pype.Clicker]

i don't agree, Solar ... my /var/log/messages is accessed far more often than any of my home-cooked .html files and yet it is less important to me ...

[Candy]

I mean i'm probably unlikely to be happy if some 'deleted-but-still-recoverable' documents become unrecoverable because the system lacks space for downloading a DiVx, right ?
Especially if those documents are my thesis (you know, that word file i'm editting for about 3 years now )

I seriously doubt that you are going to make that clearer. By the time the computer starts erasing your thesis for space, you're seriously cramped. The computer should warn you for low disk space a lot sooner. And still, if you intentionally delete your thesis, it's still your own fault. When the space is needed, and you've deleted your file, you cannot expect the filesystem to trick its way around that. Best-effort IMO shouldn't extend that far.

I'd suggest that each file get a sort of "importance level" which can be set automatically using some heuristics (the program that created the file, the user that made it, the mime type of the file, the importance of the "directory" where it is stored, etc.) and that can be adjusted manually by the user (perhaps using some 'tags' UI)

When disk space is missing for a specific task, the system can automatically permanently delete any file that has a 'lower' importance than your current task, but user agreement should be asked before "equal" or "more" important files are permanently deleted (of course, only among files selected for deletion).

The only trouble here is that the 'importance' is actually computed while the file is "alive" and used when the file has been 'scheduled' for deletion by the user ...

That won't work. First of all, everybody thinks his files are a lot more important than other people's files. I've seen people consider their mp3's more important than their friends documents...

On the other hand, huge documents I download from some server in the US are less important than mp3's I've made from my own LP's. No computer can ever judge that as good as I can, but the entire point of deleting a file is that you say you don't need it anymore. Undeletion is correction of a human error and can only be done on a best-effort base.

[Solar]

i don't agree, Solar ... my /var/log/messages is accessed far more often than any of my home-cooked .html files and yet it is less important to me ...

Hargl...

Why can't you guys leave a quick idea alone?

OK, I implied that log files would mostly be rotating anyways.

And, I know people that run webservers who would much rather sacrifice their entire home directories than losing /var/log/...

Sheesh. Why can't there be a "message flag" in forums like these which you can set to "I'm BRAINSTORMING, damnit" or "...on a very high level..." or something like that?