Bernt, the situation looks bad.
Apple engineers recommend that one keep at least 15-20% of the boot hard drive or partition capacity as free space. The reason is that the operating system, and often applications as well, need to write temporary, cache or swap files to the disk.
Although OS X is normally well-behaved, when there’s no more free space on the disk the operating system can continue to write to disk. In doing so, it overwrites existing files. The same problem results if your application writes to disk. Result: disaster.
It’s a good idea to periodically review the disk usage on your drive. Activity Monitor has a tab to allow this. Try to keep a reasonable amount of free space on the drive. Perhaps you can archive to a CD or external drive some of the files that you don’t need on a frequent basis.
Or get a larger hard drive. They continue to get cheaper and bigger.
Periodically, at a time when I’m sure my database is in good shape, I make an external backup using Scripts > Export > Backup archive. But that “belt and suspenders” recommendation wouldn’t have worked in the case of a drive with not enough free space (unless you mounted an external drive and saved the archive backup to that drive).
Comment: I hate to see new users approach DT Pro as a Finder replacement and drop everything on their hard drive into the database. First, that approach is dangerous if there’s not sufficient free space on the hard drive. (Bernt, this rant isn’t directed at you. I’m working up a collection of tips on how to use DT Pro effectively.)
More importantly, it’s usually not the most efficient or effective use of DT Pro for its primary purpose, as an intelligent assistant for managing and using document collections. I’ve got hundreds of gigabytes of documents on my PowerMac. If I dumped all of them into a single DT Pro database it would become very large and somewhat unwieldy, even on my “hot” machine with 5 GB RAM and dual processors.
Instead, I focus on my topical interests. I have a large collection of documents related to environmental science and technology topics, reflecting my professional interests in those topics and special interests in environmental science/policy exchanges with developing countries. So I put that material into my “main” DT Pro database. It’s pretty large, about 20,000 documents and 20,000,000 words content. But most of my searches take 50 milliseconds or less, so it’s fast. Because the content of my collection does have meaningful/contextual relationships (both to me and to DT Pro), using See Also to follow a trail of contextual relationships of documents really does work, and it’s fast. So this database is enormously useful to me.
I have a Newton 2100. I’ve been subscribing to Newton list-servs for years. I’ve got a huge collection about the Newton. That goes into a separate DT Pro database. That one is fast, too. But it has no meaningful relationship to my main database. If I melded the two, the combined database would become less useful and would probably slow down.
And I’ve got a number of other DT Pro databases. For example, I’ve got scanned records of taxes paid, purchases/warranties, etc. Putting that material into a DT Pro database means that I’ve got very quick access to it. But I don’t put that stuff into my “main” database, except perhaps temporarily. If some of it is in my main database I will periodically export/import it into a more appropriate database and delete it from the main database.
I’ve got a big collection of TV videos, including all the episodes of Monk and a lot of Alfred Hitchcock shows. It would make no sense to also dump that into my main database; iTunes does a good job of managing that material. But I’ve got a few QuickTime moves related to my environmental exchange interests, and those do get indexed into my main database. I take a similar approach with image files. Most of them are managed in iPhoto or in separate Finder folders. But I’ve got some photos I took of a polluted lake near Alexandria, Egypt. That’s an example of some image material that I will also index into my main database, as it’s topically related. But I don’t include photos of a trip to Glacier National Park in my main database (unless I’m on a project to document the melting of glaciers).
DT Pro makes it easy to create and switch between databases. That’s a big advantage over DT Personal.
General advice: Think about what you would like to accomplish in improving your access to and analysis of the information on your computer. Recognize the limitations of your computer (even the fastest ones available), as some of the features that make DT Pro very powerful are demanding of your computer’s resources, especially memory. You probably have several topical interests reflected in the material on your computer. Think about those interests in designing your databases. That approach will likely make DT Pro a joy to use.