I’ve read speculation about Scrivener being incompatible with Time Machine and Dropbox (which I don’t use).
Is there a definitive statement from the development team?
– Kay
It depends what you mean by “compatible”. Scrivener .scriv files are essentially folders of files, and Dropbox will happily rename files in folders to avoid conflicts, which might happen if the same files are open on two computers at the same time. If it does this, you might find that a project will no longer open, although it’s usually easy to fix. The recommended option is to backup to Dropbox using File > Backup To with the zip option checked rather than working directly from your Dropbox folder. This ensures conflicts will not arise.
As for Time Machine, I’ve never used it so cannot comment for certain, but I believe that the problem is that it only saves changed files in any given folder, and so if it treates .scriv packages as folders it could take incomplete snapshots of the files, meaning that a restored project may not open or contain all information. Perhaps someone who uses Time Machine can clarify how they have found it to work with Scrivener, though - given that file packages such as .scriv files are something unique to the Mac and introduced by Apple, it would be remiss of Time Machine not to support them properly.
Hope that helps.
All the best,
Keith
I don’t use Time Machine, but I do use Dropbox to back up (rather than sync files between two computers).
I don’t work directly from Scrivener files kept in my Dropbox folder. I think that’s too risky, in case Dropbox syncs as Scrivener is saving to the folder and so corrupts my work. Instead I zip up back-ups, using the command in the Scrivener file menu, and direct them to the folder.
This thread, especially the early posts, explains.
Edit: Ah! Repeated Keith.
The problem with Time Machine is pretty basic and easy to get around, and is based on the same premise that advises against moving projects that are open. While a Scrivener project is open, it is in a different state than when it is closed. So when Time Machine comes along and records the changes that have been made to the Scrivener project in the past hour, it records the project in its “open state”. Thus, if you have a crash or something and need to restore, if you restore from that specific Time Machine period, the resulting project will be “open” and you will get a warning message from Scrivener and have to resynchronise strings.
It is true that Time Machine only stores the parts of the project that have changed, but this is desirable and the Time Machine interface is designed to work with that. Since it only saves the bits that have changed, it saves a tremendous amount of hard drive space over time. Consider a 1gb Scrivener project where you’ve only changed a single word in one synopsis. Time Machine will note that one synopsis text file has changed, and record that in Time Machine. If you were to manually open that copy of the project, the only file in it would be that synopsis .txt file. 
So yes, if you tried to restore by going into your TM drive and dragging the project out, you’d get a mess. The Time Machine software though is designed to work in these “temporal layers” if you will. It will recreate a complete project from all of the scattered fragments that have changed over time, resulting in a complete, 1gb project file.
The key is to make sure that you periodically let Time Machine run with your Scrivener projects closed. So long as that happens on a regular basis, you’ll be safe. Where Time Machine can be unreliable is when you leave projects open for weeks or months on end. In that case, it might be conceivable that you have no good “closed state” project copies backed up.
To add a tiny bit to AmberV’s insight, you should do this on a daily basis to make Scrivener projects work with Time machine:
At the end of every day, when you are ready to shut your computer down (or put it to sleep, stash it in your breifcase, etc…), close Scrivener, and force a final Time Machine backup (“Back up now” from the time machine menu bar icon). The last backup of each day (before midnight) is the one that is saved when Time Machine throws out the hourly backups from over 24 hours ago, so each daily and weekly backup will be pristine if you follow this routine.