Like many other places, we ask our users not to save files to their local machines. Instead, we encourage that they be put on a file server so that others (with appropriate permissions) can use them and that the files are backed up properly.

The result of this is that most users have large hard drives that are sitting mainly empty. It's 2010 now. Surely there is a system out there that lets you turn that empty space into a virtual SAN or document library?

What I envision is a client program that is pushed out to users' PCs that coordinates with a central server. The server looks to users just like a normal file server, but instead of keeping entire file contents it merely keeps a record of where those files can be found among various user PCs. It then coordinates with the right clients to serve up file requests. The client software would be able to respond to such requests directly, as well as be smart enough to cache recent files locally. For redundancy the server could make sure files are copied to multiple PCs, perhaps allowing you to define groups in different locations so that an instance of the entire repository lives in each group to protect against a disaster in one building taking down everything else.

Obviously you wouldn't point your database server here, but for simpler things I see several advantages:

• Files can often be transferred from a nearer machine.
• Disk space grows automatically as your company does.
• Should ultimately be cheaper, as you don't need to keep a separate set of disks

I can see a few downsides as well:

• Occasional degradation of user pc performance, if the machine has to serve or accept a large file transfer during a busy period.
• Writes have to be propogated around the network several times (though I suspect this isn't really much of a problem, as reading happens in most places more than writing)
• Still need a way to send a complete copy of the data offsite occasionally, and this would make it very hard to do differentials

Think of this like a cloud storage system that lives entirely within your corporate LAN and makes use of your existing user equipment.

Our old main file server is due for retirement in about 2 years, and I'm looking into replacing it with a small SAN. I'm thinking something like this would be a better fit. As a school, we have a couple computer labs I can leave running that would be perfect for adding a little extra redundancy to the system. Unfortunately, the closest thing I can find is Dienst, and it's just a paper that dates back to 1994. Am I just using the wrong buzzwords in my searches, or does this really not exist? If not, is there a big downside that I'm missing?