Update (11 March 2009): Microsoft has retired FolderShare in favor of Windows Live Sync. It’s basically the same service, except they’ve significantly increased the file limit per library and finally added full Unicode support. Now that my two major gripes with the service are resolved I’m perfectly happy with Sync, and it’s free to boot!

I have a very large collection of music files, easily 70GB with thousands of files (those lossless rips can be quite space-consuming). I listen to music both at home and at work, and don't want to go through the trouble of synchronizing these collections manually. In fact, I would like a service that fulfills the following requirements:

• Easy to set up;
• Works across NAT, preferably with UPnP support;
• Full Unicode support;
• No artificial limit on library size;
• Not required, but definitely advantageous:
  • Free;
  • Low memory and CPU overhead;
  • Libraries are accessible over the web;
  • Some sort of online backup solution

The NAT support is an absolute must, as I have little or no control over the firewall at work. Unicode support may sound like a trivial requirement, but as you'll see most solutions do not properly support Unicode. My collection contains albums in multiple languages, including Hebrew, Japanese and Norsk, but even English albums can cause issues (Blue Öyster Cult, for example).

I've tested the following solutions:

Although this is one of the oldest players in the game (the company was bought out by Microsoft in 2005) it hasn't seen any visible improvement in a very long time. Despite the apparent dormant development, the service itself works well and is very consistent and reliable. What separates FolderShare from any other solution I've tested is a very user-centric design: any reasonably literate computer user (read: knows what files are and can double-click on an install button) should be able to set up a FolderShare account and start synchronizing files literally in minutes. Once set up the service simply works; other than the disadvantages which I'll enumerate momentarily, I've had absolutely zero problems with the service in over a year of use (well, to be honest there was a highly-publicized two-week service outtage over a year ago, but it's been hassle-free before and since).

FolderShare fails in two specific ways: it's limited to 10,000 files per library (I think there's a limit on the number of libraries supported, but I've never come close to it), and it does not properly support Unicode. This means that files with characters outside the ANSI character set and machine codepage simply do not get synchronized. Other than that its interface is amazingly limited with very few customizable options, but in my opinion this isn't really an issue because the software simply does its job really well.

With these disadvantages in mind, I wouldn't hesitate to recommend FolderShare to English speakers (or ones that do not make use of non-Latin file names), but the rest of us will have to look elsewhere. With Unicode support I'd definitely go back to FolderShare though, it's an excellent product.

PowerFolder

Touted as an open-source file synchronization solution, PowerFolder utterly failed to impress me; it appears to be a very powerful solution, but consequently suffers from a very cluttered UI that's hard to grok. I wouldn't recommend this service to casual users, and it wasn't trivial for me (as a software developer) to figure out either.

I installed a trial version of PowerFolder Pro on both machines, but once I got past the strange UI idioms I just couldn't get the software to work reliably. I managed to send an invitation from one machine to the next (synchronized directories in PowerFolder do not appear to be centrally managed), but couldn't figure out how to get them to sync reliably nor how to resolve file conflicts. Finally, the client software is a real memory hog.

BeInSync

Fairly similar to PowerFolder (with additional online backup features on Amazon's S3 storage service), BeInSync is a commercial product that appears to provide all of the features I require. The service was fairly easy to set up, although not nearly as streamlined as FolderShare. I got my directories to synchronize properly and was relieved to find that Unicode is fully supported by this product.

Despite the promising start, my experience with this product was far from satisfactory: the client UI is incredibly slow and non-responsive. Other than general slowness in rendering speed and bizarre UI idioms (for example, the only way to get a reasonable status display is via the View menu), resolving synchronization conflicts can easily take 30 seconds per file with no batching capabilities at all. On top of that the client software is a major resource hog, easily taking up 60MB and more resident memory, and for a reason I couldn't figure out I could see 3-9MB per second I/O activity from the client although it exhibits no synchronization activity. To add insult to injury, the uninstall program requested that I restart my computer - nitpicking, I know, but what the hell?

Having tested three different services I'm sorely tempted to go back to FolderShare and figure our a manual synchronization scheme for the Unicode files. The other alternative is a homebrew VPN+robocopy/rsync/SyncToy solution which I'd prefer to avoid. I'm rather surprised that it's so hard to find hassle-free synchronization services so late in the game...