Cross-posted from the Spanning Backup Blog:
At Spanning, we've been doing sync since 2006. (Damn, that's a long time.) But we hadn't been doing it long before we realized that sync makes backup even more important. Because with sync, when you make a change—including an accidental deletion or modification—that change gets sunc (we made that word up) to all of your copies of that data. So if you sync everything everywhere, your changes, including screwups, affect everything. Everywhere.
In March 2007 we shipped Spanning Sync v1.0, which for the first time let users sync their Google calendars with iCal. Soon tens of thousands of people were using it to do for their calendars what apps like Dropbox now do for files. People could connect multiple Macs to a single Google account with Spanning Sync and have changes made on any of them show up on all of them—and on Google. It was awesome, and there was much rejoicing.
But just a few months later Apple shipped OS X 10.5 "Leopard", and something very bad happened. Inexplicably, Apple made a few changes to Leopard between the final developer release (against which we had been testing) and the bits they shipped to customers. And one of those changes caused Apple Sync Services to tell all sync clients (including Spanning Sync), "Delete everything!" And we did. We had become Death, the destroyer of worlds.
Luckily it didn't take us long to figure out what was going on. We shut down our servers so no more bad delete commands would be sunc and worked through the night digging through log files to manually recover lost data for our affected customers. It wasn't pretty, and it wasn't fun. We updated our app to work around the problem and issued a fix within 48 hours. Disaster was averted but the experience stuck with us. And it led us to develop Spanning Backup for Google Apps.
So here we are in 2012 and sync is hotter than ever. Dropbox has some crazy ten-digit valuation, Apple is syncing data among all their own devices willy-nilly with iCloud, and the mighty Google is rumored to soon be launching something that may or may not be called Google Drive. But whatever it's called, I bet it's going to be awesome. And there will be much rejoicing. But.
But like the roads of the Roman Empire that enabled not only commerce but also hordes of marauding barbarians, sync is a two-way street. (See what I did there?) It enables not only easy sharing but also easy accidental data loss. Delete something here and—poof!—it's gone everywhere.
Sync makes backup even more important.
For my part, I'm loving the sync-everything-everywhere lifestyle. Dropbox is awesome. Google Drive will hopefully be awesomer. And along with tens of thousands of other people (thank you all!) I continue to use Spanning Sync (because it's still way better than the alternatives). But I'm more careful than ever to back that stuff up.