About six months ago I laid out my opinions on home-based backup solutions. As my some commenters quickly pointed out, you’re not really backed up until your data resides in more than one place, geographically speaking. That is to say: using scheduled nightly backups to an external hard drive or something like Time Machine is great, but if your house burns down, so does your data.

For the past several months I’ve been getting better acquainted with online (off-site) backup services, as I’ve prepared to reorganize how we store all our data at home. I looked at popular file syncing services like Windows Live Mesh and Dropbox, but those are limited in space (only a few GB) and not really intended for backup. I realized I needed something huge, because I have at least 50GB of must not lose files and something like a terabyte of really would prefer not to lose files. Here’s what our home setup looks like now:

• 1 TB primary everyday work drive (in my main machine…in this case, a 24″ iMac); stores all important documents, photos, etc
• 160GB mobile drive (in a MacBook Pro); contains about 80GB of critical work files which I do not trust our own IT department to properly back up
• 80GB drive in wife’s MacBook, which contains documents and photos important to her
• 1.5 TB D-Link NAS (two 750GB drives) storing non-critical archived media like TV shows, movies, software

So I at least would like to backup the drive in my iMac, the drive in my MacBook Pro, and the drive in my wife’s MacBook, which total around 300GB between them of used space. I’ve already got a 500GB external USB drive for nightly backups of the iMac’s critical files via Time Machine, OS X’s file preservation backup system, and I plan on using SuperDuper to periodically make smart backups of the MacBook and MacBook Pro onto the iMac. But what about getting all that data off-site? Enter the cadre of relatively recent and cheap backup services: Mozy, BackBlaze, Carbonite, and a few others all cost about $5 a month and all offer unlimited — or nearly unlimited — storage space.

I’ve decided on BackBlaze, and while this won’t be a full review because I’m not done backing everything up yet (that review will come later), I can tell you why I chose them. First and foremost, they have a great looking control panel for both Windows and Mac that gets you started really quick — it makes a couple assumptions about what you don’t want to back up, like system files that can just be reinstalled, and the rest is good to go. Despite this rapid setup, the control panel offers plenty of information and options for power users to tweak to their satisfaction. They also, like some of the other companies I looked at, offer a great service where you can (for a fee, of course) have your data overnighted to you on DVDs or a hard drive, in case things go boom and you don’t have time to redownload it all from the BackBlaze servers.

Ah yes, time…when backing up over 300GB via the Internet, it’s clearly going to take a long time. Fortunately, just the initial backup is so lengthy — after that, updates are incremental and (supposedly) nearly instantaneous. Based on my research, that was one big advantage of BackBlaze over a number of the other options — while most of the competitors will upload your changed files on a certain schedule, BackBlaze will do it in the background more or less as it detects changes happening. I’m still doing my initial backup, which will take an extremely long time, so we’ll see if that fact holds true during normal use.

What about security? Hopefully, most of you got some sort of nervous tick at the thought of transmitting so much of your data out into the “cloud”. Fear not…every one of the backup services I researched uses pretty high-strength encryption to encode your files on your computer before they’re ever sent out, and the data connection to the server itself is also encrypted. So you have encrypted files traveling via an encrypted server connection. BackBlaze has a blog post with the nitty-gritty details, but suffice to say the schemes they’re using are good enough for the government and good enough for me.

For years I’ve just been backing up my stuff to whatever extra drives I’ve had laying around at home — if I was doing it at all. I’m being proactive and have chosen to do two layers of backups — one local and one off-site — but I think at the very least everyone should consider trying out one of these online backup services. For only $5 a month (and most of them let you try the first month for free), how can you go wrong? Remember this maxim: your data doesn’t exist until it exists in at least two places.

Full review of BackBlaze to come.