A number of years ago, when the commercial Internet was still young and hard drive capacities were usually measured in megabytes rather than gigabytes or terabytes, I subscribed to an online backup service. For a modest monthly fee, I could back up all my important files to a secure server somewhere out there on the Internet and, without investing in any additional hardware or software, feel certain that my files were safe in the event of any disaster.
Over time, the amount of data most of us had to back up increased dramatically. Conveniently, the availability of affordable, high-speed Internet connections also increased, while the cost of hard drives decreased. Nevertheless, several online backup services, including the one I used, went out of business because they simply couldn't make money. The cost of backing up all that data had increased to the point that few people could justify the price, especially when compared to that of common backup media such as external hard drives and recordable DVDs.
A few of the old-school online backup services held on, but for individuals with large amounts of data to back up, they seldom make financial sense. Besides the cost, there's the issue of time - even with the fastest consumer-grade broadband connection currently available in the United States, it could take weeks to do a full online backup of a moderately large hard disk. Naturally, restoring files takes a long time too, and if your Internet connection happens to die, you're out of luck.
For all these reasons, although I mention online backup services as an option in my book "," I've tended not to recommend them to most people. Over the course of even a few months, you can save considerable money and time by buying two or three inexpensive external hard drives instead. Yes, you'll have to rotate one of them offsite manually from time to time, whereas online backups are inherently stored offsite. But the gain in convenience and control surpasses that minor inconvenience.
Recently, however, the online backup landscape has been changing. Last week I decided to do a survey of currently available options for Mac users, and I found at least. Many of these options are still too expensive, or too limited in their capabilities, to make them strong contenders in my book. But two categories of service have emerged that could make me seriously reconsider my stance. Although they're not yet mature enough to merit unreserved enthusiasm, they are certainly worth looking into.
Price Breakthroughs -- The first category includes two backup services with unusually low costs, but with a full set of backup features. I described one of these, CrashPlan, in " " (2007-02-26). Not only does CrashPlan offer inexpensive online storage, at just $5 per month for 50 GB (and $0.10 per gigabyte thereafter), it also gives you the option of storing your files on a friend's computer, with no monthly cost at all. But now even CrashPlan is getting a run for its money from Berkeley Data Systems' , which offers unlimited storage for the same $5 per month. Mozy's Mac client is new - still in beta testing, pretty buggy, and missing some important features. But I've been in touch with the developer and it sounds like all my complaints are actively being worked on.
When these two programs evolve a bit, I could very well begin recommending one of them as a supplement to hard-drive-based bootable duplicates for most users. Already they're very close to the point where they make more sense than hard drives - in terms of both cost and security - for archives of frequently used files. I also wouldn't be surprised if some of the older, more expensive online backup services find a way to offer services that can compete with these in cost, and I hope they do: the more, the merrier.
Gimme an S! Another category of online backups makes use of  (Simple Storage Service), which provides virtually unlimited online storage space. The price is reasonable: Amazon charges $0.15 per gigabyte per month plus $0.20 per gigabyte uploaded or downloaded. Thus, you pay very little simply to let your data live on their servers, and a bit more to move it there or back. Assuming you transferred an entire 50 GB (one way) in a single month, you'd pay $17.50 to store that data on S3 for a month. That's more than triple the cost of CrashPlan or Mozy, but it costs only $7.50 to store that same data the following month, which is easily in the same ballpark.
S3 provides only storage space, and doesn't even offer an easy way for end users to access that space. In addition, Amazon currently disallows individual files larger than 5 GB, which is problematic not only if you have large files but also if your backup software combines multiple files into a single archive file. In my book I expressed the hope that mainstream backup programs, such as Retrospect and Data Backup, would add direct support for S3 at some point, solving both the access problem and the file size problem at once. They haven't yet, but in the meantime a few other options have appeared.
First is, an application that started out as a way to mount your S3 space as a network volume. Published by Jungle Tools, Jungle Disk has since added some . It can't yet store archives with multiple versions of each file, nor can it perform CrashPlan's neat trick of backing up only the portion of a file that has changed since the last backup, which saves a tremendous amount of time, bandwidth, and storage space. However, these features and more are reportedly in the works. Jungle Disk is free while still in beta testing; it will sell for $20 when it reaches version 1.0.
Maluke's is also in beta testing and also free (final pricing, if not free, is undecided). Unlike the current beta of Jungle Disk, S3 Backup lets you set up several independent backups that are stored in separate folders (or "buckets," in S3 parlance) on Amazon's servers; it also lets you exclude files matching a wildcard pattern. However, it doesn't yet support scheduled backups, while Jungle Disk does.
I don't worry much about the current limitations of these programs because they both clearly have some distance to go before their final releases. However, I should note that neither makes any mention of a mechanism to deal with S3's 5 GB file size limit, and it's unclear whether either will create additive incremental archives in the manner of most desktop backup software.
A third entrant in the S3 category is Xackup's, a service designed to back up your iTunes library. Bandwagon officially launched in mid-February 2007, only to be taken offline within less than a week when the company realized their pricing model (which provided storage on their own servers for a flat annual fee) was unrealistic. They plan to relaunch this month as a front end to S3 and with new pricing. (I discussed the whole launch-unlaunch-relaunch debacle on my blog; see " .") You'll pay between $1 and $3 per month for the use of their software, which they say will eventually back up files besides iTunes content and offer the choice of other storage destinations besides S3.
Back(up) to the Future -- Alert readers will have noticed that of the software I've mentioned here, only CrashPlan is out of beta testing. Although I'm reasonably confident that Amazon isn't going anywhere, I can't comment on the likely long-term reliability or stability of the other companies involved. If you're considering entrusting your backups to one of these companies, that's worth pondering. And although the improved pricing is certainly attractive, it remains to be seen whether it's sustainable. Even if it is, online backups won't be anywhere near as fast as local backups in the foreseeable future, so you have any number of reasons to remain circumspect. However, despite these issues, I find myself cautiously optimistic that online backups are on their way to becoming a reasonable option once again.
Another reason for optimism is that beyond the options I list here, there's a whole raft of other services that offer inexpensive online storage, accessible via such mechanisms as SFTP and WebDAV. Although these services don't include backup software, you can (with a bit of fiddling) get most of them to mount your storage space as a network volume, at which point almost any conventional backup software will work with them. (And several programs can already communicate directly with such servers even if they're not mounted in the Finder. Retrospect, for example, can talk to FTP servers; Intego's Personal Backup X4 can use WebDAV servers.)
Of course, none of these solutions offers the spiffy user interface Apple has promised us in Leopard's Time Machine feature. But then, there may turn out to be a way to store your Time Machine archives using S3 or one of its competitors. I don't know how effective or speedy that would be, but it could be an intriguing option. In any case, it's clear that the backup scene, which seemed eerily static for so long, is rapidly evolving, and anything that makes backups easier, cheaper, or more secure is a good thing.