There's no question that you should back up your irreplaceable documents and digital media. The statistics point unwaveringly to the likelihood of your disk crashing or some other mishap befalling your data. And online backup services offer perhaps the best way to assure their safety, since they store the data on remote, redundant servers. Today's online backup services make prevention of data loss automatic, secure, and affordable.

These services have you install software on the PCs or Macs you want to protect, scanning the hard drive for all files that make sense to back up. They then compress and encrypt the files and upload the data to their server farms at multiple redundant datacenters protected by military-grade security. But of the dozens of services available, how do you choose the one that best meets your needs?

The concept seems simple on the face of it—regularly upload your important files to a service's secure servers, and in the event you lose said files, downloading them back again. But the number of variations on this theme is striking: Do you want a local backup software that works together with the online service? Do you need file syncing? Version saving? Mobile access? The list goes on. But the first thing to decide is how much data you have to back up and how many computers do I have to back up?

Price
Since all of the services have the same basic function—securely upload your files to their servers for you to get at when your PC goes south—price should be a factor in your decision. For $50 to $150 a year, you can protect as much data as your computer holds with an unlimited storage service such as Carbonite or Backblaze. But these unlimited plans come with a hitch—they'll only protect the files on a single computer.

Most digital households today boast more than one PC these days, so services that allow more than one PC in an account, such as SOS Online Backup Visit Site at SOS Online Backup, are often preferable. Some services, such as CrashPlan, use third-party server farms, such as Amazon S3, and charge you per GB, which can complicate your bill. Do the math to see whether this kind of plan makes sense for the amount of data you need to back up. CrashPlan also offers the unique ability to use an Internet-connected friend's hard drive as your backup target, which saves on storage charges.

If you just want to safeguard a few loose documents or photos, you can take advantage of free accounts. Mozy offers a free account with the 2GB of storage, while IDrive and AVG LiveKive offer 5GB free, and MiMedia ups the ante to 7GB. For full protection of a typical multi-computer household, you'll need a paid account. The table below shows how several online backup players stack up both by their stated pricing and how much it costs to protect 150GB of files on three computers:

Choosing Files for Backup
Selecting your online backup service is about more than just how much you'll pay per year. The first things to consider is how it chooses—or lets you choose—what to back up. Most services these days will automatically select the standard Windows My Documents or Mac user folders. And most let you fine-tune this selection, usually using a program window with a folder and file directory tree, with check boxes for selecting exactly the folders and files you want backed up.

Some services go deeper into the operating system, adding choices to the right-click menu options for backing up, restoring, or removing file from your online backup set. These can be handy if you have an important file that you want backed up immediately. All of the services install a System Tray icon that gives access to the program window or at least to launch a browser, if the service uses that as its interface, as Norton Online Backup does. The tray icon should let you start a backup or restore immediately.

All of the services use encryption on your files when storing them on the servers. Many of the services even let you be the sole possessor of the password that protects your data, so that top-secret stuff can't even be accessed by the online service employees themselves. But only use this option if you're dead sure you won't lose the password.

When to Backup
There are two camps in how an online backup service decides when to perform its work. The first is scheduled. This one is pretty obvious: You tell the service's software how often and when you'd like the backup processing and uploading to take place. Usually this will be in the wee hours. The second camp is the continuous backup camp. Some services, like our Editors' Choice SOS Online backup, offer a hybrid of both, letting you specify individual files that must be watched all the time and backed up as soon as any changes occur.

The advantage of a scheduled backup is that it leaves your entire Internet connection bandwidth to you while it's not running, while an always-running-in-the-background service necessarily drains off some of that bandwidth. If you're worried about bandwidth, go with a scheduling service, and if you're more concerned about having every file saved at every moment, the continual service, such as Backblaze and Carbonite, are for you.

Any large backup upload can take time, days, even weeks for dozens of gigabytes of data, depending on the speed of your Internet connection. But luckily, that's only the first time. The majority of the services only need to upload the changed parts of a file thereafter, so subsequent "full backups" will take much less time.—Next: Restoring and Extras >