There are nearly as many ways to back up your business data as there are ways to lose the data and require that backup. Some businesses still use venerable tape backups, others hard disks, perhaps DVDs, or increasingly, the cloud and remote storage facilities. No matter which medium you use, the principles of data backup are the same, and it's important to understand which data needs to get backed up, how often, and for how long.
The first step is pure common sense, yet it is frequently skipped: Conduct a thorough analysis and inventory of existing systems with a focus on data storage. It will be tedious, but you need to catalogue the location, owner, and importance of each bit of data.
The alternative is to back up everything, wasting time by writing extraneous files and wasting money on extra media.
A good place to start is simply by listing the directories on each server or storage device in a spreadsheet, and then adding columns for the type of data in that directory (the content, not the file type – "Contracts" or "Bookmarks," not DOC or XLS), the owner (who would care if the files were deleted), and whether they are essential to your business. In a more complex environment – for example, an online business that has no off-hours – add another column for a time when no one is using the file and it can be backed up.
This brings up an interesting question: What is essential to your business? For a simple answer, ask yourself: "If I lose that file, could I lose money?" Note that the question is could rather than would; this casts a wider net – better safe than sorry. Next consider your backup schedule; there's a whole theory and science to backup rotations.
There are three common methods. A full backup includes all files whether they have been changed or not; differential includes all files changed since the last full backup; and incremental includes only those files that have changed since the last backup of any kind. Beyond that, here's some sound, basic advice for proper business backup.
Better backup strategies
Save your backups for longer than you think you have to – something unexpected always comes up. (Why is it still unexpected? No one knows.) I tend to use an adapted version of Grandfather-Father-Son: I call every third Grandfather an archive and don't overwrite it.
Test your backups
Like many of my clients, I have learned the hard way that just because you set up a job, load a tape, run the job, and even read a successful report does not mean that files were actually backed up. Tapes fail (they are mechanical), files are locked and can't be copied, and software errors do occur. Frankly, backup software is notorious for reporting that everything is satisfactory when in fact the job has failed.
As a failsafe, at least once a month, you should select a few files at random and restore them, making sure not to overwrite newer versions. Then open the files and confirm that they are intact and usable. If you find that they aren't, you have time to address the problem before an emergency arises. Make sure that you do so.
Always keep some sort of backup off-site
The reason for off-site backup is simple: If something physically catastrophic happens at your place of work and your backups are there, they will be rendered inaccessible or destroyed. Store your off-site backup securely, in a lockbox or safe, and update it with a current backup every six months. Protecting something just long enough for someone to steal (or something to destroy) every bit of data your company cherishes is not going to help you.