So you've got your carefully labeled hard drives, DVDs, or other media with freshly recorded data. Now what?
Taking care of your media is just as important as making proper backups in the first place. If the media is lost or damaged, it does you no good. So I want to say a few words about handling, storing, and caring for backup media.
Whether you use hard drives, optical discs, or another type of media, the same general rules apply: store them in a cool, dry place away from significant sources of light, static electricity, vibration, and other hazards (such as inquisitive pets or children). All this may seem obvious, but it pays to remember that you're doing backups in the first place because your data is valuableperhaps even irreplaceable. So treat your media with care.
For extra safety, store your media in a container that's rated fireproof for media.
Recycling vs. Long-Term Archives
If you use hard drives for backups, sooner or later they will fill up. (Whether this takes a few months or a few years depends on the rate at which you accumulate new data and the size of your backup disks.) And if you use lower-capacity removable media, sooner or later you will have a stack so large it threatens to collapse under its own weight. When this happens, you have two options: buy completely new media and start over, or recycle.By "recycle" I don't mean throw your backups in a blue binI mean erase the media and reuse it for a new set of backups.
One argument for starting fresh is that new media is virtually always more reliable than old media. Another is that you can save your old media as a long-term archive, in case you need to see what was on your computer a few years ago. On the other hand, recycling media saves money, not to mention physical storage space. And most people have little need for backups stretching back more than a couple of years.
The cost of buying a new stack of DVD-R discs is, of course, much lower than the cost of buying new hard drives. In addition, as I mentioned earlier, hard drives make a poor choice for long-term storage (though an older hard drive that you wouldn't trust for backups may be fine for casual, non-critical uses). So, if you use hard disks to store your backups, you should recycle instead of replace. However, remember that hard drives don't last forevereven if they're just sitting on a shelf, your data will deteriorate over time. A reasonable compromise may be to recycle your hard drives once a year or so for 3 or 4 years, and then replace it. If, when it comes time to erase your drives, you still wish to maintain a copy of the old data, use your backup software to duplicate your archives onto a stack of DVDs first.
If you're erasing a hard disk anyway, this is a good time to reassess partition sizes (see Does Size Matter?, page 118). If your hard disk or home folder is significantly larger than before, consider changing the partition sizes to better accommodate your current needs.
Be careful when erasing a hard disk that contains months or years of backupsespecially if you chose not to copy its data onto optical media. For safety, erase just one disk at a time, then perform (and test) regular backups for 1 or 2 weeks before erasing the next disk. If you erase all your backups at once, you're inviting trouble.
Raise your right hand, place your left hand on the nearest sacred text (such as The Macintosh Bible), and repeat after me:
I hereby solemnly swear that henceforth, I will at all times maintain a recent, complete set of backup media off-site.
Good. Now I'm going to tell you why you just made such a promise and how to keep it.
No matter how diligently you back up, if something happens to your backup media, you're in trouble. Now, it is safer to keep your backups on an external volume than on, say, another partition of your internal hard disk. But as long as the media on which your backup is stored is physically located near your computer, your data is unsafe. Consider for a moment the range of events that could wipe out both your internal hard drive and any backups in the same area at the same time: fire, flood, earthquake, hurricane, tornado, burglary, destruction by rambunctious children or pets, wayward meteorites. These things all seem so unlikely until they happen to you. Insurance may enable you to replace your hardware and software, but not your data. So please take seriously my advice to keep at least one set of backups off-site, by which I mean in a different building.
The best approach is to rotate multiple sets of backup media, so that you always have one near your computer and another stored safely somewhere else. Periodically (say, once a week), bring the off-site media back, adding it to your normal backup routine so that it can be updatedand take your most recent local backup off-site.
When it's time to replace a hard drive completely, you may consider giving away or selling your old drive. Before doing so, be sure to securely erase it so that its new owner cannot use a file recovery program to retrieve all your data! Merely dragging files to the Trash will not erase the data in such a way that it cannot be recovered. Even the default Erase feature in Disk Utility won't do the trick. Instead, use a tool that can overwrite the entire disk (including free space, not just particular files) multiple times with random ones and zeroes. Clicking the Options button in Disk Utility's Erase pane provides two ways to zero the data. Other examples of products that include this capability are:
Although you can use this process with just two sets of media, having three makes it more convenient. At any given time, you'll have one set (A) in use, your next-most-recent set (B) on site, and your oldest set (C) off-site. When you rotate the media, you bring your oldest set (C) back on site and make it active, taking what has now become the oldest set (B) off-siteand so on. For maximum safety, if you use only two sets, don't bring your off-site backup media back to your home or office until after you've taken another set away; those few hours when all your media is in one place could be the time when disaster strikes.
You may be wondering where exactly "off-site" could be in your case. Here are some suggestions:
Don't keep an off-site backup in your car, which is if anything more susceptible to damage or theft than your home. Heat and cold extremes in your car can also hasten data corruption. If you want as much security as possible with a trade-off of less convenience, keep it in a safe deposit box at your local bank.
Warning! Because hard disk-based duplicates are, by definition, unencrypted, storing them off-site presents a significant security risk: anyone who obtains the drive also has complete access to your data. Here are some ways of reducing that risk: