Information Technology Reference
Decide How Many Drives to Buy
You'll need at least one hard drive (in addition to a Time Capsule,
if you have one). A single hard drive might meet your backup needs
perfectly; however, your backup drive could break down or get stolen,
leaving you with no backups. So for extra safety, I suggest having a
secondary backup of some sort that can be kept in another location.
One way to get that secondary backup is to use an Internet backup
service, as I describe in Store an Extra Backup Offsite . If that's the
way you choose to go, you can get by with a single external drive and
not significantly compromise your data safety.
Another way to get a secondary backup is to buy another drive and
then switch between the two drives every so often, moving one of
them offsite each time. In that case, the optimal number of hard drives
is two. Of course, you can do lots of useful things with a drive besides
storing backups, so having a second one, on general principle, is not
a terrible idea.
Note: Although you can use a spare hard drive for many things
besides backups, I recommend that you don't mix backups and other
data on any given partition. There's no technical reason this wouldn't
work, but you increase the risk of accidentally deleting or overwriting
If you want to be extraordinarily cautious, or if you're paranoid, or if
you've had bad experiences with hard drive failures, then you could go
a step further and get three hard drives. (I think three is excessive for
most people these days.)
But before you hand over your credit card, you might want to skim
through the rest of this chapter to explore other hardware options.