Information Technology Reference
hour. CrashPlan+ can detect when files change and then back them
up immediately (or after a delay that you specify, such as 15 minutes).
And Retrospect has a mode (called Proactive Backup) in which it runs
as often as needed, giving you more flexibility than with conventional
schedules. Numerous other programs offer variations on this theme.
All things being equal, I prefer schedule-free backups (of whatever
sort), because they require less setup and maintenance work, and they
increase the probability that your backups will happen when they
should. But if your backup software doesn't offer that option, you'll
have to manually set up a recurring schedule, as I describe next.
In cases where you must schedule a backup explicitly, when should you
schedule it to run?
Some backup programs can slow down your computer significantly
while backups are running. This could be an argument for scheduling
backups for when you're not using the machine. However, if you do not
leave your computer on all the time, you will need to take special care
to ensure that it's on and ready when the backups are scheduled to run
(see the sidebar Power Management and Backups for more details).
How often should you back up your Mac? And if you're making both
duplicates and versioned backups, how often should you update each?
No single answer is right for everyone, but my rule of thumb is that
duplicates should be updated at least once a month, and versioned
backups should be updated at least once every day that you make
minor changes (receiving email, modifying text files, and so on). Thus,
if you use your Mac heavily every day, and often install new software,
you might opt for weekly updates of your duplicates and daily updates
of your versioned backups.
More frequent updates, of course, are even better. For anyone with
a reasonably fast Mac, an external hard drive, and modern backup
software, there's no good reason not to do backups as frequently as
possible. (I have two different kinds of versioned backups running