June 02, 2008, 4:21 PM — You know you need to change the oil in your car every 3,000 miles, clean your
house's gutters every fall, and brush your teeth at least twice a day--but do
you know what's necessary to keep your Mac in good shape? For the most part,
Macs run smoothly. But as with most machines, a little preventative maintenance
goes a long way toward keeping things running smoothly.
This week, in our Essential Mac Maintenance series, I'll show you what you
need to do, starting today with how to Get
Set Up. But first, let's talk about what you don't need to do, despite
what you may read in online forums or on email mailing lists. I call these things
maintenance myths.
Myth #1: "You should repair permissions regularly."
OS X's permissions determine the access each user has to each item on
a hard drive. If certain files have the wrong permissions, you can experience
problems. So you'll commonly hear that you need to use Disk Utility's Repair
Disk Permissions feature on your startup drive as a routine maintenance procedure.
But contrary to popular belief, repairing permissions--a procedure which simply
resets permissions to a known state--works only on a particular subset of OS
X system files. It doesn't affect user files, nor does it affect third-party
files or programs. In other words, it's unlikely that regularly repairing permissions
will prevent problems.
If you ever do have a problem with system-level permissions, your Mac
will likely behave oddly, and you'll usually be able to use the Repair Disk
Permissions function then to fix the problem without any data loss or
long-term effects. So I recommend repairing permissions as a troubleshooting
tool rather than a maintenance task. For a comprehensive look at this topic,
see Repairing
Permissions: What you need to know.
Myth #2: "You need to run the Unix maintenance scripts."
You may have heard about a collection of magical Unix maintenance scripts that
OS X is supposed to run automatically. The story goes that because these scripts
are scheduled to run in the middle of the night, putting your Mac to sleep or
shutting it down prevents them from running--so you need to do so manually.
It's true that there are Unix scripts that perform certain cleanup tasks in
the early morning--one script every day, a second script once a week, and a
third once a month. It's also true that if you shut down your Mac every
night, the scripts don't run. However, the situation isn't as dire as you might
think. First, if you put your Mac to sleep at night, instead of shutting it
down, Leopard is smart enough to run the missed scripts the next time you wake
up your computer. (Tiger is supposed to do so, as well, although this automatic
feature didn't work as well.) Second, the tasks these scripts perform aren't
so important that a few missed executions will adversely affect your Mac.
The main script tasks involve cleaning out old log and temporary files and
rebuilding Unix's locate and whatis databases. If you're a Unix geek, leave
your Mac on (or asleep) on Friday nights so the weekly script can run at its
normal Saturday-morning time. If you're not a heavy users of locate or whatis,
you'll likely be fine running the scripts every few months just to clean up
your log files. An easy way to run the scripts manually is by using Mike Vande
Ven Jr.'s free Maintidget
1.3, a Dashboard widget that shows you the last time each script was run
and lets you manually run one or all with a single click. There are also innumerable
tweaking utilities that provide similar functionality
Myth #3: "You should periodically defragment your hard drive."
If you save a file to your hard drive when there isn't a large-enough block
of contiguous free space for it, the file is broken into several smaller pieces.
This is called file fragmentation. Some amount of file fragmentation
is normal, especially as your hard drive gets full. But too much file fragmentation
hinders performance--the more fragmented your drive is, the harder it has to
work to read each file.
