Things You Must Know to When Connecting a USB Hard Drive to AirPort Extreme
by Alan Zisman (c)
published in Low
June 29 2009, ZisMac column
Time Capsule, building the equivalents of an AirPort Extreme router and
either a 500 GB or 1 TB hard drive into a single unit, is a
space-saving and easy-to-use way for users to combine a wireless base
station and storage accessible over a home or small business network -
and even across the Internet.
However, many users already have
either a wireless base station (also referred to as a wireless router)
or an external hard drive - or both. And Time Capsule is a relatively
expensive way to add storage, even when added to the price of Apple's
high-end AirPort Extreme.
Apple's US online store lists the
AirPort Extreme base station (with no built-in storage) for $179. A
Time Capsule with a 500 GB drive boosts the price to $299; the 1 TB
model jumps to $499.
I have an AirPort Extreme; until recently,
I'd been connecting a generic 500 GB external USB drive to my iMac and
using it to back up both the iMac and my MacBook using OS X 10.5's Time
Machine backup software. (See my article Time
Machine Can Now Backup to a Shared Hard Drive
backing up two Macs to that 500 GB drive, I'd started to run low on
drive space. Dell Canada, however, had an external 1.5 GB drive on sale
for C$150 (about US$130), which seemed like a nice price for quite a
bit more storage space. Rather than connect it directly to the iMac,
however, I thought I would see about connecting it to the AirPort
Extreme's built-in USB port, making what sometimes is referred to as an
Apple describes what it calls AirPort Disk
as "a simple and convenient way to share files among everyone in your
family, office, or class", claiming "just connect the external hard
drive to . . . your AirPort Extreme and - voilą".
It's not quite
that simple, as I discovered. It is relatively straightforward, but
there are a few under-documented things to be aware of along the way.
(None of these steps are mentioned in the AirPort Extreme User Guide,
1. Partition the Drive
for Mac Use
most external hard drives not specifically aimed at Mac users, the Dell
drive - a Seagate FreeAgent model - came formatted as a Windows NTFS
partition. (Seagate also offers FreeAgent models aimed at the Mac
market.) That's not a bad choice, making the drive instantly usable by
the largest market segment, but it won't be accessible connected to the
Instead, the drive needs to be repartitioned
using Apple's Disk Utility. That means connecting it to a Mac's USB
port and opening the Disk Utility program (in Applications >
Utilities). In Disk Utility, select the external drive and click on the
Click on Volume Scheme to drop down a list of options, selecting 1 Partition
. Change the Format to Mac OS Extended (Journaled).
that was enough, I'd clicked Apply... but the resulting drive wasn't
actually usable. There's one more step needed before partitioning and
formatting the drive in this way. In that Disk Utility dialogue box,
you need to click the Options
You'll see that the disk is still set to use a DOS-style Master Boot
Record. Change that setting to GUID
(for Intel-based Macs). Click OK to return to the main dialogue box
window. Now you can apply the settings to create a Mac OS Extended
Now you can connect the disk to an AirPort Extreme's
USB port - or if you want to share both a hard drive (or hard drives)
and a printer using the base station's single USB port, you can use a
USB hub to connect multiple USB devices. But your AirPort Extreme needs
to be told to actually share the connected disk.
|2. Tell Your
Base Station About the Drive
now need to use the AirPort Utility on a Mac to reconfigure your
AirPort Extreme. Like the Disk Utility, you'll find it in your Mac's
Applications > Utilities folder. When it opens, it should show you
your AirPort Extreme in the left column. Click the Manual Setup button
on the bottom of the window, then (after a moment), click on the Disks
icon on the top.
You should see your connected disk listed, complete with whatever name
you gave it in Disk Utility. Click on the File Sharing tab.
need to enable file sharing. Note the various password options; I chose
to use the same password that I use to connect to the AirPort Extreme.
There is also an option to connect over the Internet, which I haven't
experimented with, and to enable Windows File Sharing by entering a
Windows workgroup name.
After making your changes, click the
Update button. Note that your AirPort Extreme will restart, dropping
any Internet or other connections for a few moments.
this point, your AirDisk can be accessed from computers connecting to
your AirPort Extreme. In the Finder, for instance, clicking on the
Shared item in the sidebar, I see an All item; clicking on it, shows me
that my iMac has a shared drive, as does my AirPort (named 'kamloops'
in the screen capture image); clicking on that icon lets me connect to
the shared FreeAgent drive.
I want to do more - I want to be able to use Time Machine to back up my
Macs to this drive. And again, it's not quite as simple as just opening
the Time Machine preference.
3. Make It Work with
though the drive is being shared by my AirPort Extreme, I didn't see it
in Time Machine's list of available disks. (To get that, open System
Preferences and click on the Time
Machine icon, or if you have a little Time Machine icon on the
top menu bar, you can click it then select Open Time Machine Preferences from
the dropdown menu).
To make that drive appear in the Time Machine
list, I first needed to go to the Finder and Connect
to the shared drive so it will appear as an icon on the desktop. It
will have a blue drive icon with the same wireless logo that Apple uses
for its AirPort settings on the menu bar and other places.
Your shared drive should now appear in the Time Machine preferences Choose Disk list.
here on, it's straightforward: You can select the shared disk, setting
it for use for Time Machine backups. Note that Time Machine defaults to
backing up every hour - I like the free TimeMachineEditor
(see Free Time Machine Editor Does One Thing and Does It
Well) to change that; in my case, I've set it to backup daily.
I needed to have the shared disk's icon on my desktop in order to
select it in the Time Machine preference, Time Machine will happily
continue to use that disk from then on, whether the icon is mounted on
the desktop or not. While it is backing up, you'll temporarily see a
white backup drive icon on the Desktop.
- the first backup is going to take some time.
When using an AirDisk with Time Machine, you should be aware of several
with other Time Machine backups, if you have virtual OS software like
Parallels Desktop, VMWare Fusion, or Virtual Box installed, you may
want to exclude your virtual drives from the Time Machine backups -
otherwise, every time you run the virtual systems, Time Machine will
want to back up the entire multi-gigabyte files, since they've changed
- even though the changes may be trivial.
up over a WiFi network is significantly slower than backing up to a
disk that's physically connected, or even to a disk that's accessed
across a wired ethernet network. For its first backup, my MacBook had a
bit over a million files to backup, totaling 136 GB. I started at about
5 p.m. one evening; the backup finished the middle of the following
morning, averaging about 8.5 GB per hour. Luckily, most subsequent
backups deal with far fewer files and will only take a few moments.
- As I described in my earlier article about using Time Machine with a shared drive,
Time Machine creates a compressed "sparse bundle" file that contains
all its backups. This is unlike what you'll see if you use Time Machine
to backup to a drive physically connected to your Mac - in that case,
you'll see individual folders for each recent backup with more easily
accessible copies of the backed up files.
of this, if you need to make use of your backup in case of an emergency
(or purchase of a new Mac), you may have to again be patient - if you
try to speed up the restore by physically connecting the backup drive
to your Mac, I suspect you won't be able to access the backup . . . the
restore may need to be done the same way it was created - across the
network, slowly. (Please let me know if I'm wrong about this. I would
much prefer the speed and convenience of being able to restore with the
drive physically connected).
Despite the speed issues, I
find the convenience of having a large amount of inexpensive storage
available to multiple computers makes using an AirDisk worthwhile.