Machine Can Now Backup to a Shared Hard Drive
by Alan Zisman (c)
published in Low
2008.07.08 Zis Mac column
released the Time Machine backup utility as part of Mac OS X 10.5
"Leopard" in October 2007. Time Machine is most commonly used to back
up to an external USB or FireWire hard drive directly attached to a Mac
March 2008 updates (to both Time Machine and
AirPort) allowed Leopard users to use Time Machine to backup to USB
hard drives connected to one of Apple's AirPort Extreme base stations.
As well, Apple has released a pair of Time Capsule models - effectively
a single device combining an AirPort 802.11n base station with either a
500 GB or 1 TB hard drive.
I've got two Macs at home - a 17"
iMac and a 12" G4 PowerBook notebook. There's a 500 GB USB hard drive
plugged into the iMac, which has been set for regular Time Machine
backups. I was able to use these backups to rescue myself from a
self-induced computer crash (see Restoring a Crashed Mac with an Install Disc and Time
even though I've been using the PowerBook far more often than the iMac
lately, I had no backup strategy for it. Oh, I could have unplugged the
external drive from the iMac, plugged it into the PowerBook, and run
Time Machine or some other backup software, and then reconnected the
drive to the iMac. But I never seemed to get around to doing that.
setting the Time Machine drive as shared on the iMac, I could view its
contents from the PowerBook, but I couldn't set it as the target disk
for that system's Time Machine.
It's not clear to me whether
what I wanted to do - back up to an external drive shared by another
Mac running Leopard - was part of Apple's plan for Time Machine or not.
In fact, it seems like even Apple isn't clear. Apple's discussion
of Time Machine as one of Leopard's features states: "Time Machine can
also back up to another Mac running Leopard with Personal File Sharing,
Leopard Server, or Xsan storage devices."
But an Apple online support page, Mac OS X
10.5: Where Can Time Machine Back Up?
(dated June 10, 2008), says:
Machine backs up to either an external disk (such as a USB 2.0 or
FireWire-based third-party drive), a secondary internal disk or
partition (if your computer supports additional internal drives), or an
available Mac OS X Server version 10.5 volume."
Either Time Machine can back up to a disk attached to another (non-OS X
Server) Mac or it can't. Take your pick.
I remember checking some while ago and not seeming to be able to do it.
somewhere along the road of Apple's updates, that changed. Maybe it was
the OS X 10.5.4 update that I installed on both Macs just a few days
ago. Maybe it happened sometime before that. (Maybe it was always
possible, but I wasn't going about it the right way). But now, as if by
magic, the external backup drive connected to my iMac appears in the
PowerBook's Time Machine list.
shows up as an option as long as I've set it as shared on the iMac and
logged into it on the PowerBook, giving me an icon for it on the
The external drive is connected into a USB
port on the iMac; the iMac has a wired ethernet connection to my
router, while the PowerBook is connecting to the router via 802.11g
WiFi. As a result, access to the backup drive is much slower from the
PowerBook than from the iMac.
I've set the Time Machine options
on the PowerBook to not backup folders containing virtual drives for
emulated Windows (using Virtual PC and Guest PC) and an emulated
classic Mac (using SheepShaver
these large virtual drives change every time they are used, and that
would result in repeated huge incremental backups. That leaves about
22.5 GB of stuff to backup on the PowerBook. (I keep nearly all of my
media files and documents on the iMac.)
up 22+ GB of data over an 802.11g connection took a long time the first
time; I started around 10:15 in the morning, and it finished around
6:30 p.m., 8 hours and 15 minutes later.
After that, Time
Machine only backs up new or changed files. These backups are much
quicker. Interestingly, while I can only configure Time Machine to use
the shared hard drive when it is mounted with an icon on the Desktop,
after ejecting that drive, Time Machine is still able to access it for
The backup process seems a bit different backing up to
this shared drive than on the system that's directly attached to the
drive. While Time Machine is running on the PowerBook, a new virtual
drive icon appears on its Desktop named Backup of Alan Zisman's
PowerBook G4 12". That icon disappears when the backup is finished.
when I look at the contents of my backup drive in the Finder, there are
85 sequential backups of the iMac, listed by date in a folder. While
there are only a few backups for the PowerBook, they all seem to be
contained in a single file, identified as a "sparse disk image bundle";
double-clicking that file mounts it on the PowerBook's Desktop - which
is also what happens if I open the Time Machine utility
the PowerBook is a notebook, it travels with me; when it's not
connected to my home network, it's unable to access the shared drive.
(Maybe setting port forwarding on the router would allow it to be
shared over the Internet, but I'm not sure I want to go there, even if
it is possible.)
Wikipedia's article on Time Machine
last updated on June 10, 2008, states that Time Machine "...does not
support backing up to normal network attached storage devices or
servers." I don't have the ability to test whether it can now back up
to so-called NAS devices - hard drives with built-in ethernet ports,
allowing them to connect directly to a network. (If anyone can check
this out, please let me know - and Apple's Time Capsule devices are not
'normal NAS devices' for the purposes of the Wikipedia article).
for me, and probably for others as well, the ability use Time Machine
to backup multiple Macs on a home or small business network to a single
hard drive connected to one of those Macs is a handy one. If nothing
else, it's more affordable than Apple's Time Capsule devices. In
Canada, Apple sells the 500 GB Time Capsule for C$329 ($529 for the 1
I paid $99 for a standard 500 GB SATA internal hard
drive, popped it into a $39 external drive case. While some might point
out that Apple's Time Capsule also includes the equivalent of Apple's
AirPort wireless router, I already had a wireless router (a $39 D-Link
model). Yes, Time Capsule supports faster 802.11n wireless networking,
but my PowerBook doesn't, so that wouldn't help.
So thank you,
Apple, for letting me back up my multiple Macs to a single, shared
external hard drive - even if your own support pages don't know that
this is possible.
April 2009- reader Melvin was having trouble making this work. He
discovered: "the problem was: backing up doesn't work over AFP.
You have to do it through FTP."
And in September 2009,
reader Nicholas noted: From: http://www.kremalicious.com/2008/06/ubuntu-as-mac-file-server-and-time-machine-volume/:
'Time Machine Full System Restore
case of a full system restore you would have to boot your Mac from the
Mac OS X installation DVD (the one delivered with your Mac) by pressing
the c key during boot. Your Mac will start with a minimal UI where you
have a Utilities section in the top menu bar. There you’ll find
“Restore from a Time Machine Backup” but it won’t find your network
share with your Time Machine backup. Luckily Dmitry Nedospasov found a
way to manage this by simply mounting your Time Machine network share
with the Terminal (which you can find under Utilities in the menu bar
too) by utilizing the following syntax (shamelessly copied from Dmitry):
mount -t afp afp://username:password@hostname/ShareName
everything instead of /Volumes with your matching names. You can test
if your network share was properly mounted by doing
which outputs the content of the Volumes folder and you should see your
you can close the Terminal and select “Restore from Time Machine
Backup” from the Utilities entry in the menu bar and select your
mounted Time Machine backup and thats it. Oh, needless to say: a
gigabit ethernet connection will speed things up dramatically even
compared to (draft)n-WLAN.'