Information Technology Reference
Although NAS marketing paints a rosy picture, I urge circumspection
when considering NAS as a backup medium, for several reasons:
Even though the drive functions as its own file server, a NAS device
can't run backup software directly. You must still run a backup
program on each of your network's computers individually. Your
NAS drive may come with free backup software, however.
Some NAS devices can only be formatted using FAT32, a Windows
file system. (The AirPort Extreme Base Station and Time Capsule
don't have this limitation, of course.) Although Mac OS X can read
from and write to FAT32 volumes, some metadata may not be
stored properly. Your backup software may address this limitation
by storing data in a special archive file, but if it backs up files in a
Finder-readable format, you risk losing data.
Many NAS devices don't support Time Machine; and of those that
do, some require a firmware update to work under 10.7 Lion or
later. (And, if you happen to have an older NAS whose firmware will
never be updated, you may simply be out of luck.)
You can't create a bootable duplicate onto a NAS. Because of the
complexities of permissions, links, and other details of Mac OS X's
structure, the only way to create a bootable duplicate over a network
is to back up to a drive connected to a Mac running one of a very few
backup programs specially designed for this purpose. At present,
the only programs I know of that can do this are Carbon Copy
Cloner, ChronoSync, Retrospect, and Synk—and of course none of
these can run on your NAS itself.
Even if you could somehow create a bootable duplicate on a NAS
(for example, storing the data on a disk image), it isn't possible to
boot your Mac directly from a duplicate stored on a NAS device—
even if you have an AirPort Extreme or Time Capsule. You will have
to restore (or re-duplicate) a duplicate to another hard drive first.
Your NAS drive may have a USB port, but USB ports on NAS
devices are usually used only to hook up shared printers or, in some
cases, secondary hard drives.