[Discuss] Home backup disks: USB vs NAS

[Doug]

I was looking into setting up a time machine backup disk for the macs
in the house. There appear to be hundreds of USB2.0 external devices
which transfer at a rate of ...

USB 1.0 2mbps
USB 2.0 Full Speed 12mbps
USB 2.0 High Speed 480mbps
USB 3.0 5 gbps

I am seeing USB 2.0 all over the place, but few references to Full
versus High Speed. I don't know how common one is versus the other.

If one wants the ethernet port, the device becomes a Network Attached
Storage (NAS). I have 100base-T Ethernet in the house, along with
802.11n. Those should provide 100mbps connections to a NAS.

Western Digital My Book Live sells a 1TB for $130 or 2TB for $150. I
would think that when you wanted to get something off these disks, NAS
might make a significant difference if it is 12 versus 100, unless one
has the High Speed USB which would win in that case (unless the disk
is limiting somewhere in this range).

One thing that bothers me about either setup is having these things on
all the time. Does anyone sell a device that wakes up when needed?

If you had the choice between a USB backup or NAS at home, which would
you prefer? Should I even worry about the speed differences for this one
kind of task?

Doug