[Discuss] Home backup disks: USB vs NAS

[blu at nedharvey.com (Edward Ned Harvey)]

> From: discuss-bounces at blu.org [mailto:discuss-bounces at blu.org] On Behalf
> Of Doug
> 
> USB 1.0 2mbps
> USB 2.0 Full Speed 12mbps
> USB 2.0 High Speed 480mbps
> USB 3.0 5 gbps

You're not talking about a USB fob, are you?  They normally don't put that
kind of information on usb hard drives, because usb hard drives are all the
same.  They're USB 2.  Maybe some USB3 are starting to hit the market now,
but it doesn't matter, cuz a single hard drive isn't going to significantly
outperform the usb2 bus anyway.

Pretty much any usb hard drive will be fine.  As long as it's a hard drive,
and not a usb fob.  

Be aware, for time machine, you want to use the whole disk for time machine
only.  Because time machine will grow to consume the whole disk, it makes
the disk unuseful for other purposes.  (Unless you partition it.)


> 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.

You can't run time machine to just any old nas device.  It has to support
time machine.  There are a bunch that do - but not your typical WD MyBook
and so on.

If you want to run across the network, you should either become an expert at
running time machine, or just buy the apple time capsule.


> 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).

No matter which thing you choose, you will not care about the speed of time
machine.  It's so fast, and silent in the background, that it simply won't
matter how fast or slow it is.  

Even if you run over the wifi, which is just about the slowest thing you
could possibly do, it will be fine.  (Note: On a 54Mbit wifi network, with
noise isolation and wiring antennas directly together for a perfect
connection and only a single device talking to a single device ... You can
get at best a theoretical 26Mbit actual payload.  In reality it's much lower
because you have distance and noise and blah blah blah.)


> 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?

Supposing there is some place in your house, where you regularly put the
laptop down and let it charge.  You could have the usb hard drive sitting
there too.  Assuming it's a 2.5" hard drive that gets its power from the USB
port, or better yet, the firewire port, then obviously it will not be on as
long as you don't have it connected.

BTW, why would I say firewire is better?  Not because of speed.  Because of
power.  On the USB, it cannot provide enough power to *reliably* power the
hard drive.  So you have to get a drive with a Y-split cable and plug it
into 2 usb ports, and those are all of your USB ports.  So long, external
mouse & keyboard & everything else!  But nothing anywhere uses firewire.
;-)   And firewire carries oodles of power.  So it just plain works better,
when we're talking about external hard drive & time machine.


> 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?

Personally I do the nas thing.  Because I like to be a time machine expert,
and I'm going to keep it on for other reasons anyway, and even if I weren't
- You should do a power calculation.  You'll see that a 30W-40W time capsule
is insignificant in terms of power draw.