Re: Time Machine & Laptops.

In article <uce-F8EE99.09063009102008@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Gregory Weston <uce@xxxxxxxxxx> wrote:

In article <jollyroger-A091E8.17575208102008@xxxxxxxxxxxxxxxxxxx>,
Jolly Roger <jollyroger@xxxxxxxxx> wrote:

In article <uce-7EF0FB.18335908102008@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Gregory Weston <uce@xxxxxxxxxx> wrote:

Portable USB-powered drives are an abomination. Even for a 2.5"
mechanism, the bus is not required to supply enough power to get the
drive going. As a result, most of them don't work reliably on Macs.

Hmm... that's a very misleading statement.

I use a Seagate USB 2.5" drive all the time and it works great. The
catch is you need to use the USB cable *that came with the drive*.
Often
these drives come with USB cables that split off into a Y and take up
two USB ports on the computer so the drive gets enough power. I've
tried
using a normal (single) USB cable with the drive, and while it does
spin
up, it isn't able to seek properly, and fails to mount as a result. The
bottom line is if you can live with two ports being taken up while the
drive is connected, you're golden.

The Y cable (greatly) increases the chance of success but still doesn't
guarantee it.

Sorry, but with no evidence to back that up, I'm caling bull***.

That was further down in the same post. At most from 2 USB ports you're
going to get 1A, some of which might already be committed to other
devices depending on the model and configuration of your machine. It's
possible even with 2 physical ports that at any given time there won't
be enough current for the drive.

I haven't seen anything indicating 1 amp is required. And you haven't
stated what the minimum draw might be. It seems to me without knowing
both of those, you can't really make the statement that two USB ports
might not provide enough power.

Unfortunately, I don't have the printed specifications with me at the
moment, and Seagate's web site isn't very helpful either.

Citations would help your case. I have yet to have this drive fail when
using the supplied USB Y cable.

What kind of machine are you on?

A MacBook Pro (Late 2006):

<http://support.apple.com/kb/SP24>

At most you can get an amp, and other devices (like, say,
a built-in iSight) might be using some of that.

You're going to have to show me where it says this drive needs an amp or
more.

Or that you can't rely on having the full 1A available.

So what? I would think it's probable the full 1 amp isn't required,
because this drive has never failed while plugged into two USB ports.

Your last
sentence completely missed the implication of the statement to which it
was nominally a response.

If you say so.

I should point out that I didn't say anything about any specific drive.
I spoke about them as a class. Obviously it's possible that individual
devices may have widely varying startup power requirements.

Then I'm not sure what your point is. You said you wouldn't use such a
drive for backups because they don't work reliably. Respectfully, I
disagree. I've had the opposite experience - they *do* work reliably.

You indicated the reason they don't work reliably is due to power
shortage. I have not experienced that with the supplied cable, and see
no evidence stating the maximum power output of a amp is required.

I'm not sure where to go from here.

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