Portable ext. HDDs without power AC?

isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
nospam wrote
Rod Speed wrote

I know some people prefer to use portable external
HDDs, with their power AC connection enclosures
or adapters, for reliability and stability.

That's mad. By definition external HDDs are less reliable than
internal drives just because they are easier to drop and knock
over and because they don1t have as good cooling as you can
easily achieve with an internal drive in a decent case.

don't drop them and they're just as reliable.

No, because they are MUCH easier to bump when using them.

only for klutzes.

Bull****. There are plenty who arent klutzes that don't
even realise that there is a spinning disk in an external
hard drive with the heads flying over the surface and
gyroscopic effects.

Although you can feel the gyro effect if you tilt the drive while it's
spinning, what is the effect *inside it* that can cause a problem?

You can end up with a head crash.

Well, yes, but that's nearly the only mechanical
problem an operating disk can have.

That's not right, you can get bearing failure too.

What I'm asking is, what about the gyroscopic
effect *specifically* is it that causes the crash?

The same effect there has always been with moving a drive when its
spinning.

My point exactly:

Nope.

there is nothing at all about the gyroscopic effect
that makes a disk malfunction any more likely.

Have fun explaining why normal desktop drives have
failed when the system is moved with the drives spinning.

And you can get quite high G loads just by letting the drive
down hard as you place it on the desktop when running.

"Lewis" wrote in message
...
Okay, so one time? In band camp? DevilsPGD was
all, like:
-- Mon, 25 Aug 2014 23:55:08 -0700

In the last episode of , Lewis
said:

Okay, so one time? In band camp? DevilsPGD was
all, like:
-- Mon, 25 Aug 2014 22:07:34 -0700

In the last episode of , Lewis
said:

On modern drives? Nothing. It is nearly impossible for a modern disk to
suffer a head crash.

If you drop the whole device, it will generally park the heads and you
won't suffer a head crash, this is true.

However, if the impact happens without a free-fall drop or other
warning
sign, the sensors won't know to park the heads and you can crash the
heads reasonably easily. This can happen if the initial impact is to
the
drive (or case) itself.

Sure, it is possible. It's very unlikely, and rather difficult. I said
"nearly impossible" not "impossible".

How is that difficult? Any sudden impact that doesn't start with a fall
can make it happen. Dropping something on the drive, or on something
that can pass the force to the drive (for example a metal box that is
physically attached to the drive's frame) can do it.

You would have to drop something directly ON the drive,

Yes.

and drives normally do not operate exposed to things falling on them.

External drives do when you have then on the desktop next
to the device.

It would also take a significant impact.

Yes, but it isnt that uncommon to drop things.

Knocking a tower on it's side, for example, will not necessarily trip a
free-fall sensor, nor will a short 1" drop necessarily give the drive
time to react.

How many head crashes have you seen in the last... oh, let's say 15
years? I know exactly how many I've seen in that time: *zero* and I've
dealt with a few hundred drives in that time. Go back 10 more years and
head crashes were rather common, relatively speaking.

But you treat the drives carefully, don’t throw them around when spinning.

You want to argue that it's possible? Go ahead, I never said it wasn't
possible. Does it happen? And how often?

In the last episode of ], isw
said:

Some portable computers include free-fall sensors, which *with the
participation of the computer's OS*, can park the heads, but I don't
think that many bare drives have them, so an external drive won't have
any auto-park protection from a drop off the table top.

There's no reason that the OS need be involved, the drive could shut
down until either the impact or the free-fall event is over, from the OS
this isn't any different than a drive which pauses to attempt a repair
of a particular sector.

But this is an implementation detail, I'm not really sure what modern
drives actually implement (and nor do I really care since my portable
devices are all solid state and I treat my desktops and servers with
appropriate caution)

--
I wouldn't be caught dead with a necrophiliac.

["Followup-To:" header set to comp.sys.mac.hardware.storage.]
On 2014-08-27, DevilsPGD wrote:
In the last episode of ], isw
said:

Some portable computers include free-fall sensors, which *with the
participation of the computer's OS*, can park the heads, but I don't
think that many bare drives have them, so an external drive won't have
any auto-park protection from a drop off the table top.

There's no reason that the OS need be involved, the drive could shut
down until either the impact or the free-fall event is over, from the OS
this isn't any different than a drive which pauses to attempt a repair
of a particular sector.

That's assuming the sensor is built into the hard drive itself. Not all
hard drives have such sensors. Without such a sensor, the drive is
effectively blind to the tragedy that is about to happen, and therefore
can't react. That's where Apple's sudden motion sensor comes into play:

http://support.apple.com/kb/HT1935

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JR

In article ,
"Rod Speed" wrote:

isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
nospam wrote
Rod Speed wrote

I know some people prefer to use portable external
HDDs, with their power AC connection enclosures
or adapters, for reliability and stability.

That's mad. By definition external HDDs are less reliable than
internal drives just because they are easier to drop and knock
over and because they don1t have as good cooling as you can
easily achieve with an internal drive in a decent case.

don't drop them and they're just as reliable.

No, because they are MUCH easier to bump when using them.

only for klutzes.

Bull****. There are plenty who arent klutzes that don't
even realise that there is a spinning disk in an external
hard drive with the heads flying over the surface and
gyroscopic effects.

Although you can feel the gyro effect if you tilt the drive while it's
spinning, what is the effect *inside it* that can cause a problem?

You can end up with a head crash.

Well, yes, but that's nearly the only mechanical
problem an operating disk can have.

That's not right, you can get bearing failure too.

What I'm asking is, what about the gyroscopic
effect *specifically* is it that causes the crash?

The same effect there has always been with moving a drive when its
spinning.

My point exactly:

Nope.

there is nothing at all about the gyroscopic effect
that makes a disk malfunction any more likely.

Have fun explaining why normal desktop drives have
failed when the system is moved with the drives spinning.

And you can get quite high G loads just by letting the drive
down hard as you place it on the desktop when running.

Correlation is not causation. Clearly, just about the only time a modern
disk can have a head crash is when the head is flying above the disk,
and the only time it is doing that is when the platter is rotating.

But the issue we're discussing is the gyroscopic behavior of the
spinning platter. Can you make a case that it is *specifically* the
gyroscopic effect that causes the crash? I cannot think of any reason
why it would.

Isaac

In article ,
"Rod Speed" wrote:

isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
nospam wrote
Rod Speed wrote

I remember using an external DVD-ROM drive that
used two USB connections that didn't use power AC.

that's a gross hack.

Its no different to using an external wall
wart, much more convenient to use.

it's completely different.

Bull****.

nobody would think of plugging an appliance
into two outlets to get 30 amps instead of 15.

USB is different, stupid.

Actually, no.

Fraid so.

Using a pair of USB ports *on the same device* is a perfectly
legitimate way to get more current than one port will deliver.

Sure, but is nothing like plugging an appliance
into two outlets to geet 30 amps instead of 15.

And as I said, I've done that and it works just fine.

You haven't, actually. There are no appliances that
need 30 amps that plug into a normal outlet that
wont work when plugged into just one and do
work when plugged into two at the same time.

Not ones you buy in a store. Do you ever build things for yourself? I do.

Yep, been doing that since before you were even born,
and built and wired my entire house as well, and powered
the entire house from the builder's temporary supply for
quite a while until the supply authority eventually chucked
a wobbly and demanded I connect the house properly.

Currents just add.

Fraid not.

well, Herr Kirchhoff sure thought so in about
1845, and every electrical engineer since his
time has depended on it being true,

Not in the that situation where you have an appliance
that is plugged into two outlets at the same time.

but YMMV ...

If you have an ammeter, you could try it using the USB ports
on your computer. If you did, I'm fraid you'd be surprised.

I didn1t say it isnt true with the USB ports, it clearly is.

I was talking about your other appliance claim where it isnt.
You don1t see the appliance taking 15 amps when plugged
into one outlet and 30 amps when plugged into two outlets.
It takes the same total current in both situations, because the
current taken is determined by V=IR.

It's pretty clear that the item drawing current has to be able to
draw more than 15 Amps for the two-outlet trick to be of any use.

And there arent any appliances like that.

IOW, you need to have a load that would
draw more than 15 Amps. at local line voltage.

And there arent any appliances like that.

In fact, what I built that worked that way was a portable light board
for in-the-round theater productions. 15 Amps couldn't handle enough
lights, but 30 Amps (from two outlets on different breakers) could.

That's not an appliance.

Its different with USB when the USB port is current limited.

If a USB port's source ability is limited to, say, 0.5 Amps, then
combining two of them you can get pretty close to a full amp
(depends on how well the two hook-ups are balanced).

Yes, but the mains doesn¹t work like that.

OK, I'll bite. In precisely what way is "the mains" different from every
other sort of electrical circuit that makes your claim correct (i.e.
that you can't draw more current from two *independently fused* circuits
than you can get from a single one)?

Isaac

In the last episode of ], isw
said:

In article ,
"Rod Speed" wrote:

isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
isw wrote
Rod Speed wrote
nospam wrote
Rod Speed wrote

I remember using an external DVD-ROM drive that
used two USB connections that didn't use power AC.

that's a gross hack.

Its no different to using an external wall
wart, much more convenient to use.

it's completely different.

Bull****.

nobody would think of plugging an appliance
into two outlets to get 30 amps instead of 15.

USB is different, stupid.

Actually, no.

Fraid so.

Using a pair of USB ports *on the same device* is a perfectly
legitimate way to get more current than one port will deliver.

Sure, but is nothing like plugging an appliance
into two outlets to geet 30 amps instead of 15.

And as I said, I've done that and it works just fine.

You haven't, actually. There are no appliances that
need 30 amps that plug into a normal outlet that
wont work when plugged into just one and do
work when plugged into two at the same time.

Not ones you buy in a store. Do you ever build things for yourself? I do.

Yep, been doing that since before you were even born,
and built and wired my entire house as well, and powered
the entire house from the builder's temporary supply for
quite a while until the supply authority eventually chucked
a wobbly and demanded I connect the house properly.

Currents just add.

Fraid not.

well, Herr Kirchhoff sure thought so in about
1845, and every electrical engineer since his
time has depended on it being true,

Not in the that situation where you have an appliance
that is plugged into two outlets at the same time.

but YMMV ...

If you have an ammeter, you could try it using the USB ports
on your computer. If you did, I'm fraid you'd be surprised.

I didn1t say it isnt true with the USB ports, it clearly is.

I was talking about your other appliance claim where it isnt.
You don1t see the appliance taking 15 amps when plugged
into one outlet and 30 amps when plugged into two outlets.
It takes the same total current in both situations, because the
current taken is determined by V=IR.

It's pretty clear that the item drawing current has to be able to
draw more than 15 Amps for the two-outlet trick to be of any use.

And there arent any appliances like that.

IOW, you need to have a load that would
draw more than 15 Amps. at local line voltage.

And there arent any appliances like that.

In fact, what I built that worked that way was a portable light board
for in-the-round theater productions. 15 Amps couldn't handle enough
lights, but 30 Amps (from two outlets on different breakers) could.

That's not an appliance.

Its different with USB when the USB port is current limited.

If a USB port's source ability is limited to, say, 0.5 Amps, then
combining two of them you can get pretty close to a full amp
(depends on how well the two hook-ups are balanced).

Yes, but the mains doesn¹t work like that.

OK, I'll bite. In precisely what way is "the mains" different from every
other sort of electrical circuit that makes your claim correct (i.e.
that you can't draw more current from two *independently fused* circuits
than you can get from a single one)?

And (to the previous poster), consider in your answer that we do have
appliances almost like this: Dryers and stoves in North America
typically (although not exclusively) use a 240V 30A circuit which is
actually two 120V 15A circuits (in a split-phase configuration).

In defense of how "the mains" is different, there actually is a
difference: AC vs DC current. With AC current you have to consider what
happens if your sources are in phase or not, as it's possible for
different circuits to be 180 degrees out of phase, or on completely
different cycles (when a set of UPSes or generators may kick in)

DC is much simpler in this respect, giving use simple USB circuits that
draw from multiple ports without requiring explicit design on the part
of the supply, or complicated transformer designs on the appliance.

But ultimately, at it's most basic level, North American 240V appliances
are quite similar in concept (if not in design) as they use two
independently fused circuits -- Oh yeah, and the circuit breakers are
usually linked so that tripping one trips the other. Since this is done
mechanically and not electrically, they're still independent fuses from
an electrical standpoint.

--
What's the difference between ignorance and apathy?
I don't know and I don't care.

In the last episode of , Jolly Roger
said:

["Followup-To:" header set to comp.sys.mac.hardware.storage.]

[Fixed that]


On 2014-08-27, DevilsPGD wrote:

In the last episode of ], isw
said:

There's no reason that the OS need be involved, the drive could shut
down until either the impact or the free-fall event is over, from the OS
this isn't any different than a drive which pauses to attempt a repair
of a particular sector.

That's assuming the sensor is built into the hard drive itself. Not all
hard drives have such sensors. Without such a sensor, the drive is
effectively blind to the tragedy that is about to happen, and therefore
can't react. That's where Apple's sudden motion sensor comes into play:

http://support.apple.com/kb/HT1935

Sure. But making the drive itself aware is a better solution since it
doesn't rely upon the computer to have particular hardware, the OS to be
functioning and the driver installed, whereas a solution built into the
drive will work all the time, every time.

Still, for most practical purposes, the difference is probably
interchangeable, at least until you initiate hibernate or shutdown, pick
up your laptop to walk off and drop it in those few moments between when
sensor driver unloads and when the drive itself shuts down.
Unfortunately this is a fairly likely time to drop a laptop, since it's
a likely time for you to be moving it.

The right implementation could, of course, ensure that this driver isn't
unloaded until the drive is powered down, but this would require a
kernel level implementation, and again, is OS specific whereas
implementing it in the drive will work regardless of the OS the user
chooses to use.

--
What's the difference between ignorance and apathy?
I don't know and I don't care.

On 8/26/2014 1:18 PM PT, VanguardLH typed:
So after all the suggestions in the other responses that are based on
unknown hardware, what port types are actually available in your present
computer? Or was this just an curiosity inquiry to possibly affect on
what you might include in a later build?

It was just a curiosity inquiry for the future of portable HDD
purchases. I really like the tiny portable HDDs that don't need the
annoying power bricks and its cable, but I read that they had power
problems. Big enclosures can have extra goodies like ESATA, Firewire,
Thunderbolt, better cooling, etc. So I was wondering if enclosures
existed like that.
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On 2014-08-27, DevilsPGD wrote:
In the last episode of , Jolly Roger
said:

On 2014-08-27, DevilsPGD wrote:

In the last episode of ], isw
said:

There's no reason that the OS need be involved, the drive could shut
down until either the impact or the free-fall event is over, from the OS
this isn't any different than a drive which pauses to attempt a repair
of a particular sector.

That's assuming the sensor is built into the hard drive itself. Not all
hard drives have such sensors. Without such a sensor, the drive is
effectively blind to the tragedy that is about to happen, and therefore
can't react. That's where Apple's sudden motion sensor comes into play:

http://support.apple.com/kb/HT1935

Sure. But making the drive itself aware is a better solution since it
doesn't rely upon the computer to have particular hardware, the OS to be
functioning and the driver installed, whereas a solution built into the
drive will work all the time, every time.

That doesn't change the fact that most drives have no such hardware
built-in, probably to reduce costs. Those who want a drive that has it
built in, then go find and probably pay more for one.

--
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR