Prev: Industrial-Grade CF Memory
Next: Cloning SATA Drives?
From: DJW on 17 Mar 2010 11:45
First question can a firewire 4 pin outlet or cord transfer data at
800 Mbps ever?
I know it is also dependant on the external devise whether it can
achieve 800 mbps rates but can 6 pin devices transfer at 800 Mbps? Or
does the connection have to have a 9 pin at each end and a 9-pin cord
for external hookup?

Also why do some internal PCI (PCI-E) boards have an optional 12V
internal connector for power from PC power supply? Is that when a
large number of external devises are being all hooked up to the
firewire buss?

And is firewire 400 about the same speed as USB 2.0 so if I have a DVD
burner or external ATA hard drive attached to one or the other is data
transfer going to take about the same amount of time?
From: Rod Speed on 17 Mar 2010 13:15
DJW wrote:

> First question can a firewire 4 pin outlet or cord transfer data at 800 Mbps ever?

Yes.

> I know it is also dependant on the external devise whether it can
> achieve 800 mbps rates but can 6 pin devices transfer at 800 Mbps?

Yes.

> Or does the connection have to have a 9 pin at each end and a 9-pin cord for external hookup?

Nope.

> Also why do some internal PCI (PCI-E) boards have an optional
> 12V internal connector for power from PC power supply?

Because the PCI-E card edge connector doesnt
always provide enough power in all motherboards.

> Is that when a large number of external devises
> are being all hooked up to the firewire buss?

It isnt just a large number of external devices.

> And is firewire 400 about the same speed as USB 2.0

That question is a bit complicated because the firewire protocol
is quite a bit simpler, so thruput can be higher in the real world.

> so if I have a DVD burner or external ATA hard drive attached to one or
> the other is data transfer going to take about the same amount of time?

With the DVD burner the time is normally determined by the
burn time, not the time to transfer over the electrical connection.

With a hard drive, firewire can be faster, but eSATA etc is faster again.


From: Yousuf Khan on 18 Mar 2010 11:23
DJW wrote:
> And is firewire 400 about the same speed as USB 2.0 so if I have a DVD
> burner or external ATA hard drive attached to one or the other is data
> transfer going to take about the same amount of time?

USB 2.0 is 480 Mbits/s vs. FW-400 being 400 Mbits/s. In theory, USB 2.0
is slightly faster, however most people consider FW to be still faster
in practical terms, since it has lower overhead than USB.

However, for a DVD burner, I think either USB 2.0 or FW-400 interface
speeds are faster than the internal disk transfer speeds, so there
should be no difference there. Then your next question would be not
which is faster, but which one works with less CPU overhead. I don't
have any idea whether there is a difference between either one for CPU
overhead.

On the other hand, I *have* tested Firewire, USB, and eSATA for hard
drive applications. A friend of mine has a WD MyBook external drive with
all three interfaces on it, and we were able to test all of them a
couple of years back. The Firewire was even 800 Mbits/s in this case.
Despite that, we found that the USB beat the FW-800 in performance on
the same disk and same machine. It wasn't a huge margin, but noticeable.
And eSATA left them both in the smoke. The drive attached via eSATA was
just as fast as the internal hard disks. eSATA has the same speed limits
as internal SATA, at 3000 Mbits/s, so obviously it's a huge difference.

However, on the MyBook we found that obtaining proper SMART data was
only available when using USB, not FW or eSATA. This was a little weird
since eSATA is supposed to be closest to bare-metal, direct to hard
drive with no middle-men. Usually if you ever expect to be able to read
SMART data about the hard disk, then you have to use something like
eSATA. But the MyBook employs some sort of a simple RAID chipset
internally on its eSATA interface (even though it's not a RAID enclosure
and it's just a single drive), and it abstracts the SMART data away from
being read on the machine. However, it passes the SMART data through the
USB interface, but not the FW, or the aforementioned eSATA. These days
USB chipsets are implementing SMART pass-through more and more, but I
don't think Firewire ones are. So it was decided it was better to be
able to monitor the drive through SMART rather than having the speed of
eSATA, and FW was neither fast enough or able to pass SMART, so USB was
chosen as the final interface.

Yousuf Khan
From: Arno on 18 Mar 2010 21:49
DJW <ddwr(a)hotmail.com> wrote:
[...]
> Also why do some internal PCI (PCI-E) boards have an optional 12V
> internal connector for power from PC power supply? Is that when a
> large number of external devises are being all hooked up to the
> firewire buss?

Firewire can supply far more power than USB over the bus.
One number I found was up to 45W (USB has a maximum of 2.5W).
This exceeds what you are allowed to draw from a normal
PIC/PCI-E slot, hence the connector.

Arno

--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
 | 
Pages: 1
Prev: Industrial-Grade CF Memory
Next: Cloning SATA Drives?