external HDD housings

  • Thread starter Thread starter Lez Pawl
  • Start date Start date
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Lez Pawl

I use the Belkin drive housings, one has only USB in and the other has USB
and 2 x Firewire ports. It was the latter that went wrong, both Firewire
ports went TU.

Why do they fit 2 Firewire ports when I understood you could not connect 2
comps to one drive at any one time.

Looking at a number of manufacturer housings , this seems common practice.
 
Lez Pawl said:
I use the Belkin drive housings, one has only USB in and the other has USB and 2 x
Firewire ports. It was the latter that went wrong, both Firewire ports went TU.
Click to expand...
Why do they fit 2 Firewire ports when I understood you could not connect 2 comps to one
drive at any one time.
Click to expand...

Its for loop thru of more than one external drive, one PC.
Looking at a number of manufacturer housings , this seems common practice.
Click to expand...

Yep, to allow more than one external drive.
 
Lez Pawl said:
OK thanks....
Click to expand...

What I forgot to say is that its pretty common to see just one firewire
port on the PC, but more than one USB connector on the PC, so there
is more need for loopthru with firewire than with firewire.
 
Rod Speed said:
What I forgot to say is that its pretty common to see just one firewire
port on the PC, but more than one USB connector on the PC, so there
is more need for loopthru with firewire than with firewire.
Click to expand...

yes my dell has 3 onboard USB ports and a Belkin pc card adaptor providing
another 2. All these ports are dedicated to external components. The single
firewire was useful to keep the backup drive connected...........I may well
get another Firewire housing as they don't cost much.
 
Lez Pawl said:
I use the Belkin drive housings, one has only USB in and the other has USB
and 2 x Firewire ports. It was the latter that went wrong, both Firewire
ports went TU.

Why do they fit 2 Firewire ports when I understood you could not connect 2
comps to one drive at any one time.

Looking at a number of manufacturer housings , this seems common practice.
Click to expand...

Firewire and USB are designed differently.

USB is connected in a "tree" fashion. One device per port. Of course the one
device can be a hub, splitting to mutliple devices.

Firewire is connected ina "chain" fashion. One device connects to the next,
to the next, to the next, etc. This minimizes the number of connectors you
need on the PC. You shouldn't have need for a hub in a Firewire
installation, but they are available.
 
"Lez Pawl" said:
yes my dell has 3 onboard USB ports and a Belkin pc card adaptor providing
another 2. All these ports are dedicated to external components. The single
firewire was useful to keep the backup drive connected...........I may well
get another Firewire housing as they don't cost much.
Click to expand...

I've actually tried two Firewire housings in series, and the
one furthest from the computer, gets slower service. While
you can daisy chain Firewire drives, it doesn't necessarily
always give you a high performance configuration. And naturally,
there are not going to be a lot of review articles that evaluate
a config like that. (I no longer have the enclosures, so cannot
repeat the experiment.) Shown in this figure, are two Firewire
cables, one cable computer-to-drive, the other drive-to-drive.

Computer ------- --------- x
1394 | | | |
port | | | |
-------- ---------
Disk1 Disk2
~30MB/sec ~20MB/sec

HTH,
Paul
 
I've actually tried two Firewire housings in series, and the
one furthest from the computer, gets slower service. While
you can daisy chain Firewire drives, it doesn't necessarily
always give you a high performance configuration. And naturally,
there are not going to be a lot of review articles that evaluate
a config like that. (I no longer have the enclosures, so cannot
repeat the experiment.) Shown in this figure, are two Firewire
cables, one cable computer-to-drive, the other drive-to-drive.

Computer ------- --------- x
1394 | | | |
port | | | |
-------- ---------
Disk1 Disk2
~30MB/sec ~20MB/sec
Click to expand...


Were they the same enclosure and drive though or different?
If different, I wonder what would happen if you swapped
their positions around.
 
Were they the same enclosure and drive though or different?
If different, I wonder what would happen if you swapped
their positions around.
Click to expand...

They were the same enclosure brand/model number.

And I may even have tried swapping them around. I don't
remember now.

My suspicion is the bridge board inside the controller,
cannot handle thru-traffic on 1394 at the full rate.
Either that, or Firewire is sensitive to transport
latency. (Whole packet stored in bridge chip, before
being forwarded ?)

In any case, with that enclosure, it made more sense
to connect both enclosures directly to the computer.

Paul
 
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