Slightly OT: Firewire drives - daisy chain or hub?

[D. D. Brierton]

This is perhaps a little off-topic, but maybe not too much so as the
answer might depend on how Linux and FC3 handle Firewire. I need to copy
large (~80GB) amounts of data from one external Firewire/IEEE-1394 hard
disk drive to another. My machine only has one Firewire port. One of the
drives has a Firewire port on the back, so it is possible to daisy chain
the disks together. Alternatively I could go out and buy a fairly
inexpensive powered Firewire hub and connect the two drives to that.

Are there pros and cons to these two methods that I should be aware of?
Is one preferable to the other?

TIA.

Best, Darren

-- 
=====================================================================
D. D. Brierton            darren(a)dzr-web.com          www.dzr-web.com
       Trying is the first step towards failure (Homer Simpson)
=====================================================================

[Tony Nelson]

At 2:26 PM +0100 8/1/05, D. D. Brierton wrote:
> This is perhaps a little off-topic, but maybe not too much so as the
> answer might depend on how Linux and FC3 handle Firewire. I need to copy
> large (~80GB) amounts of data from one external Firewire/IEEE-1394 hard
> disk drive to another. My machine only has one Firewire port. One of the
> drives has a Firewire port on the back, so it is possible to daisy chain
> the disks together. Alternatively I could go out and buy a fairly
> inexpensive powered Firewire hub and connect the two drives to that.
>
> Are there pros and cons to these two methods that I should be aware of?
> Is one preferable to the other? 
Both should work, and should produce the same performance.  All your
Firewire devices are on the same bus so they will see all the data in
either case, and there's only one interface on the computer, so the drives
will have to take turns transferring data.

The main advantage to using a powered hub (from my perspective having done
some Firewire development (on MacOS)) is that when somthing bad happens and
Firewire destroys the Firewire Interface you're hot-plugging something
into, it will be either the device or the hub that is destroyed, not the
computer's motherboard.
____________________________________________________________________
TonyN.:'                       <mailto:[e-mail]>
      '                              <http://www.georgeanelson.com/>

[D. D. Brierton]

On Mon, 2005-08-01 at 11:42 -0400, Tony Nelson wrote:

>  Both should work, and should produce the same performance.  All your
>  Firewire devices are on the same bus so they will see all the data in
>  either case, and there's only one interface on the computer, so the drives
>  will have to take turns transferring data. 
Right, that makes sense.

>  The main advantage to using a powered hub (from my perspective having
> done
>  some Firewire development (on MacOS)) is that when somthing bad happens and
>  Firewire destroys the Firewire Interface you're hot-plugging something
>  into, it will be either the device or the hub that is destroyed, not the
>  computer's motherboard. 
Eeek. I hadn't thought anything so dire could happen from simply
transferring data. I think I'll pop out and buy a hub. Do you have any
recommendations?

Thank you Tony.

Best, Darren

-- 
=====================================================================
D. D. Brierton            darren(a)dzr-web.com          www.dzr-web.com
       Trying is the first step towards failure (Homer Simpson)
=====================================================================

[Tony Nelson]

At 8:06 PM +0100 8/1/05, D. D. Brierton wrote:
> On Mon, 2005-08-01 at 11:42 -0400, Tony Nelson wrote:
>
> > Both should work, and should produce the same performance.  All your
> > Firewire devices are on the same bus so they will see all the data in
> > either case, and there's only one interface on the computer, so the drives
> > will have to take turns transferring data.
>
> Right, that makes sense.
>
> > The main advantage to using a powered hub (from my perspective having done
> > some Firewire development (on MacOS)) is that when somthing bad happens and
> > Firewire destroys the Firewire Interface you're hot-plugging something
> > into, it will be either the device or the hub that is destroyed, not the
> > computer's motherboard.
>
> Eeek. I hadn't thought anything so dire could happen from simply
> transferring data. I think I'll pop out and buy a hub. Do you have any
> recommendations? 
Not from the transfer, but from the hot-plug, or occasionally for no
apparent reason.  The less often you plug, the less likely the problem is.
The more you like Firewire, the more you plug, the more it happens. :(

No specific recommendations.  Just get a powered hub, as you were planning.
____________________________________________________________________
TonyN.:'                       <mailto:[e-mail]>
      '                              <http://www.georgeanelson.com/>

[Kenneth Porter]

--On Monday, August 01, 2005 11:42 AM -0400 Tony Nelson 
<tonynelson(a)georgeanelson.com&gt; wrote:

>  The main advantage to using a powered hub (from my perspective having
> done
>  some Firewire development (on MacOS)) is that when somthing bad happens
>  and Firewire destroys the Firewire Interface you're hot-plugging something
>  into, it will be either the device or the hub that is destroyed, not the
>  computer's motherboard. 
Good reason to use optical, esp. in an industrial environment where you 
can't trust the other vendor to get his grounds right. It's also not 
susceptible to motor noise, so you can run it right next to the motor drive 
lines for the robotic handlers.