New MBP: FW daisy chaining?

[Empr]

Hi, I was going to get a new MBP, I'm thinking the low end 15 inch, and I will want to run Logic on it. Do you think this MBP would be a good choice?

One concern I have is that there is only 1 FW port and no express card. I was planning on getting a FW interface and external HD. I know I can daisy chain FW, but do you think this will effect the performance I am getting from my external devices?

 

[spinnerlys]

If you have a FW800 HDD and a FW400 audio interface and daisy chain them, you will only get FW400 speeds from the FW800 HDD, as the lowest FW device in the chain determines the maximum FW speed.

I don't know if it's a good choice, but depending on the complexity of your Logic projects an external monitor might come in handy.

 

[Empr]

Thanks, that is good to know. Would a hub work better, or are there any other setups that might work as well as a FW400 interface and FW800 HDD?

 

[spinnerlys]

Working with a FW400 audio interface will only give you a maximum of 40MB/s of data throughput, so having a separate FW800 device (HDD as a scratch disk for example) on a separate FW800 bus will not help much when working with the FW400 audio interface, as it can only process as much data as FW400 allows.

So just daisy chaining will suffice your needs, as even a FW hub is not a bus multiplier but a simple port multiplier, that works like daisy chaining FW devices.

 

[Empr]

Interesting... my friend uses a USB interface and a FW external hard drive. Are you saying that he would be getting the same performance if he used a USB drive since the USB interface is negating any FW HDD benefits?

Also, are there any decent FW800 interfaces around? All the ones I've seen are FW400.

 

[spinnerlys]

It always comes down to the lowest common denominator, for example you have a device that works with USB speeds (25-35MB/s, not constant, CPU hogging) and a device that works with FW800 speeds (55-65MB/s, constant, not CPU hogging because of dedicated FW chipset) and both work together, you will only get USB speeds out of that arrangement.

Is that clear enough?

 

[Rodent]

Working with a FW400 audio interface will only give you a maximum of 40MB/s of data throughput, so having a separate FW800 device (HDD as a scratch disk for example) on a separate FW800 bus will not help much when working with the FW400 audio interface, as it can only process as much data as FW400 allows.

So just daisy chaining will suffice your needs, as even a FW hub is not a bus multiplier but a simple port multiplier, that works like daisy chaining FW devices.

What if an expresscard FW adapter is used? Will running a FW400 AI off the built-in FW800 port while running FW800 HD off the expresscard FW800 port result in the HD's only running at FW400 speed as well?

Also, what if the FW400 device is daisychained to the end of the FW800 chain? Would the HD not get FW800 speed in a fashion like this: Comp = HD - AI

 

[Empr]

Good question.
Also it seems strange that my friend's music course would have told him to get a FW drive if he was only able to run it at USB speeds due to his interface.