Copy from external HD to external HD on Firewire 800

[sneyders]

I was just wondering. When you have two external harddisks connected via Firewire 800 to your Mac, and you copy from one disk to the other will the traffic pass via the Mac or will it be from disk to disk?

Practical setup is Powerbook G4 + 2 x LaCie Extreme 300GB Triple interface drives.

I will have this setup in a few days and this came up doing some calculations on maximum throughput when backing up databases.

Thx

 

[dmetzcher]

Not sure I understand the question. Your Mac OS is controlling the copy from one of the drives to the other. I have a similar setup with two LaCie drives, though I'm using the FW400 ports, not the FW800. The OS itself manages this copying of data from one drive to another. It's not like it sends a command to both drives and tells them, "OK, you send this file over to that drive, and you accept the file from that drive", and then they just handle the transaction. The OS knows the two volumes exist, and it knows how to get data onto each of them.

I'm not sure what overhead it adds, if any, really. On my machine, I can copy large amounts of data and I never really notice a slowdown at all, and I'm using a lowly iBook G4. I keep working while the files are moving around in the background.

Was that what you were looking for?

 

[ElDiabloConCaca]

I was just wondering. When you have two external harddisks connected via Firewire 800 to your Mac, and you copy from one disk to the other will the traffic pass via the Mac or will it be from disk to disk?

All data "passes via the Mac", no matter what. Since your processor and front-side bus can pass data many, many, many times faster than a hard drive interface, you will not notice any slowdown and it will be as if the data were simply going from one drive to the other.