How does daisy-chaining of external drives work?

c-t

macrumors newbie
Original poster
Jul 29, 2010
17
0
I have an iMac with one FW800 port and one FW400 port.

I already have a LaCie Rugged drive with one FW800 port and one FW400 port. I have it connected to my iMac's FW800 port.

Now, I want to connect a second external drive to my iMac. I'm thinking about buying WD My Passport Studio with two FW800 ports.

My question is: There are two choices I can take in order to connect those drives to my iMac:
  1. Connect the LaCie to the iMac's FW400 port and connect the new WD to the iMac's FW800 port.
  2. Connect the new WD to the iMac's FW800 port, and daisy-chain the LaCie to the WD's remaining FW800 port.
My question is: Which option should I choose? I guess option 2 would be better, since both are on the FW800 bus. However, since there are two drives on the same bus, doesn't it slow down the entire bus?
 
Nov 28, 2010
22,684
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  1. Connect the LaCie to the iMac's FW400 port and connect the new WD to the iMac's FW800 port.
  2. Connect the new WD to the iMac's FW800 port, and daisy-chain the LaCie to the WD's remaining FW800 port.
My question is: Which option should I choose? I guess option 2 would be better, since both are on the FW800 bus. However, since there are two drives on the same bus, doesn't it slow down the entire bus?
Option 2 will work just fine, I currently have three HDDs connected to my iMac that way, all with FW800 ports and I get FW800 speeds too.
 

c-t

macrumors newbie
Original poster
Jul 29, 2010
17
0
Option 2 will work just fine, I currently have three HDDs connected to my iMac that way, all with FW800 ports and I get FW800 speeds too.
Okay, thanks. What if you're transferring files from all three drives at once to your Mac (or between one another)? Do things slow down?
 
Nov 28, 2010
22,684
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located
Okay, thanks. What if you're transferring files from all three drives at once to your Mac (or between one another)? Do things slow down?
If I copy from three HDDs via one interface (FW800 in this case) to one HDD, I will be limited by the interface and the one HDD, which has to write three streams onto it.
If I copy from on external HDD to another external HDD via FW800, I get FW800 speeds.