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General discussion

What is 'daisy chain' in hard drives?

by yashgta Oct 16, 2007 4:33AM PDT

I am about to purchase a lacie D2 extreme quad 500 gb hard drive, (simply because it fits perfectly in my budget and needs(firewire 800). And I read that it has daisy chain capability. I am very unsure to what kind of things I can do with that. I understand simply that I will be able to plug in another hard drive to the second firewire 800 port on the hard drive and access it on my macbook pro, but will the speed suffer? I mean will the performance of both the hard drives go down substantially? or only the second harddrive will be slower? also, can I attach a usb ipod to the port on the hard drive if my laptop ports are full/occupied? thanks for the help. Happy

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3 Posts
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Daisy Chain
by mrmacfixit Forum moderator Oct 16, 2007 5:56AM PDT

Your definition is correct.
Firewire from your computer to one of the ports on the back of the external drive, Firewire from the second port to the next external, and so on until you reach the limit. that would be 63!

There will be no slowdown of data as the data does not travel through each device, just through the interface.

No, you cannot plug your iPod into the USB port on the back of the external, if it is connected to your computer via firewire. There would be no USB connectivity back to the computer.

P

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800mbps x 63?
by yashgta Oct 16, 2007 8:46PM PDT

But I'm sure that since the firewire 800 on my computer can't go above 800 mbps, if I connect 63 or for that matter two hard drives, my computer would still only be able to use 800mbps and not 63 times 800 or 1600. right? so if the other hard drive is firewire 400 compatible, I'd be better off plugging it in directly to my computer's firewire 400 port, correct?

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The number of Firewire devices
by mrmacfixit Forum moderator Oct 16, 2007 9:48PM PDT

on a single chain doesn't have a lot to do with the speed of Firewire connection.

I did not say that you would get 63 (the maximum number of firewire devices connection on one chain) times 400/800.

You will still only be able to pull a maximum of 400/800 from the chain at any one time.

You ability to mix 400 and 800 together depends on the design of the 800 interface. If it has 800 and 400 connections on the rear, you should be able to connect the 400 device to the 800 and the 800 to the Mac.

You really do not gain anything by plugging the 400 into the 400 port and the 800 into the 800 port unless you plan on pulling data from both drives at the same time. On the other hand, you probably do not lose anything either.

Once again, the max speed of your chain is not dictated by the number of devices connected to it.

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