iMac Firewire 800 speed question

[JYork23]

I'm looking at heading out to the Apple Store this coming week to pick up an iMac i7. My only concern is with the single Firewire 800 connection in the back.

Does anyone know if I plug hard drive #1 into the iMac with an 800 connection and then daisy chain hard drive #2 with a 400 connection from #1, do I slow down the transfer of the whole chain or just reads/writes from HD2?

 

[Transporteur]

The hole chain will be used in FW400 mode.

 

[gr8tfly]

The hole chain will be used in FW400 mode.

Not true. If the first device is FW800, and you daisy chain FW400 off it, the first device will still operate at FW800 speeds. I've measured it several times on my configuration to confirm this.

Configuration: 3 FW800 > 2 FW400 > 1 FW400 burner.

Tests on a ~800MB DMG file (the 10.5.7 combo updater) to/from internal 320GB 7200RPM (WD Scorpio Black) (just using Activity Monitor for measurement):

Seagate FreeAgent Desk Mac FW800 1TB(first in chain)
read: 68MB/s
write: 68MB/s

Seagate FreeAgent Pro FW400 750GB(about 3rd in chain, after two other FW800s)
read: 36MB/s
write: 36MB/s
​

17" MBP Unibody Early 2009; 320GB WD 7200RPM Scorpio Black; 8GB RAM

 

[Transporteur]

Not true. If the first device is FW800, and you daisy chain FW400 off it, the first device will still operate at FW800 speeds. I've measured it several times on my configuration to confirm this.

Nice to know. Seems as if that depends on the specific drives that are use, since I experienced that my complete chain is limited to FW400 speed as soon as I switched on the FW400 device.

 

[gr8tfly]

Nice to know. Seems as if that depends on the specific drives that are use, since I experienced that my complete chain is limited to FW400 speed as soon as I switched on the FW400 device.

Interesting. That could explain the mixed experiences.

Before I added the FreeAgent Desk Mac, the head of the chain was a Roswill enclosure. I measured the same speeds with that. The chains that completely drop to FW400 could have a different bridge board chipset than those of us getting FW800 speeds.

 

[cube]

I would think such cool cases are repeaters.

 

[fpnc]

I've also done test with a Firewire chain with both FW800 and FW400 devices and as long as the FW800 device is first in the chain (closest to the port on the Mac) then that device remains very close to full FW800 speeds. However, if you are performing i/o to both devices simultaneously then the combined speed (for both) will sum to less than the full speed of FW800.

However, I have seen reports from others (as noted above) that some devices don't seem to allow full speed when in a Firewire chain. In my case I was testing with a FW800 Western Digital Studio Pro drive on a first generation Mac Pro (using only one Firewire port to chain multiple devices).

 

[Badger^2]

I'm looking at heading out to the Apple Store this coming week to pick up an iMac i7. My only concern is with the single Firewire 800 connection in the back.

Does anyone know if I plug hard drive #1 into the iMac with an 800 connection and then daisy chain hard drive #2 with a 400 connection from #1, do I slow down the transfer of the whole chain or just reads/writes from HD2?

They dont keep i7s in stock, FYI.

Thats about the only good thing my older AL iMacs have -- both FW400 and FW800 ports

I have 4 FW800 drives off the FW800 port and FW400 DVD drive and portable drive off the FW400 port -- nice and tidy.

 

[JYork23]

They dont keep i7s in stock, FYI.

And while that's sadly true, they do keep my Apple employee buddy in stock with his discount and all. Very handy.

I appreciate everyone with their tests and data. Too bad there's not one stock answer. Seems it's possible to retain 800 speeds, but that's dependent on the device. Thanks!