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Extremely slow transfer speed with 2 USB hard drives on a USB hub. How do I fix this?

Extremely slow transfer speed with 2 USB hard drives on a USB hub. How do I fix this?

Postby adaia » Mon Feb 13, 2012 1:39 am

I am sending in a MacBook with a a broken logic board for repair, and I was trying to back up the hard drive first. I wanted to clone the drive using Carbon Copy Cloner, with another brand new external hard drive. I have a USB to SATA cable to read the drive of the MacBook Pro.

I was going to use my PowerBook G4 as the conduit, but I ran into some problems, and the PowerBook could not recognize any of the drives. Apparently there's a defect where the USB ports don't provide enough electricity to run the external hard drives, so I had to purchase an AC-powered USB hub.

After purchasing the USB hub, I discovered I can only get the computer to recognize the hard drives when they are both connected to the USB hub at the same time (one of the two USB ports won't recognize anything no matter what). When I set up the clone process, I was only able to back up 3 GB after 3 hours, an outrageously slow speed.

When I began testing the drives individually, I could transfer 1 GB in less than five minutes from the MacBook to the PowerBook, and the same speed from the PowerBook writing to the new hard drive. It's only when I transfer between the two drives that things get extremely slow. I realize it should go about half as slow as normal, but this is just ridiculous. I can't back up a 250GB hard drive over 250 hours.

Is there anything I can do to speed up the process? Is there some trick that I don't know?


P.S. I realize that I might have to return the hard drive for one that uses a FireWire cable to reduce the USB redundancy, but this is something I was trying to resolve with my current setup. I'm trying to just get this done quickly without spending more money, more hassle, etc.
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Extremely slow transfer speed with 2 USB hard drives on a USB hub. How do I fix this?

Postby cynrik » Mon Feb 13, 2012 1:42 am

If that's an older Powerbook then it might not even have USB 2.0.

Even if it does, USB to USB absolutely SUCKS in throughput no matter what you're using if they're on the same bus. USB is terrible for that sort of thing.

Um...George, you might want to take a look at your numbers again. You show USB 1.1 as having a higher transfer rate than USB 2.0.
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Extremely slow transfer speed with 2 USB hard drives on a USB hub. How do I fix this?

Postby ardkill3 » Mon Feb 13, 2012 1:43 am

If that's an older Powerbook then it might not even have USB 2.0.

Even if it does, USB to USB absolutely SUCKS in throughput no matter what you're using if they're on the same bus. USB is terrible for that sort of thing.

Um...George, you might want to take a look at your numbers again. You show USB 1.1 as having a higher transfer rate than USB 2.0.
Data transfer rate....

USB 2.0 Full-speed 12MBps = 43,200MB per hour
USB 2.0 High-Speed 480MGps = 1.7GB per hour

Any more question's...
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