- Jun 19, 2016
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I own a mid-2012 Macbook Pro Retina laptop computer, and an external USB 3.0 hard disk which I use for regular system backups via. Time Machine. I’ve noticed that the data transfer rate during backup peaks at about 30-40 MB/s. This seems closer to the USB 2.0 spec, which caps at 480 Mbit/s, or 60 MB/s. How do I check to see if my USB 3.0 external hard drive controller is operating at 3.0 speeds or not? The OS X system report lists the 500 GB external hard drive as a “Composite Device” operating on the USB 3.0 bus. It seems likely to me that the USB hard drive is probably connected at the higher USB 3.0 speed, but there is some other bottleneck occurring. Any thoughts?

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