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Old 06-08-2019, 04:21 PM   #17
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Join Date: Jan 2016
Location: sydney
Posts: 483

Originally Posted by BernH View Post
You are missing the point. USB is not a drive specification, it is a data bus specification. Unless the hard drive specifications can match the usb specifications for bandwidth, the usb bus will still not be saturated.

Your reference to usb 3 and 3.1 drives is irrelavent.

The people making the actual storage devices (Samsung, Sandisk, kingston, etc.) would need to make a device that can hit the 40Gb/s speed.

The USB 4 bus will only be as fast as the device(s) feeding it up to it's maximum 40Gb/s specification. A single fast sata 3 SSD can only supply about 1/8th of that bandwidth (close to the speed of USB3 by the way), so you would need 8 SSD drives running in a RAID0 kind of configuration to saturate the 40Gb/s bus. NVME is a different story, as they are faster, and therefore would require fewer to saturate the bus, but they are also more expensive in comparison.

I don't know about what you consider a usb 4 portable drive, but in my mind an 8 drive array with the required RAID controller in the housing is not my definition of a portable drive.

My point with all of this is that the math tells us that a single SSD can not operate at the speed available to a usb4 connection, so there is no real speed benefit to the usb4 connection with a single drive, but there would be a benefit if the drives get faster or if it is an array of drives to share the bandwidth.
I am referring to these portable drives from samsung...

I am sure they will produce a usb4 drive as well.
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