Regarding the maximum transfer rate on USB2.0:
The fastest read rates I have seen so far are in the range of 29 to 33 MByte/s from Harddisks or Memory Sticks. But ... read ...
People are talking about USB2.0 protocol limits and overhead. Does anybody know what is really going on here?
At 33 MByte/s, the USB2.0 bus is clearly NOT saturated, even accounting for protocol overhead.
I connected two Mass Storage Devices (Memory Stick or HDD) to the same port via a Hub, both reading at 31 MByte/s alone. Then I tested reading from both in parallel, everyone giving approx 22, the sum was 43.8 MByte/s.
I added a third Mass Storage Device (a little slower) and got a sum of 47.0 MByte/s.
That test clearly shows that the USB2.0 resources are not completely used by 1 device alone. The results are quite the same for Windows (XP, Vista) and Linux. I still do not see the point in USB protocol which causes this limit for a single device.
The fastest read rates I have seen so far are in the range of 29 to 33 MByte/s from Harddisks or Memory Sticks. But ... read ...
People are talking about USB2.0 protocol limits and overhead. Does anybody know what is really going on here?
At 33 MByte/s, the USB2.0 bus is clearly NOT saturated, even accounting for protocol overhead.
I connected two Mass Storage Devices (Memory Stick or HDD) to the same port via a Hub, both reading at 31 MByte/s alone. Then I tested reading from both in parallel, everyone giving approx 22, the sum was 43.8 MByte/s.
I added a third Mass Storage Device (a little slower) and got a sum of 47.0 MByte/s.
That test clearly shows that the USB2.0 resources are not completely used by 1 device alone. The results are quite the same for Windows (XP, Vista) and Linux. I still do not see the point in USB protocol which causes this limit for a single device.