The discussion revolves around the speed comparison between USB 2.0 and USB 3.0, particularly in the context of flash memories, external HDDs, and SSDs. Participants explore whether the distinctions in speed apply to SSDs and how connection types influence data transfer rates.
Participants express differing views on the relationship between device bandwidth and connection types, with some asserting that the connection type is the limiting factor while others seek further clarification on the concepts involved. The discussion remains unresolved on several technical points.
Participants highlight the importance of precise terminology in discussing USB speeds and device capabilities. There are references to external papers that may provide additional context but do not resolve the ongoing questions within the thread.
USB is a transfer mechanism. Any device that is capable of send/receive at USB3 speeds will be faster with USB3 than with USB2. It's irrelevant what KIND of device it is; it only matters what its transfer rates are. A device that can only send/receive at USB2 speeds will be no faster with USB3 than with USB2.mech-eng said:In flash memories or external HDDs there is a distinction as usb 2 or usb 3. USB 3.0 is faster than USB 2.0 in such devices. But what about the situation for SDD drives? Does this distinction apply to them, too?
Thank you.
Do you mean SSD (solid state drives)?mech-eng said:But what about the situation for SDD drives?
jtbell said:Do you mean SSD (solid state drives)?
newjerseyrunner said:The SSD is capable of bandwidth way higher than both USB 2 and 3.
Absolutely not. That's like saying that the size of your water tank depends on how big your faucet opening is. The SSD has a much higher bandwidth than the USB2 or even USB3 connections and if you have a faster connection, it will handle it. Conversely, if you have a very slow external drive, hooking it up to a USB3 won't make it any faster.mech-eng said:But isn't there a relation between bandwitdth and connection types, i.e USB types?
Thank you.
Or better still, connect a SSD to the PCIe bus. Seagate makes PCIe SSD's with up to 8GB/s transfer rates.newjerseyrunner said:The SSD is capable of bandwidth way higher than both USB 2 and 3. You will be limited by your connection, not the drive. I would highly recommend properly connecting it via a SATA connector.
phinds said:Absolutely not. That's like saying that the size of your water tank depends on how big your faucet opening is. The SSD has a much higher bandwidth than the USB2 or even USB3 connections and if you have a faster connection, it will handle it. Conversely, if you have a very slow external drive, hooking it up to a USB3 won't make it any faster.
yesmech-eng said:Then can we say that the bandwidth somebody can use is the lower one between the device and the connection type for the device and the PC?
Not sure I understand the question, but if I do then yes, ANY device will attempt to communicate at the highest speed possible, but that may not be a continuous function, depending on the device and the connection. Some devices (I don't think SSD's are among them) are set to communicate at discrete bandwidths. (at least that used to be the case. I'm not really up on modern communications technology)If the SSDs have a higher bandwidth than the all connection types, are SSDs using connections at a speed of connection's full speed?
phinds said:Not sure I understand the question, but if I do then yes, ANY device will attempt to communicate at the highest speed possible, but that may not be a continuous function, depending on the device and the connection. Some devices (I don't think SSD's are among them) are set to communicate at discrete bandwidths. (at least that used to be the case. I'm not really up on modern communications technology)
Because the computer (and possibly the computer on the device) will be doing other things in addition to the transfer.mech-eng said:When transfering data via usb, windows can shows the speeds. In my cases, the speeds are not constant, they are frequently changing between a maximum value and a minumum value. Why is this the case?
No, it is the communication device's bandwidth. Some devices (old dial-up modems come to mind) would transfer at a fixed rate, but if that didn't work it would drop down to a lower rate. There would generally be a handshake between devices to agree on a rate.What is "discrete bandwidths"? Isn't a discrete bandwidth you used above is device's own bandwidth?
phinds said:Because the computer (and possibly the computer on the device) will be doing other things in addition to the transfer.No, it is the communication device's bandwidth. Some devices (old dial-up modems come to mind) would transfer at a fixed rate, but if that didn't work it would drop down to a lower rate. There would generally be a handshake between devices to agree on a rate.
This thread started off discussing USB transfer mechanisms. That is a communication device. You have STORAGE <-> USB <-> COMPUTER. The USB is the communication device.mech-eng said:But there are two relevant devices, one is the storage which is pluged into the PC via a connection type and the other is connection type i.e the port and slots. Aren't we already discussing them and their bandwidths? So communication device's bandwidth is confusing to me. Would you please explain it?
Thank you.
The question raises some complexities. The terms must be clarified and qualified before they can be used to convey appropriately precise and unambiguous information. This brief (3 pages) HP paper on USB 3.0 clarifies some of the characteristics (please note that bandwidth is expressed in bits, while throughput is expressed in bytes). This full-length (145 pages) Intel paper on IO interface architecture has more scope and is more in-depth. And this SNIA (Storage Networking Industry Association) short (28 pages) SSD performance primer is reasonably rigorous without being too dry.mech-eng said:In flash memories or external HDDs there is a distinction as usb 2 or usb 3. USB 3.0 is faster than USB 2.0 in such devices. But what about the situation for SDD drives? Does this distinction apply to them, too?
Thank you.