Will USB 3.0 Work As Fast On a USB 2.0 Port?

**tedalin** · December 5th, 2010, 03:47 PM

I got XP SP3 with usb 2.0 ports. Will a usb 3.0 flash drive work as fast in a 2.0 port as it does in a 3.0 port?

**Ferrit** · December 5th, 2010, 04:37 PM

A usb 3 what?
And I would say frankly no.
If there is anything in there that is USB 2 it will slow
to that speed

**tedalin** · December 5th, 2010, 08:07 PM

Originally Posted by Ferrit

A usb 3 what?
And I would say frankly no.
If there is anything in there that is USB 2 it will slow
to that speed

hi, ferrit... i meant a usb 3.0 flash drive... sorry about that.

**Ferrit** · December 6th, 2010, 10:17 AM

No it cant as the port which transfers is USB 2 you said.
You need both USB 3 ports as well as USB 3 devices

**tedalin** · December 6th, 2010, 10:43 AM

Originally Posted by Ferrit

No it cant as the port which transfers is USB 2 you said.
You need both USB 3 ports as well as USB 3 devices

Wait a minute.. i read from many sources that 3.0 usb flash drives are compatible with usb 2.0 ports. so what are you talking about?

**Ferrit** · December 6th, 2010, 12:47 PM

Sorry if you are confused.
The USB 3 device "WILL: work in a USB 2.0 port yes.
But it likely will not work at USB 3 speeds

**tedalin** · December 6th, 2010, 03:11 PM

Originally Posted by Ferrit

Sorry if you are confused.
The USB 3 device "WILL: work in a USB 2.0 port yes.
But it likely will not work at USB 3 speeds

ahh.. gotcha.. thanks ferrit... one more question. can you recommend a usb 2.0 flash drive with fast copy-to and copy-from speeds?

**CeeBee** · December 6th, 2010, 04:17 PM

Originally Posted by Ferrit

Sorry if you are confused.
The USB 3 device "WILL: work in a USB 2.0 port yes.
But it likely will not work at USB 3 speeds

I think he meant "will the performance of my USB3 stick be the same in a USB2 port?"
The answer is yes, should be about the same, the stick will fall back to USB2 mode, but the USB speed is NOT the bottleneck (USB2 is 480MBits/sec=60Mbytes/sec), it's the read/write speed of the memory which is in the 10Mbytes/sec range.

**slgrieb** · December 10th, 2010, 07:01 PM

Originally Posted by CeeBee

I think he meant "will the performance of my USB3 stick be the same in a USB2 port?"
The answer is yes, should be about the same, the stick will fall back to USB2 mode, but the USB speed is NOT the bottleneck (USB2 is 480MBits/sec=60Mbytes/sec), it's the read/write speed of the memory which is in the 10Mbytes/sec range.

Hold on there a minute, buckaroo! Are you saying that my drive performance is limited more by my hardware than the interface? So, if I have a hard drive that can only deliver sustained read rates of like 30 Mps, then it really don't matter if my controller can deliver about 4 Gazillion Mbps data transfer rate? 'Cause if that's true, you're sayin' that a whole buncha common perceptions about performance are dead wrong! Next thing ya know, ya'll be sayin' that more processor cores ain't necessarily better!

**Platypus** · December 11th, 2010, 05:36 AM

Well, if everything else remains the same, I'd have to say a device with a lower inherent transfer rate on an interface with greater maximum bandwidth than the device, will not increase its performance simply by being accessed through an interface which has an even higher maximum bandwidth as its only difference.

So for example the sustained transfer rate of a hard drive which cannot saturate the SATA interface will not necessarily improve on a SATA II interface. A burst transfer from the drive cache which can saturate SATA will become faster on SATA II.

This however assumes there is no difference in the efficiency of the protocols, which could improve say latency. That could be significant for a block device, and performance could be enhanced independent of the probably non-beneficial maximum throughput.

Something like this could explain why people report USB2 devices perform a little faster on USB3 interfaces. It might also mean a USB3 device could slow down a bit on a USB2 interface, even if its throughput doesn't approach the USB2 maximum, because the USB2 interface has more overheads. You'd have to do comparisons to find out.

**CeeBee** · December 13th, 2010, 08:36 AM

Originally Posted by slgrieb

Hold on there a minute, buckaroo! Are you saying that my drive performance is limited more by my hardware than the interface? So, if I have a hard drive that can only deliver sustained read rates of like 30 Mps, then it really don't matter if my controller can deliver about 4 Gazillion Mbps data transfer rate?

Absolutely. Particularly for a memory stick where you have no cache... You aren't going to read/write faster than what the stick can do.
For a hard drive the story is different as you have some cache, data may be read/written in larger chunks and cached.
However for a memory stick more data is sent only after previous reads/writes are completed.

**tedalin** · December 15th, 2010, 11:13 AM

Originally Posted by CeeBee

Absolutely. Particularly for a memory stick where you have no cache... You aren't going to read/write faster than what the stick can do.
For a hard drive the story is different as you have some cache, data may be read/written in larger chunks and cached.
However for a memory stick more data is sent only after previous reads/writes are completed.

Hi, ceebee.. I'll be getting a usb flash drive soon, the Corsair 32GB Flash Voyager GTR. I'll use it to make an image (backup) of my whole computer. Now, what should I format it as? NTFS? FAT? or FAT32? What are the advantages/disadvantages of each? And which format is fastest for the highest copy-to speed possible, given that I want to backup my computer, which is 27GB big?

**CeeBee** · December 15th, 2010, 04:24 PM

Originally Posted by tedalin

Hi, ceebee.. I'll be getting a usb flash drive soon, the Corsair 32GB Flash Voyager GTR. I'll use it to make an image (backup) of my whole computer. Now, what should I format it as? NTFS? FAT? or FAT32? What are the advantages/disadvantages of each? And which format is fastest for the highest copy-to speed possible, given that I want to backup my computer, which is 27GB big?

The best is an external drive if you ask me. Much faster, 10x bigger for the same price.
FAT supports maximum 2GB partition so it's out of question.
FAT32 supports max 4GB files so depending on the backup software it may or may not be an issue
NTFS is not supported by all flash drives
YMMV.

**tedalin** · December 15th, 2010, 06:45 PM

Originally Posted by CeeBee

The best is an external drive if you ask me. Much faster, 10x bigger for the same price.
FAT supports maximum 2GB partition so it's out of question.
FAT32 supports max 4GB files so depending on the backup software it may or may not be an issue
NTFS is not supported by all flash drives
YMMV.

Hi, ceebee. Theres something i dont understand. I got an old 8GB usb flash drive that I used to make an image of my hard drive, which was 7GB. That usb flash drive was formatted to fat32. So, how is it possible that I was able to copy a file greater than 4GB onto it, when you say that fat32 doesn't allow files greater than 4GB?