Is USB 3.0 slower than it should be?I

  Housten 16:38 19 May 2015

Good Afternoon, Gentlemen,

I know what I am about to ask will probably annoy some people, but I have been getting annoyed, myself, which is why I am asking for what I suppose is confirmation - or not - of what Figures I have obtained.

I recently got a desktop unit, and it has 2 USB 3.0 at the back and one at the front, together with 4 USB 2.0 at the rear and 2 at the front. I have two external hard drives one of which was connected to the rear - and which has to be switched on - and the other is computer powered; both of these are USB 3.0. It seemed to me that the one connected to the front was not saving data as fast as the one connected at the back. I have also purchased an extension lead which is supposed to be specifically 3.0.

What I have done is create a folder on my 'C:\' from a couple of folders on that drive to use as a standard data amount to be downloaded as a test. The total size was 9.58 GB in 24,170 files. When I connected the computer powered drive to the USB 2.0 at the front it took 5 minutes 56 seconds to download the folder, and when connected to the USB port at the front it took 2 minutes 38 seconds. I then connected the USB 3.0 cable to a rear USB 3.0 port and the time taken was 2 minutes 37 seconds. Connecting the drive directly to the rear port took 2 minutes 41 seconds.

Obviously the times when the drive is connected to a USB 3.0 port are consistent, but what is worrying me is that everything you seem to read states that USB 3.0 is 5 times faster than USB 2.0. Well not on my computer it isn't OR have done something wrong somewhere or is there something else I should be doing?

I would be very grateful for any replies and thank everyone in advance for any reply made. Thank you, Gentlemen, for taking the time to read this.

  ukbod2009 08:42 21 May 2015

The simple answer is Yes. USB nominally should be able to manage uo to 10 times the speed of USB2. That said you`d be hard pushed to find anyone who says it can do that.

I have memory sticks for USB 3 and they rarely exceed 4x. I guess its like broadband speeds 76 at the box - 34 at the house.

  Fruit Bat /\0/\ 11:24 21 May 2015


To get the extra speed the device and connecting cable must be USB3 compliant. There is an extra connection in the socket for USB3, 5 contacts instead of 4.

USB2 will work normally in a USB3 port

I have 2 external USB3 drives a WD Elements 2Tb 3.5inch seperately powered and a WD My Book 1Tb 2.5 inch powered from the USB3 socket. Both give me about 5 times faster speed.

However even though the are connected all the time if I haven't used them they seem very slow to "initialise" but once going are fine.

  Batch 13:05 21 May 2015

The theoretical speed of USB3 may be 10 times USB2, but there are other considerations that come into play. For example:

  • A mains powered external HDD (ExtHDD) may spin faster than a USB powered one. Typically a USB powered one will be 5400rpm. Mains powered may be 7200rpm (or possibly even higher).

  • The speed that the heads move in and out across the disk (seek time) will also have a large impact.

  • The density of the storage of the physical disk will affect speed. A single platter 2TB disk will (everything else being equal) be faster than a 500GB single platter disk. In particular because fewer "seeks" will be required for the"TB one because more information can be stored on each cylinder (i.e. it is more dense).

  • Whether write caching is turn on or off will affect speed. ExtHDDs typically have write caching turned off (to protect against data loss when unplugged).

Copying large numbers of files is also NOT a good test of speed. A slower disk (e.g. slower for the reasons listed above) will take a lot longer to copy as each file has to have a (set of) file table entry(s) created. File tables are located on a different part of the disk to the files themselves. In simple terms this means that at least two "seeks" have to be made for each file - this can have a huge impact on timing.

A better test is to copy a single large file, e.g. several gigabytes. Note that the file systems of the disks needs to be NTFS to handle files greater than 4GB.

You could also try turning on write caching for the disk (although, if you do this, I would make sure to turn it back off again afterwards).

A couple of other things that could affect speeds. Windows Indexing may start to access the disk (at the same time) and so slow things down. Also other software may try to access at the same time (I find that the "Defense" part of my Comodo Firewall software can start cataloguing ExtHDDs).

Lastly, connecting ExtHDDs to a USB port via an extension cable doesn't always work well. Note sure if this is due to not enough power getting to the drive or signal delay issues or something else.

  Batch 13:16 21 May 2015

A further point on the "density"aspect:

A 1TB 2.5" drive will (everything else being equal) be faster than a 3.5" 1TB drive. I.e. the physical disk is smaller and so the data is packed more densely.

  Fruit Bat /\0/\ 13:48 21 May 2015

Moving 4Gb films to my USB3 external 2Tb 3.5inch speeds are 115Mb/s

  Housten 14:25 21 May 2015

Good Afternoon, Everyone,

Many thanks to all of you for your informative replies.

Whilst looking around to see if there are any programmes that would/should be quicker than Windows, I found a programme called "Fastcopy". I read a few bits about the programme and they all inferred that it was very fast. Weeeelllll, I hate to disagree buuut I have done some similar copying as I mentioned in my original query.

I created a "Temp" folder on my 'C:\', and copied 3 folders into it. This amounted to 11,981.7 MB, in 23043 files. Using 'Fastcopy' I copied this "Temp" folder to a 64 GB pen drive, then my computer powered 1 TB external hard drive, then deleted both of these folders and repeated the same copies but just using the standard Windows copy programme. The times I got were - in the order listed above - 418 seconds, 372 seconds, 370 seconds and 272 seconds. As you can see in both cases the hard drive was faster than the pen drive - not entirely surprising. But what I find really gob smacking is that this supposedly fast copier doesn't even beat Windows whether it is a hard drive or a pen drive.

What I will ask is this: Does anyone know of a programme which will copy faster than Windows? My operating system is Windows Home Premium 64Bit, with 4 GB of DDR 3 ram. If any other details are required by anyone I can supply these.

  Batch 15:17 21 May 2015

I think you find it very difficult to make absolute comparisons due to there being so many variables.

Copy the same file twice (to the same device and using the same copy software) can give wildly different results, I guess due to the source disk drive (and even maybe Windows to some extent) caching some of the data. Although with very large volumes of data caching is much less likely to occur.

The other thing to bear in mind that rated USB3 speeds (i.e. the theorectical maximums) far exceed the speed that any hard disk can achieve on reading, let alone writing. Although SATA (esp. SATA-III) has high rated transfer speeds, those are the transfer speeds of the electronics in an ideal situation. A mechanical hard disk cannot hope to even get near that. The best the hard disk can do is when requested to read some data which happens to be all located in the cylinder that the heads are on at that instant. In that case the data can be picked up very quickly (the deciding factor is the speed of disk rotation). Once the heads have to move (even to an adjacent cylinder) the speed drops dramatically.

To get anywhere near the best out of SATA (and USB3) one really needs to be using SSDs, not HDDs as one then avoids a mechanical disk.

  Housten 16:39 21 May 2015

Good Afternoon, Batch,

Many thanks for your reply, and illuminating my lack of knowledge of what actually happens when file transfers are carried out. I think I will stick to Windows when doing transfers as it would seem to be about the fastest anyway, and why use another programme when you have one that's works 'so well'???????

Many thanks for the time and trouble you took.

  Batch 18:49 21 May 2015


Glad to help.

The internal workings and dynamics of hard disks are a massive topic in their own right. Some very clever stuff happens behind the scenes.

I have to say that whenever I stop to think about what is packed in to such a tiny package I'm gobsmacked. I know that some may say that SSDs and flash drives also pack an awful lot in (in the way of storage). But hard disks are so much more (e.g. drive motors, read / write head servo motor, the disk(s) itself, read/write heads, accelerometer) plus the microscopic operating precision (at incredibly high speeds) and reliability that is packed in is just amazing.

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