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I have a new laptop with USB 3.0 ports, and a new SATA 5200 rpm hard drive I just put into a new USB 3.0 enclosure.

I am copying my backups from the local hard drive to the new USB 3.0 hard drive/enclosure. It has settled at 26.1 MB/sec.

Is that the speed I should expect, or might something be wrong?

Thanks.

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The performance you see should be completely controlled by the performance of the hard drive itself. If you tell us the make and model, we can look up the rated and measured performance and see if your numbers are typical. – David Schwartz Aug 25 '11 at 22:40
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USB3 operates at higher speeds than SATA can handle, so optimally you should notice no difference between USB3 and an internal drive of the same type. In my experience with my own drive, I've noticed this to be true.

As for exact speeds, SATA 2 operates at 3 Gb/s optimally, which gives a maximum bandwidth of ~384MB/s. SATA 1 operates at 1.5 Gb/s I believe. You won't get anywhere near that with a 5200rpm drive though unfortunately. 25-30MB/s doesn't sound overly low to me.

The best test would be to connect the drive internally and test it there. If it's getting the same sort of performance, then see my first paragraph. If not, then there may be other issues coming into play.

EDIT: I did a benchmark of my own USB3 drive using HD Tune which is a caddy providing a RAID1 of two SATA2 5900rpm drives. I'd expect these to operate at about 1.5-1.7 times better than the drive you describe, which is what I got as well. The fact these numbers line up would indicate to me that both our results are in fact capped by the drives in use, not the bandwidth provided by USB3.

HD Tune drive benchmark

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While USB 3.0 can theoretically attain 3.2 Gbit/s, I doubt anyone will get even a third of that in practice. SATA is almost always going to be faster. – CajunLuke Mar 16 '11 at 0:13
@CajunLuke I have a USB3 raid 1 array, and it runs beautifully, I can play games off it at least as well as I can off my older internal SATA 2 drives. I've not noticed any drop in performance at all. While SATA2 can theoretically attain 3.0 Gbit/s, I've never attained that in practice either. – Matthew Scharley Mar 16 '11 at 0:15
@CajunLuke It depends entirely on what you spend on a harddrive. If you buy a $30 SATA1 5200rpm drive, then you have to expect bad performance. – Matthew Scharley Mar 16 '11 at 0:21
Good point. I've always had poor performance with any USB 2 device (haven't used any 3.0 devices yet), so I had little hope for 3.0. – CajunLuke Mar 16 '11 at 4:27
@CajunLuke added a benchmark for my drive, you may be interested. – Matthew Scharley Mar 16 '11 at 8:45
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