There is a lot of false information in these answers about "theoretical" performance from people who have evidently never benchmarked USB2 HD transfer rates.
I have benchmarked many different USB2 transfers between 2.5" laptop HDs both PATA and SATA, 3.5" HDs both PATA and SATA, and USB Flash drives...
...and I have NEVER seen transfer rates exceed 35 MB/sec! In fact, any properly configured modern drive will transfer at 20-30 MB/sec, it's very rare to see the 30 MB/sec rate be surpassed. (I'm referring SPECIFICALLY to HDs transferring over USB2 here, to be clear.)
Ignore this talk about theoretical transfer rates and "60 MB/sec", etc. Although I give credit to the guys who correctly converted bits into bytes and calculated a 35 MB/sec maximum, which falls in line with my REAL WORLD PERFORMANCE EXPERIENCE.
@phenry, 1 TB is hardly big these days. Do we still need hours to transfer a simple 1 TB folder with USB 3.0 ? – Pacerier – 2015-03-16T13:39:03.333
This is a terribly inaccurate answer. People, please downvote this. See my real-world answer below (http://superuser.com/a/354401/18664)
– Syclone0044 – 2015-11-08T13:20:14.190How can it be "terribly inaccurate" if my calculated real-world maximum (53.248 × 0.66666... ≅ 35.5 MB/s) is almost the same as your experientially derived real-world maximum (35 MB/s)? – phenry – 2015-11-08T15:37:38.400
2@phenry I apologize, after reading your answer more closely, I see you're saying typical real-world throughput is "about two thirds of the maximum theoretical bulk data transfer rate of 53MB/s", which is a rather obfuscated way of saying "35MB/s", particularly after your first sentence of the answer says "480 MBit/s". (Most people don't understand the HUGE 8x distinction between MBit vs MB). So I recommend revising your answer to make the 35MB/s best-case-scenario (not really typical - more like 20-30MB/s) appear up front at the beginning of the answer and move the technical details down. – Syclone0044 – 2015-12-02T20:14:45.247
Something is wrong in that math, isn't it? 2/3 x 480 Mbit/s = 40 MB/s, and 1000000 MB / 40 MB/s takes 25000 s, that is about 7 hours... – kokbira – 2020-01-15T20:03:09.103
8http://www39.wolframalpha.com/input/?i=1TiB+divided+by+53.248+MiB%2Fs about 5 hours 30 minutes – dbr – 2009-07-20T13:44:32.887
@dbr: Your example is for a TiB.... the answer is different for a TB. What is the difference between a TiB and a TB? – theycallmemorty – 2009-07-20T13:46:43.383
11You have to use 53.248 (theoretical maximum) × 0.6666666… (real-world limit) = 35.565333… MB/s. That's about 8 hours, 11 minutes and change. – phenry – 2009-07-20T13:50:16.327
3Real-world copy speed of USB2.0 is around ~15MB/s on windows. I've never seen 20MB/s and above. – Ergec – 2013-05-28T06:28:27.157
5@theycallmemorty: 1 terabyte is (technically) 1,000,000,000,000 bits; 1 tebibyte = 1,099,511,627,776 bits. 1 short terabyte ÷ 35.5653 MiB/s = about 7 hours 27 minutes. Still quite a while. – phenry – 2009-07-20T14:03:17.423
2The difference between a TB and a TiB is 7%. – Guffa – 2009-07-20T14:15:55.597
2Has somebody actually tried this? Because I know for sure this takes way longer than 8 hours! – fretje – 2009-07-20T14:25:49.860
1+1 for not assuming that the USB connection is the bottleneck; sometimes it might be one of the drives that is under constant use. – Kevin M – 2009-07-20T15:45:29.647