How long would it take to transfer 1TB over USB 2.0?

Question

This might be a completely stupid question because it is conceivably highly dependent on the respective disk speeds. But I am thinking that there is a speed cap that is specific to USB 2.0 that would by itself define a lower limit.

How long would it take to transfer 1TB of data from an external drive to an internal drive over USB 2.0?

Solution 1

USB 2.0 has a signaling rate of 480 Mbit/s. The same article says that typical real-world throughput is "about two thirds of the maximum theoretical bulk data transfer rate of 53.248 MB/s." If my math is correct, and it probably isn't, that suggests that the best time you could hope to achieve is about 8.2 hours for 1 TB, assuming that the USB connection is the biggest bottleneck.

Solution 2

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.

Solution 3

From experience, I know USB 2.0 copies about 10Mb/sec on average (on my system).

So that would be
1TB == 1048576 Mb
1048576 / 10 ==> +/- 104857 secs
104857 / 60 ==> +/- 1747 mins
1747 / 60 ==> +/- 29 hours

So a full day and 5 hours.

Note that I use teracopy as the default copy handler of my windows (otherwise I never get the 10Mb/sec average over usb).

Solution 4

Given the variations of I/O handling by the operating system and the natural delay of starting and stopping copying (many vs few files) you are realisticly looking at approx 15 Mbit/s (from my experienve)

Theoretical values: 1 TB @ 480 MBit/s = approx 4.6 hrs

Realistic values: 1 TB @ 15 MBit/s = approx 148 hrs

Solution 5

I have seen about 4-5x faster performance with ESata vs. USB2.0 using the same external hard drive. I have a WD 1.5TB Essentials Drive, which I would back up using USB, but it was painful, taking about 4-5hrs per 100G, and running about 8MB/sec avg. I pulled the HD out of the plastic case, removed the USB to SATA board, and plugged the same HD into the SATA port from the mother board via an ESATA cable, and I can now backup 100G in less than an hour, and 250G in about 2.5hr using NovaBackup S/W. All I can say is that 2-3hrs is not that bad for a lot of data (running about 28-32MB/sec w/ESATA). Both are well/far below theoretical, but the comparison between the two is what counts.

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Comments

[Jared Harley]

The max is 480 Mbps - megabits per second, not megabytes. There are 8 megabits in a megabyte.

[dbr]

www39.wolframalpha.com/input/?i=1TiB+divided+by+53.248+MiB%2‌​Fs about 5 hours 30 minutes

[theycallmemorty]

@dbr: Your example is for a TiB.... the answer is different for a TB. What is the difference between a TiB and a TB?

[Ash]

@Jared, Thanks for the condascending comment but since when does b stand for Byte? From Wikipedia "IEEE 1541 specifies "b" as the symbol for bit".

[phenry]

You 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.

[Ash]

As your comment was voted up obviously there are others slightly confused. It's simple: M = Mega B = Byte b = bit

[phenry]

@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.

[Guffa]

The difference between a TB and a TiB is 7%.

[fretje]

Has somebody actually tried this? Because I know for sure this takes way longer than 8 hours!

[Feckmore]

1TB @ 15 Mbit/s = 148 hours... wolframalpha.com/input/?i=1TB+at+15Mb/s

[Kevin M]

+1 for not assuming that the USB connection is the bottleneck; sometimes it might be one of the drives that is under constant use.

[pavsaund]

@Traples Very correct. seems i made a typo. Should naturaly be 15 MB/s and not Mbit/s. updating answer. www08.wolframalpha.com/input/?i=1+TB+at+15+MB/s

[Joel Coehoorn]

Point of reference 100MB * 10485 ~= 1Terrabyte. So however long that 100 MB takes, multiple by 10,485.

[Ergec]

Real-world copy speed of USB2.0 is around ~15MB/s on windows. I've never seen 20MB/s and above.

[that other guy]

I've had the same experience across three machines and four USB HDDs. My best was 28MB/s (9-10 hours per TB).

[Pacerier]

@phenry, 1 TB is hardly big these days. Do we still need hours to transfer a simple 1 TB folder with USB 3.0 ?

[Syclone0044]

This is a terribly inaccurate answer. People, please downvote this. See my real-world answer below (superuser.com/a/354401/18664)

[phenry]

How 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)?

[Syclone0044]

@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]

@pavsaund must've forgotten to update his answer, so I just edited it to be accurate and much clearer. Notice in Feckmore's Wolframalpha answer he mistakenly uses 15 Mbits/s, forgetting there are 8 bits in a Byte, so the answer in Megabytes (MB) is 148/8 = 18.5. (Interesting tidbit: his Wolframalpha link has a warning atop the answer saying "Assuming megabits per second for "Mb/s" | Use megabytes per second or mebibits per second instead Assuming terabytes (base 10) for "TB" | Use tebibytes (base 2) or more instead", which probably explains the difference between my 19.5 hr answer vs his 18.5h

[SuperSafie]

I run badblocks on a 1TB (i.e. 931 GiB) disk over USB2 and took very close to 10 hours which is 26,5 MiB/s or 27,8 MB/s (if I'm not mistaken with the MB, MiB and all that)

[scjorge]

which system was that?

[kokbira]

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...

[Larry Smithmier]

+1 for the TeraCopy link.