took Macbook Pro 10 hours to copy a 3TB drive to another 3TB drive, is that normal?
 

I have a 3TB external USB 3.0 hard drive connected to my old Macbook Pro(2014 version). The 3TB is almost full, with only about 100GB of free space left.

I bought another 3TB drive(same brand and model number) and hooked it up. I then selected all the files on the source drive and copied them to the new drive. It took a little over 10 hours for the copying to complete.

Is that normal? Or is there something wrong with my Macbook Pro or either of the 3TB drives?

Thanks!

Well, at full theoretical USB 3.0 speed of 5Gbps (625 MB/s) it should take a little over an hour. But I don't think any consumer laptop can pull full theoretical speeds.

Still, it seems you were going at about a tenth of that speed - which just so happens to be the USB 2.0 full speed. Maybe one of your devices was communicating at USB 2.0 speeds.

I did a similar thing a few weeks ago. Upgrading to a 3 TB WD portable HD up from a 2 TB WD. It took about 2 hours total. I was also using the computer during this time so that may have lengthened the process. But your 10 hours seems excessive. MY 15" MBP is the highest configuration 2014 version also.

more the problem of the drive, than the laptop (=usb controller and other)

top usb drives can do a sustained 100MB/s ...though ive never seen such. usually 60-80MB/s is what im happy to see whether in a usb stick, powered, or standalone 2.5/3.5" drive.

with that in mind, 3 terabytes at 80MB/s equates to a neat 10.5 hours

http://www.everythingusb.com/speed.html
(see the 3.5" section)

so my USB hard drives and Macbook are just fine? I guess it didn't help
that at least half of the 3TB contained my family digital photos, ranging
from 2MB(from really old digital cameras from 15 years ago) to 20MB
(current digital camera).

Real USB 2.0 speed is about 30-35MB/s. I guess these HD are 5200rpm units so 80MB/s sustained speed seems reasonable.

http://www.verbatim.com/UserFiles/Fi...203%20FAQs.pdf

Q. How much faster is SuperSpeed USB 3.0 over USB 2.0?

A. The theoretical transfer speed of USB 3.0 is 4.8 Gbit/s (600MBps) vs. 480 Mbit/s (60MBps) which is a 10X improvement. Sustained transfer speeds (real life) for external hard drives are about 85MBps for USB 3.0 and about 22MBps for USB 2.0, so about a 5X improvement but still a significant advancement in transfer speed.




yes, marginally slower if youre transferring lots of small files. either way, you're in the ballpark of performance. not OOM off

It might have been faster if you used something like carbon copy cloner to copy everything over. Still, it's a lot of data, and probably lots of files and file operations to do this copy.

-David

My math gets 660Mbps or 83MBps. That's a pretty normal real-world transfer speed. Seems as expected, IMHO.

A 3.5" hard drive will typically have a limit of 100-125MB/second, or 8-10 seconds per gigabyte. 3TB = 3 trillion bytes as drive manufacturers use it, or abour 2793GB (or GiB) using the OS/RAM sense of 1GB = 2 to the 30th bytes rather than 10 to the 9th.

If you multiply that by 8-10 seconds per GB, that comes to between 6-8 hours. There's some overhead for USB, and there's some overhead if there are a lot of small files involved. So 10 hours is a bit slow, but not totally unreasonable.

USB 2.0 is limited to 480 Mbps, which in theory is 60MB/sec but in practice is more like 50-55MB/sec usable speed. At those speeds, the drive would have taken about 14 hours to copy, so you were getting at least some advantage out of USB 3.

IT's usually considerably faster to use Disk Utility for this kind of copy rather than the Finder.

How would CLI dd compare in speed? At least in the Linux world that's the usual tool to copy drives - like dd if=OLDDRIVE of=NEWDRIVE bs=64K

It also depends on what the files are on the drive.. with a lot of SMALL files, like 0-5MB a piece (photos, mp3s, documents, etc) it can dramatically increase the normal expected amount of time to copy.