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I'm copying about 4TB of data from one hdd to another and noticing abysmal speeds.
I have two external SATA 3 hdds plugged into USB 3.0 docks and connected to USB3.0 ports on Macbook Pro. MBP was idle during the copy.
Obviously, the speed is limited by disk mechanics - according to manufacturer the read/write speed is 150MB/sec. So theoretically, 1TB should take 2hrs to copy over. I'm seeing times almost double that, which means I'm getting about 80-90MB/sec.
How can I raise my transfer speed close to max speed of 150MB/sec? 150MB/s is way below the capabilities of SATA3 or USB 3.
1If your speed is 150MB/sec then it will just take 8-10 sec to copy 1 GB Data not 2 Hrs – Ali786 – 2014-08-05T16:38:52.307
> copying about 4TB of data
. 80-90 MB/s over a large set of data is quite good in my opinion. – Hannu – 2014-08-05T16:58:05.923Ensure both drives aren't sharing a single internal USB hub. – Ƭᴇcʜιᴇ007 – 2014-08-05T17:06:56.533
If you can, retest with a powered USB 3 hub. Power may be the performance-limiting factor here. – David Schwartz – 2014-08-05T17:20:52.887
For what it is worth: Practical testing just the other night - Asus HERO VI USB 3.0, i7 4770, 32GB RAM - cheap USB 3.0 to IDE 3.5" (self powered) directly connected to the MB port, an 320GB ST320620A drive. The very first GB may achieve as much as 200MB/s, then it tops out at 80 MB/s which slowly fades to 55-60MB/s as the disk comes close to full. Test with
dd if=/dev/zero bs=8k of=ON-DISK
– Hannu – 2014-08-05T18:37:40.763