I am transferring data from a backup to a 15" Macbook Pro mid-2012 (Non Retina). The backup is a clone of a drive of another MBP done on a 2.5" Hitachi Touro drive with a USB-3 interface. The drive in the 2012 MBB is a Fusion drive (250 GB SSD and 2 TB Firecuda drive from Seagate (5400 RPM)). The Fusion drive is encrypted with FileVault, and the 2012 MBP is running macOS Sierra. All this being said, the transfer rate I am getting is averaging at 8 MBytes/sec. Which appears to me to be very slow. According to reviews I read, USB-3 real life transfer rates and Firecuda drive write speed are both above 100 MB/sec. So where is the bottleneck? Is there a way to find out?

I must say that I am using a version of Carbon Copy Cloner that has not been validated on macOS Sierra. However, I also tried transferring my files with Migration Assistant and it was not any faster.

  • @IconDaemon I am copying files from a backup on a USB-3 drive to an MBP 2012. The 2011 MBP should not come in the equation here, and maybe I should not have mentioned that detail. – Jean-François Beauchamp Sep 22 '17 at 17:51
  • @Allan The connection from the external USB-3 drive to the mid-2012 MBP. – Jean-François Beauchamp Sep 22 '17 at 17:52
  • I edited my question to remove unnecessary details and make it less confusing. :) – Jean-François Beauchamp Sep 22 '17 at 17:55
  • Merci. I would assume that the overhead from the FileVault encryption of the incoming data may be adding to the decreased data transfer rate. Combine that with the hundreds of thousands, if not millions, of files that are being processed, and another factor is added to the mix. – IconDaemon Sep 22 '17 at 18:02
  • Not sure I would use CCC to go to an encrypted volume (does that even work?) I would probably clone first then encrypt after. That said...I would probably do a clean install versus a clone then migrate after. Now, issue the command system_profiler SPUSBDataType and post the output by editing the original question – Allan Sep 22 '17 at 18:07

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