Since I just installed a NAS, and I want to transfer several TB from my Mac Pro's internal hard disks (4 of them), I wanted to make it faster by connecting those hard disks directly to the NAS using an USB 3 Dock that I have a use regularly.
However, that doesn't work:
1- All my hard disks (internal as well as external used in the docks) are formatted with Disk Utility with a single HFS+ journalized partition
2- The Dock works quite fine with hard disks that have been partitioned and used from the Dock itself, both when connected to the Mac Pro or the NAS. I can transfer data like that, by doing two copies (which actually doesn't save time because there are 2 transferts instead of one).
3- Obviously the internal hard disks work quite fine when inside the Mac Pro. No issues found with First Aid or SMART for example.
4- Internal hard disks are unreadable when installed in the Dock: they do not show up in the NAS, and the Mac asks to initialize them (which I don't of course).
5- Dock hard disks are unreadable when installed internally in the Mac Pro, who asks to initialize them (which I don't of course).
So I suspect the Mac partitions or formats the hard disks differently when it's an internal hard disk vs when it's a hard disk inside some enclosure or dock.
How can I find out? Is there a way (forward looking) to format the hard disks in such a way that work both internally and installed internally in the Mac Pro.
Note that I now run Mac OS X El Capitan, but this is not a new issue. I remember having seen the same problem a rather long time ago in a different context (when upgrading an internal hard disk to a larger capacity one).