Having trouble transferring large files from SSD startup disk to newly installed internal HDD

Question

Have just installed an additional 2TB Samsung HDD in place of my optical drive on my late-2011 MacBook Pro.
Specs:
MacBook Pro 15inch late-2011
  Model Name: MacBook Pro
  Model Identifier: MacBookPro8,2
  Processor Name: Intel Core i7
  Processor Speed: 2.4 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 6 MB
  Memory: 8 GB
  Boot ROM Version: MBP81.0047.B27
Hard Drives:
  Startup = 120GB SSD
  New HDD = 2TB SATA Samsung M9T
OS: Yosemite 10.10.1 (14B25)
Issue:
Installed my new 2TB SATA drive and it appeared OK in Finder. I was able to navigate to it and create new folders and move small files into it (under 100MB maybe)
Really want to move my iPhoto library onto the 2TB disk to free up space for Apps on my SSD, but when I try to copy/move it over it only does the first few MB then freezes and appears to timeout as the new HDD disappears from Finder and ejects itself. I'm surprised that the eject stuff shows for an internal HDD but that's a side issue.
Have read about similar issues in other OS versions, especially around external HDD and have tried the following already:
*  Looked at power management of the hard disks to stop them going to sleep
*  Have told Spotlight not to index the new HDD to prevent the indexing task causing issues
*  Both SSD and new HDD are formatted using MAC OS/X Extended (not FAT)
*  Have tried fixing permissions on both disks as I believe there can be issues in Yosemite
I'm still having a problem  despite trying the above. Struggling!
Any help much appreciated.

Answer 1

Open Disk Utility. By selecting one of the two entries for the HDD please determine how it is formatted and what partition map it is using. I suspect you did not partition or erase this drive before use. If that's true, then do this:
Drive Partition and Format
1. Open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed.
Now you can try your file transfers again. However, before you do I recommend you clone your SSD to the HDD so the latter could be used as your boot drive should it be needed. That will also create an Home folder on the HDD with the files you wish to move to it. You can then simply remove those files from the SSD to free up the space.
Clone Yosemite, Mavericks, Lion/Mountain Lion using Restore Option of Disk Utility
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
     1. Select Disk Utility from the main menu then press the Continue
         button.
     2. Select the destination volume from the left side list.
     3. Click on the Restore tab in the DU main window.
     4. Select the destination volume from the left side list and drag it
         to the Destination entry field.
     5. Select the source volume from the left side list and drag it to
         the Source entry field.
     6. Double-check you got it right, then click on the Restore button.
Destination means the new HDD. Source means the SSD startup volume.