We recently upgraded our server from a Mac Pro 2008 with OS X Lion Server to a Mac Mini 2014 with LaCie 20TB 5Big Thunderbolt 2 RAID drive. Everything is working fine with the exception of Photoshop. It does it intermittently but once it happens it will continue to do so. We get message like "Can't save to disk because of disk error" and "Can't save file because of program error" . Sometime we are able to do a "save as" and save over it. Most of the time we have to "save as" with a different file name and then rename and recopy the file. We have check permission on all the file as well as the server HD has ignore ownership checked. Again only three things changed. 1) Sever hardware change from Mac Pro to Mac Mini. 2) Server software upgraded from 10.7 Lion to 10.10 Yosemite(both have the latest update). 3) Drive when from internal on Mac Pro to External Thunderbolt 2 LaCie drive. We have no problem with Illustrator or Indesign. Only Photoshop. Anyone with any suggestion is greatly appreciated.