I have replaced my optical drive in Macbook Pro mid 2012 with Optibay disk - Hitachi Travelstar 5K1000 1TB internal harddrive (6,4 cm (2,5 inch), 5400rpm, SATA III). I have formatted it to Mac OS Extended (Journaled). When I try to copy few big files - approximately after 10 min of copying I get this error message
and the drive disappears from disk utility and is only visible in the System Information menu as unknown. It appears again only if I do the safe boot and then again boot normally. Could you please help me. Thanks.