We have been tipped about an apparent bug in OS X 10.7 Lion which relates to moving files using Finder. The bug, which seems to occur sporadically, has quite a few users getting more than a little concerned about data migration. The issue, which doesn’t affect everyone, appears to show up when a user tries to copy files from external drives, either portable hard drives or USB sticks. File transfers from the source drive can be started and then the files themselves can then disappear from the destination drive once the copying has apparently been completed.
The issue has already been illustrated in several sources including forums at ArsTechnica and MacRumors as well as several discussion themes (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 ) in Apple’s support forums. The problem can apparently be rectified by using a terminal command to kill and restart the Finder (killall Finder && open /System/Library/CoreServices/Finder.app), but it’s worth taking notice of, especially if users immediately delete files from the source drive without confirming they have properly copied over. Additionally, the problem does not seem to affect files that are copied using AirDrop.
It’s likely this will be fixed pretty soon in a future update to Lion, especially given the coverage in Apple’s Support Forums, but keep an eye out when you are copying large files in Lion from one drive to another.
Thanks to Anonymous for the comprehensive tip.