Seagate ST2000DM001 2tb - 3 drives all reporting SMART error

First - I would not assume that the ReadyNAS is reporting false errors. Keep track of the errors reported in the SMART log. This is not a log that is a ReadyNAS log, but a log on the drive itself maintained by the firmware on the drive. The ReadyNAS reads and copies the log into it's disk_smart_#date#.log file on the NAS, but cannot AFIK actually write to the SMART log on the drive.

When testing a drive with Seatools, one of the tests reads the SMART log on the drive and gives a pass/fail. It does not give the full info. There may be third party software aps that can read the SMART log of a drive when installed in a PC, but I don't know of a specific one. Many times the errors occur on restart, resync or other such activity on the drive. So it is not surprising that when you swapped the drives and restarted that you got an error on what had been a "good" drive.

Again, it depends on what these errors are doing. If they continue to climb, it is a definite indication that the drive is failing. The rate at which it is failing is indicated by how fast the errors mount, as there is a limit and then the drive will report itself dead. As I posted earlier, I have a drive that had climbing errors back in the spring, but then it stopped logging errors and is still functioning. I am just keeping an eye on it, with a spare handy.