Data Transfer very slow
My External hard dive takes time to be discovered when plugged in and once discovered data is transferred extremely slow. e.g 10MB Can take 3 hours. it transfers @ a rate of 52KB/ps or less.
Sometimes USB ports have different power ratings and give different speeds. Try using the port closest to the power port if on a laptop.
If your External HDD is a WD Passport, it has extra hardware that does the encryption part. The data transfer is slow probably due to improper handling like a fall or pulling off the Ext HDD while iti s still running and hasn't spinned down. (multiple times)
I believe that WD Password uses faulty SATA to USB 3.0 boards. The board starts failing at USB 3.0 and down grades the negotiations to a very slow USB speed. Perhaps 1 or 1.5 . That is why the transfer is slow.
I am working on one right now that takes 20 min just to some online to copy the data. I am copying data and it is super slow. But it is copying just be patient, get the data off first then trash it and buy a new one. I should take days even weeks. I use the (sudo find /path_to_source | cpio -pdmv /path_to_destination)
That way if it fails from a power outage OSLT you just run the command again and it skips existing files