4tb hdd... is it safe??

[GenerationX]

By chance are you using MBR or GPT?
COz i remembered having those symptoms earlier in the 2TB days when MBR usage was common. The fix was to just use GPT.

Been using 2TB / 4TB drives
4TB drives are safe as they provide the sweet spot regarding UREs copared to the higher capacity drives
ANd BTW, there is no substitute for backup. Backup important data regularly...

Is not the mbr gpt issue. That one is from the start u cant see the drive liao. Mine i formated so tat i can use the drive. Manage to copy files in liao then mths later i added new files now i wan to access i realise it disappear. Actually they are my backups. Just tat now i duno which are backuped which are not. Lucky my original i did not wipe out all..
But cetain files i delete liao