What's app backup?

我想backup what's app conversation
但我發現Databases folder 裡有一個msgstore.db和數個msgstore-date.db的file.
當我想copy and paste的時候，有幾個msgstore-date.db的files是copy不到的，當我按下copy and paste to other folder，發現它沒有反應!
想問下這是什麼原因?
copy 唔晒點做backup?