before delete volume from backend storage, erase disk data to prevent data recovery, secure sensitive user data.

In some backend stores, when a user deletes a volume, the data on the disk does not disappear, his data can be recovered by some means. This brings great security risks to users, This feature is designed to solve this problem, which named safe delete. if user delete a volume with safe delete, the volume is erased by writing zero or random writing before it is deleted.