Disk Drive, "REFRESH" What does this do?


Greetings, I have the Zomdo Replay system. In the NVR user interface in “general settings”, “disk drive info” there is an Button/Option near the bottom of the screen to the left of “format” that says “REFRESH”. Exactly what does REFRESH do.? I have the “Zmodo NVR Full Manual” PDF and there is no mention of “REFRESH” in the document. The “Disk Drive info” on pages 22 and 23 show the “REFRESH” button / option, with no explanation. ?

Thank you in advance for your help.
Mike H