What difference between \Device\HarddiskVolume2\ and C:\?

[qyl27]

I have a strange question: in my Sandbox config, I must use \Device\HarddiskVolume2 as the start of a path instead of my system volume (aka C:\). (For using the Close/Write/OpenFilePath section).
As far as I know, \Device\HarddiskVolume2 is a pipe, C:\ is a path.