Question: As in the Windows 7 Disk Policy Options:

[x] Enable Write Caching on the device[ ] Turn off Windows write-cache buffer flushing on the device

Is the first the cache on the physical disk, and the second the windows cache?

(I’ve googled, but didn’t find a clear answer).

Answer: See “more information” section from http://support.microsoft.com/kb/332023:

?

Many disk devices provide enhanced ?performance through the use of an ?onboard cache, which provides ?read-ahead caching for data that is ?being read from the disk, and ?write-behind caching (or delayed ?writes or “lazy” writes) for data that ?is being written to disk. In some ?cases, it is important for data to be ?written to the physical disk ?immediately, and not retained in the ?disk’s onboard write cache to be ?written later during an otherwise idle ?moment. This prevents loss or ?corruption of this data if the disk or ?controller (wherever the write cache ?is implemented) suddenly loses power

Write caching improves disk performance greatly, so leave it on for internal hard drives.

Windows turns write caching Off for flash drives and other usb hard drives by default, normally you do not have to ever modify these settings, Windows takes care of it for you.