UNIX provides a standard utility called Sync, which can be used to direct the operating system to flush all file system data to disk in order to insure that it is stable and won't be lost in case of a system failure. Otherwise, any modified data present in the cache would be lost. Here is an equivalent that I wrote, called Sync, that works on all versions of Windows. Use it whenever you want to know that modified file data is safely stored on your hard drives. Unfortunately, Sync requires administrative privileges to run. This version also lets you flush removable drives such as ZIP drives.
Usage: sync [-r] [-e] [drive letter list]
|-r||Flush removable drives.|
|-e||Ejects removable drives.|
Specifying specific drives (e.g. "c e") will result in Sync only flushing those drives.