Sync: Flush all Disk Cache to Disk

In some cases, Windows might cache data before writing it to the disk. When a computer is shut down normally, all cached data is written to the disk. If you plan to shut down a computer forcibly (by initiating a Stop error or disconnecting the power), you can run the Sync command to flush all file system data to the disk. Sync, which is available as a free download, is also useful to ensure that all data is written to removable disks.
The simplest way to use Sync is to run it with no parameters and with administrative privileges, which flushes data for all disks:

sync 

  Sync 2.2: Disk Flusher for Windows 9x/Me/NT/2K/XP 
  Copyright (C) 1997-2004 Mark Russinovich 
  Sysinternals - www.sysinternals.com 

  Flushing: C E F 

To flush data for the F drive removable disk and then eject it, run the following command:

Sync -r -e F: 

  Sync 2.2: Disk Flusher for Windows 9x/Me/NT/2K/XP 
  Copyright (C) 1997-2004 Mark Russinovich 
  Sysinternals - www.sysinternals.com 

  Flushing: F