Windows Home Server ensures that data in your shared folders is protected against failures of a single hard drive when you have multiple hard drives and folder duplication turned on. However, it is recommended that you keep another copy of the files in your shared folder on an external hard drive (USB or FireWire) and store it offsite.
Many existing backup applications, such as ntbackup.exe (included with Windows prior to the Windows Vista™ operating system), do not back up the shared folders on Windows Home Server correctly. The backup appears to be successful, but a restore may corrupt data. This is a known issue and is being investigated. If you find backup applications other than ntbackup.exe that either work or don't work with Windows Home Server shared folders, please submit feedback via Microsoft Connect at http://connect.microsoft.com/WindowsHomeServer.
To back up files in your Windows Home Server shared folders, connect an external hard drive to one of your home computers, add it as a server backup hard drive, and then use the server backup feature to back up your important shares to the drive.