Additional Enhancements to Offline Files Introduced in Windows 7

To improve Offline Files performance and overall user experience, the following additional enhancements have been made to Offline Files in Windows 7:

• Slow-link mode enabled Slow-link mode is on by default for Offline Files in Windows 7. The default slow-link threshold in Windows 7 is now an 80-millisecond round-trip latency to ensure an optimal user experience when accessing files made available for offline use over a slow WAN link.
• Background sync Beginning with Windows 7, Offline Files synchronization between the client and the server can now occur automatically in the background without the user needing to choose between online and offline modes. This means that synchronization is now completely transparent to users and they no longer need to worry about manually synchronizing their data over slow networks (provided that the server is available, either over a LAN connection, WAN link, or VPN connection). Administrators also benefit by knowing that users' files are synchronized automatically with the server, making it easier to ensure that users' files are always backed up.
  The new background sync feature of Offline Files in Windows 7 also makes Folder Redirection more powerful and more transparent to users. For example, if you use Folder Redirection to redirect the Documents folder to a network share and have Offline Files enabled, background sync will ensure that users' local copies of documents will be synchronized automatically with copies on the network share.
  Full two-way background sync occurs whenever Windows determines that Offline Files is operating in slow-link mode. By default, network folders in slow-link mode are synchronized every 6 hours with the server plus an offset of up to 1 hour. Background sync is fully configurable by using Group Policy. For information on how to configure background sync, see the section titled "Additional Offline Files Policy Settings for Windows 7" later in this tutorial.
• Transparent caching In Windows Vista and earlier versions, when client computers had to open a file across a slow network, the client had to retrieve the file from the server even if the client had retrieved the file recently. Beginning with Windows 7, client computers can now cache remote files to reduce the number of times the file needs to be retrieved from the remote server.
  The first time that the user opens a file in an SMB share on a network server, the file is read from the server and is cached locally on the client in the Offline Files cache. On subsequent occasions that the user needs to read the same file, the client contacts the server to determine whether the locally cached version of the file is still up to date. If the local copy is still up to date, the client reads the file from its local cache. If the file is no longer up to date, the client retrieves a new copy of the file from the server. If the server becomes unavailable, the user cannot access the file-the locally cached copy of the file is not available to the user when the user is offline.
  The locally cached copy is not kept in sync automatically with the copy on the server and does not show up in Sync Center. The server must still be available for the client to access the file, either from its local cache or over the network. If the client makes any modifications to a file and then saves it, the modifications are made on the server to ensure that the server always has an up-to-date copy of the file. If the server is not available when the client tries to save the modified file, the save operation will fail with an error.
  Transparent caching can be configured using Group Policy and takes place whenever a specified network latency value is exceeded. Transparent caching is not enabled by default on fast networks (for example, those with LAN connections). For information on how to configure transparent caching, see the section titled "Additional Offline Files Policy Settings for Windows 7" later in this tutorial.
  Transparent caching can benefit users at branch offices by enabling them to access files quickly over slow WAN links by retrieving them from the client's local cache when they are available. Transparent caching also benefits administrators by reducing band width utilization on slow WAN links. Administrators can further reduce unwanted WAN traffic and improve end-user experience for file access by implementing BranchCache, a feature of Windows Server 2008 R2 and Windows 7 that enables content from file and Web servers on a WAN to be cached on computers at a local branch office.
• Offline Files exclusion list Administrators can now specify file types that should be blocked from being available for offline use. This exclusion list is configured using Group Policy by specifying the file extensions of the files that should not be made available for offline use. For information on how to configure an exclusion list, see the section titled "Additional Offline Files Policy Settings for Windows 7" later in this tutorial.
  The Offline Files exclusion list benefits administrators by allowing them to enforce organizational security policies by preventing users from storing restricted types of content, such as music or video files, on network servers. The exclusion list also enables administrators to save disk space on both clients and servers and also save bandwidth by reducing the amount of sync traffic occurring.