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What's New in Offline Files

Veröffentlicht: Januar 2010

Betrifft: Windows 7, Windows Server 2008 R2

Offline Files (also known as Client Side Caching or CSC) makes network files available to an end user when a network connection to the server is unavailable or slow. When working online, file access performance is at the speed of the network and server. When the server is unavailable or the network connection is slower than a configurable threshold, files are retrieved from the Offline Files folder at local access speeds.

What are the major changes?

The major changes to Offline Files for Windows Server 2008 R2 and Windows 7 include significantly improved wide area network (WAN) file access and an improved network file experience for remote users.

Who will be interested in this feature?

The following groups might be interested in these changes:

  • Administrators that want to centralize data from client computers for administrative tasks such as backup.

  • Network administrators that want to optimize bandwidth usage and enhance the experience of users in branch offices who access files and folders that are hosted by corporate servers located offsite.

  • Users that want to continue to access network files if there is a network outage.

  • Mobile users that need to access network files while working offline or over slow networks.

What new functionality does Offline Files provide?

New functionality for Offline Files includes the following:

  • Fast first logon

  • Usually Offline support with Background Sync

  • Exclusion List

  • Transparent caching

Fast first logon

Fast first logon is a new feature that frees users from waiting while files are copied to the server the first time they log on after a Folder Redirection policy has been applied that redirects the path of a user folder to a network location. It also optimizes network usage on WAN links by synchronizing files as a background task. Prior to Windows 7, after a policy was applied that redirected a user’s folder to a network location, the user had to wait while the contents of the folder were moved to the new location. This process could take a considerable amount of time if there was a large amount of data to move and the network was slow. On Windows 7, as long as Offline Files is enabled (it is on by default), the user must wait only for Windows to move the files into the local Offline Files cache. After the files are moved, the user logs on and is free to perform other tasks while Windows synchronizes the locally cached data over the network as a background task.

Usually Offline support with Background Sync

Usually Offline support provides remote and branch office users with faster access to files that are located in a network folder across a slow network connection. Windows 7 enhances this feature by including Background Sync, a feature that synchronizes Offline Files in the background, ensuring that the server is frequently updated with the latest changes. When a client computer’s network connection to a server is slow (as configured by the administrator), Offline Files automatically transitions the client computer into an “Offline (slow connection)” mode. The user then works from the local Offline Files cache. On Windows 7, Background Sync runs at regular intervals as a background task to automatically synchronize and reconcile changes between the client computer and the server. IT administrators can configure synchronization intervals and block out times. With this feature, users no longer must worry about manually synchronizing their data with the server when working offline.

Exclusion List

The Exclusion List feature reduces synchronization overhead and disk space usage on the server, and speeds up backup and restore operations, by excluding files of certain types from replication across all Folder Redirection clients. Prior to Windows 7, all files in an Offline Files folder were replicated to the server. This often meant that a users’ personal files or large files not relevant to the enterprise were replicated to one or more servers, thereby consuming disk space and slowing backup and restore times. On Windows 7, administrators can use the Offline Files Exclusion List feature to prevent files of certain types (for example, MP3 files) from being synchronized. The list of file types is configured by the IT administrator by using Group Policy.

Transparent caching

Transparent caching optimizes bandwidth consumption on WAN links and provides near local read response times for mobile users and branch office workers that are accessing network files and folders that are not explicitly made available offline. Prior to Windows 7, to open a file across a slow network, client computers always retrieved the file from the server, even if the client computer had recently read the file. With Windows 7 transparent caching, the first time a user opens a file in a shared folder, Windows 7 reads the file from the server and then stores it in the Offline Files cache on the local hard disk drive. The subsequent times that a user opens the same file, Windows 7 retrieves the cached file from the hard disk drive instead of reading it from the server. To provide data integrity, Windows 7 always contacts the server to ensure that the cached copy is up to date. The cache is never accessed if the server is unavailable, and updates to the file are always written directly to the server.

Transparent caching is not enabled by default. IT administrators can use a Group Policy setting to enable transparent caching, improve the efficiency of the cache, and configure the amount of hard disk drive space that the cache uses.

What settings have been added or changed?

There are three new Group Policy settings for Offline Files and one setting, “Configure slow-link mode,” that has changed. Configure slow-link mode is enabled by default on Windows 7 and Windows Server 2008 R2. It controls when computers running Windows 7 or Windows Server 2008 R2 transition to the slow-link mode. See the Local Group Policy Editor for descriptions of the new settings listed in the following table.

Group Policy settings


Setting name Location Previous default value (if applicable) Default value Possible values

Configure Background Sync

Computer Configuration\Administrative Templates\Network\Offline Files


Not configured



Exclude files from being cached

Computer Configuration\Administrative Templates\Network\Offline Files


Not configured



Enable transparent caching

Computer Configuration\Administrative Templates\Network\Offline Files


Not configured



Configure slow-link mode

Computer Configuration\Administrative Templates\Network\Offline Files



Not configured



How should I prepare to deploy this feature?

The best way to implement Offline Files in a domain environment is by using Group Policy. You configure Offline Files by using the Offline Files snap-in of the Local Group Policy Editor.

Which editions include this feature?

The Offline Files feature is available and enabled by default on the following client operating systems:

  • Windows 7 Professional

  • Windows 7 Enterprise

  • Windows 7 Ultimate

Offline Files is available on all editions of the Windows Server 2008 R2 operating system.

Does it function differently on some editions?

This feature is turned off by default on Windows Server operating systems. To enable Offline Files on server operating systems, you need to first install and enable the Desktop Experience feature by using Server Manager. After installing Desktop Experience, on the server, click Start, and in the Search box, type Sync Center. In the Sync Center dialog box, click Manage offline files. On the Offline Files General tab, click Enable offline files, and then click OK.

Is it available in both 32-bit and 64-bit versions?

Yes, Offline Files is available in both 32-bit and 64-bit versions.

Additional references

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