Power Up Offline Files

A feature for mobile users.

• By Don Jones
• November 01, 2003

Offline Files is a great feature included in Windows 2000, XP and 2003, allowing mobile users to keep their files on a file server but still have copies with them when they travel. Offline Files’ default policies are even well thought-out, preventing users from caching file types, such as Access databases, where Windows can’t really figure out whether to keep the mobile user’s cached copy or the server copy. Windows Server 2003 even includes support for encrypting cached files by using EFS, which helps ensure that those mobile copies are safer from prying eyes. But there’s a lot you can do to power up Offline Files in your environment.

By default, Offline Files only caches the files in a folder marked for offline use. In other words, when a user right-clicks a folder and selects “Make available offline,” only the files in that folder—not the subfolders—will be available. Users don’t always realize this, since most operations on a folder do cascade down to subfolders. Fortunately, you can control that default behavior through Group Policy, either centrally from Active Directory or locally through a client’s Local Group Policy Object.

The policy you’re after is located under Computer Configuration | Administrative Templates | Network | Offline Files. The policy is named “Subfolders always available offline,” and you simply have to enable the policy to ensure that subfolders will always be available. Of course, you need to consider what this can do to the drive space on your client computers, as they’ll potentially be caching many more files. While you’re there, edit the “Files not cached” policy and make sure any database file types or other difficult-to-synchronize file types are listed so that Offline Files won’t try to grab them. If you’re concerned about security, look for XP’s “Encrypt the Offline Files cache” policy, which encrypts the entire cache using EFS.

Speaking of client-side disk space, the disk cache used by Offline Files is located, by default, on the system drive, which may not be the most convenient location for your client computers. Fortunately, you can move the cache to any location you want. You’ll need a Resource Kit utility named Cachemov. exe. You must be a local administrator on the client, and you can only move the cache to fixed disks. Also, be careful not to move the cache to any volume whose drive letter might change for some reason, as that’ll most likely cause Offline Files to stop working.

To accomplish the move, just run Cachemov.exe -unattend d:\, where d is the drive letter to which you want to move the cache. Check the Application event log for any errors. By the way, Cachemov is actually a GUI utility. If you’d prefer to click buttons rather than using the command line, just run the tool with no parameters and the GUI will appear. And a bit of extra advice: Always put the cache on an NTFS volume. You’ll get slightly better performance, the option to use EFS and the protection of NTFS permissions on cached files.

By default, Offline Files tries to synchronize whenever any network connection becomes available. It’s pretty annoying when you bring the laptop home from work and it tries to find file servers on your home’s wireless LAN. You can ratchet down the enthusiasm and configure Offline Files to only try synchronization when a specific network connection becomes available. To do so, open the Synchronize tool from the Accessories folder on the Start menu. Then click Setup and choose only your office LAN connection from the “When I am using this network connection” box. Then just choose the items you want synchronized and you’re good to go. You won’t have to put up with annoying delays or synchronization messages when you know you’re not connected to the right network to begin with.

Unfortunately, Offline Files can’t tell the difference if you use the same physical connection—such as a built-in Ethernet connector—for both your home and office networks. Consider using a USB NIC or some other alternate connection at home to give Offline Files a way to know where you are.