Today, the CSC team (the people who bring you Offline Files in Windows 2000 and Windows XP) was helping a customer understand the ramifications of the policy "Do not automatically make redirected folders available offline." If you're in a situation where you've made a special folder available offline -- a folder such as My Documents -- and not all of the files you expect to see are available when offline, it's worth checking this policy setting.
In Windows 2000, when a special shell folder (such as My Documents) is redirected by the Folder Redirection feature (as opposed to directly modifying registry keys), Folder Redirection pins the top-level directory entry and its desktop.ini file if one is applicable. No other files or folders are pinned by that operation. The objective of this minimal operation was to keep the Windows shell operational when the redirected resource becomes unavailable. The goal was not to provide offline access to the redirected content. In order for files or subdirectories to be available offline, the contents of the root directory of the redirected folder (and optionally all of its subfolders) must be pinned either manually by the user or administratively through Group Policy. Once the root directory of the folder is pinned in this way, Offline Files now considers the redirected folder to be "pinned" and the normal semantics of a pinned folder are realized.
We received feedback from several large Windows 2000 customers that their expectation differed from the as-designed behavior. These customers expected that the redirection of a shell folder implies the offline availability of that folder and all of its content. They did not want to take the additional steps of pinning the redirected folder manually or through Group Policy. As a result, the default behavior in Windows XP was changed so that Offline Files automatically pins the contents of a redirected shell folder (again, when redirected by the Folder Redirection feature).
It is important to note that the act of redirecting the folder still does not pin the content. Redirection pins only the folder root directory and its desktop.ini file if applicable. This is so that the process of redirection can complete relatively quickly. Offline Files then later pins the contents in the following situations:
- During a logoff synchronization, we always scan the contents of redirected shell folders pinning files not already pinned, regardless of the "sync all files before logging off" setting. There is one exception. We do not do this operation if the associated network path is considered "slow".
- The code that processes the "Administratively assigned offline folders" policy also pins the unpinned contents of redirected shell folders. This behavior was added to address the scenario where users tend to not log off.
There are several reasons why a customer may not want to use this new default behavior.
- It is relatively expensive.
- To retain consistency with Win2000 clients
Anticipating that some customers might not want this default behavior, we introduced the "Do not automatically make redirected folders available offline" policy. With this policy enabled, the behavior is equivalent to Windows 2000 as described earlier.