I recently noticed excessive offline file caching during logon and logoff on a particular Windows XP domain machine (called PC1) at a customer’s Windows Small Business Server 2003 site. (Note that you can configure a server’s shared folders, or individual files within those shares, as offline files by browsing to the network item in Windows Explorer, right-clicking the item, and selecting Make Available Offline.)

PC1’s domain user (called User1) had tons of files stored in her My Documents folder, which was redirected to the SBS server. Recall that redirection of My Documents is a default setup in an SBS 2003 environment. A good reason for redirecting My Documents is so that the server’s nightly backup process backs up the folder. (For information about redirecting the My Documents folder, see the Microsoft article “Redirect My Documents folders.”)

In addition to the redirection, User1’s My Documents folder was set as Available Offline. When a network file or folder is available offline, it’s cached locally on the PC. So if the server goes down unexpectedly, the user still has access to his or her files. (For information about using the Offline Files feature, see the Microsoft article “How to use offline files in Windows XP.”) It’s possible (and in fact desirable) for a local resource (i.e., a folder or file) to be both redirected and available offline at the same time.

The problem occurred when User1 moved to an office down the hall, and another domain user (called User2) was assigned to PC1. Even though User1 was no longer using PC1, her offline file caching continued on the PC. When User2 logged on to PC1 for the first time, his redirected My Documents folder was immediately cached locally on PC1. Because offline file caching synchronization was subsequently processing for two users, logon and logoff times increased noticeably. In addition, periodic backups of the workstation were inordinately large, because PC1 contained offline files for two users.

I thought all I needed to do to stop the previous user’s file synchronization was delete the user’s domain profile. I logged on to PC1 as Administrator, right-clicked My Computer, selected Properties (which brings up the System Properties window), and selected the Advanced tab. Under User Profiles, I clicked the Settings button, selected the appropriate user, and clicked Delete. However, even after I deleted the user’s profile, offline files were still synchronizing at logon and logoff.

I contacted Microsoft Product Support Services (PSS) for help and was directed to the article “How to re-initialize the offline files cache and database.” I followed the steps under Method 1 to delete and re-initialize the offline file cache. The way this solution works is that when User1 logs on to the PC again, her offline file cache is rebuilt. So if User2 never logged back on to the machine, his offline files would never re-cache locally on PC1.

This approach worked to purge User1’s offline file cache (as well as the cache for all other users on PC1). In addition, this solution completely rebuilds the offline file cache structure, which is beneficial in case the cache has become corrupted. I’ve since discovered another Microsoft article (“Managing the Offline Files Folder: Mobile Computing”), which provides two alternative solutions, in addition to the one I used. One of these solutions is sure to meet your needs.

The upshot is that after I deleted User1’s offline file cache, User2’s logon and logoff times were 10 to 20 seconds faster. This solution will work well in your organization when users use offline file caching and move permanently from one primary PC to another primary PC.