When network connections are unavailable, Windows 2000’s Offline Files can keep you going.

Take It Offline

When network connections are unavailable, Windows 2000’s Offline Files can keep you going.

• By Michael Chacon
• December 01, 2000

We’ve never been so connected as we are today. Network ports are ubiquitous in organizations; cable modems, satellite, and DSL have millions of people constantly connected to the Internet; and VPNs keep them linked to their corporate networks. This is becoming such a fact of life that a great dependency is growing on continuous access to the information we want and need. When this dependency is occasionally tested (such as when we lose our network connections), many people, including myself, don’t fare well. But take heart: Even if you can’t be physically connected, you can still be virtually connected thanks to Windows 2000’s Offline Files and a little more disk space.

Offline Files is a service built into Win2K that caches files from network shares and stores them on a workstation’s local hard drive. If you lose your network connection or if you have a portable computer that regularly disconnects, you can still view and work with files that logically reside on the network. This is a great way to ensure that you always have access to the files you’re working on without having to remember to copy them back and forth from your computer to the network. However, as straightforward as this service sounds, it’s not problem-free.

Client and Server Configuration

Let’s start with the basic configuration of Offline Files. The first caveat: Offline Files is only available with file sessions that are SMB-based (i.e. Win2K, Windows NT, and Windows 9x). So Novell, Unix, and even Win2K Terminal Server sessions need not apply. That said, there are two main steps that need to be taken before offline files are available. One is on the server side, where the shared folder resides; the other is on the client side, where the ability to select files for offline use must be enabled.

On the server where the share is—or will be—created, right-click on the sharing menu option to get Figure 1.

Figure 1. On the server side the sharing menu offers caching options for offline use.

Along with the Share name, permissions, and other configuration options, you’ll notice a button that reads Caching. This is where you configure this share for offline access. When you click on this button, you’re given the options shown in Figure 2.

Figure 2. Caching settings define how the administrator wants offline users to access network files.

The checkbox “Allow caching of files in this shared folder” must be selected or the files in this folder won’t be available for offline use. If this box isn’t checked, the menu option Make Available Offline won’t be displayed. The ability to cache files or folders is controlled by the administrator of the share that contains the original files.

Once the general permission to cache files is enabled, the administrator can configure one of three options for how those files will be cached:

• Automatic Caching for Documents—Makes files that are opened available offline whether or not the user chooses to make that file available. Files that aren’t opened by the user aren’t available offline. However, this doesn’t ensure that a file will always be available offline as these files are removed from the local cache if space is needed.

• Automatic Caching for Programs—Used for making read-only files available offline. The term “Programs” is misleading as it only pertains to the files that are opened, not all of the DLLs routinely called as various functions are selected as a part of a program.

• Manual Caching for Documents—Only allows files that are specified for offline use to be cached. Microsoft refers to this as pinning the file to the local machine. Once you select a file to be manually cached, it won’t be flushed as the cache can grow to the size of the logical disk partition.

Once the share on the server has been configured to allow the caching of files, you need to configure the client to cache files. To do this you need to select the Tools | Folder Options through My Computer or Windows Explorer and then select the menu shown in Figure 3.

Figure 3. The Folder Options tab allows you to configure the client for caching files.

This brings up the tabs that allow you to configure the views, file types, and other general characteristics of files. When you select the Offline Files tab, you get the screen show in Figure 4.

Figure 4. The Offline Files tab under Folder Options lets the administrator control synchronization, reminders and disk space allotment.

In Win2K Professional, the default for this box is checked with Offline Folders enabled (in Windows Server the default is off). Once you select the Enable Offline Files checkbox, all of the options to configure the local use of offline files are available as the defaults as shown below.

The basic configuration for Offline Files is accomplished through the following options.

• Synchronize all Offline Files before logging off—Ensures that all of the files that are cached locally are synchronized from the network share before logging off breaks the connection.

• Enable Reminders—Informs the user that the computer is not connected to the network. The message will continue to pop up until the connection is restored.

• Place shortcut to Offline Files folder on the desktop—Places a shortcut that performs the same function as the View Files button on the Offline Files tab, which I will discuss later.

• Delete—Removes the cached files that are stored in the %systemroot/CSC% directory. When you click the button, you have the option of deleting only the automatic offline files or all of the files that are cached, including the manually cached files. This doesn’t delete the original files that are on the network share. It just cleans out the cache.

• Advanced—Allows you to determine the behavior for specific shares when the connection is dropped. It gives you the option of notifying you that the connection was dropped and then allowing you to begin to work with the offline files or to never allow your computer to work offline.

The slider specifies the amount of disk space to use for offline caching, with 10 percent as the default configuration. This option only affects the automatic caching; as previously mentioned, when this limit is reached, the least recently accessed cached file will be removed. With the manual caching of files, the limit is determined by the size of the partition in which the cache is located.

Choosing Your Cache

Once you’ve configured the client to use Offline Files and the server to allow manual caching, you need to select or pin the files that you want cached. When the offline folders checkbox is selected, a new menu option is displayed that allows you to make a folder or file available offline as shown in Figure 5.

Figure 5. Once you configure the server to allow manual caching, you need to pin the files you want cached.

The first time you select a file or folder to be made available offline, you’ll be stepped through a wizard. If you’ve selected a folder with subfolders, you’ll be presented with a message to ascertain if you want all of the files in the subsequent folders to be cached as well.

After the wizard choices are completed, a hidden system folder named %systemroot%\CSC is created in which the cached files are located on the local machine and the selected files are synchronized.

It’s unwise to manipulate the files in this directory by changing their attributes and modifying them using Windows Explorer or a similar utility. The proper way to manipulate the storage area is through the View button on the Offline Files tab or through the shortcut that you may have placed on your desktop. Either method will bring up the screen shown in Figure 6.

Figure 6. When you delete a file in the Offline Files Folder, you’re only deleting the cached version.

You can manipulate files here in a similar manner, but not as fully as you can in the Explorer. However, when you delete a file here, you’re only deleting the cached version. If the file is pinned, it’ll be reached when you access the network again. Its main use is to let you know, at a glance, which files are cached, their original location, and whether they’re synchronized. The only way to properly move the Client Side Caching (CSC) folder to another drive is to use the cachemove.exe utility that comes with the Windows 2000 Server Resource Kit.

Another tool used with Offline files is the Synchronization Manager, which is also accessed through either My Computer or Windows Explorer and the Tools | Synchronize menu, which brings up the screen in Figure 7.

Figure 7. The Synchronization Manager ensures your client has the most current data when working offline.

As you can see, the synchronization manager controls cached Web Pages as well as network files. As you add Web files and network shares for local cached storage, they’re added to this screen. The Properties button shown in Figure 7 brings up the same display as the shortcut that was placed on the desktop and the View button on the Offline Files tab I discussed earlier. The Setup button brings up the screen in Figure 8.

Figure 8. The Idle tab controls how long the computer must idle prior to synchronization.

The Logon/Logoff and Idle tabs look similar but, of course, each applies only during events related to those situations. If you have multiple network connections, you can select each connection for synchronization. The On Idle tab also has an advanced tab so you can control how long the computer must idle before synchronization; the Scheduled tab allows you to set specific times for when you want synchronization to occur. Between these three options, you have complete control over the synchronization behavior of offline files.

A Few More Caveats

I have a few other caveats. NTFS compression doesn’t work with Offline Files. Also, some files—those with an extension of .db, .mdb, .pst, and others—by default, won’t come across. The reason for this is to avoid dangerous file conflicts, which can result in data loss. There’s also the possibility of conflicting document files. If another person has made changes to a file that you modified while you were offline, you’ll be given a choice of keeping one of the new versions or saving both of them with different names.

All in all, Offline Files works quite well for the client when the process is managed properly. The only real downside is the disk space that can be consumed. But with other services—such as IntelliMirror—consuming gobs of space, Offline Files is a trifle. At some point, ubiquitous broadband wireless networks might make the concept of Offline Files passé, but even those networks will break. In the meantime, you should take a look at how the Offline Files in Win2K can make your life easier when you’re on the go.