Recognise this scenario? You’re going out of the office for a few days but need to work on a number of important documents, normally stored on the network server. In the absence of a complex VPN connection, one solution is to laboriously copy the necessary documents before you go then copy them all back on your return, hoping nobody else has made changes in the meantime. Another is to use Offline Files, an often overlooked Windows option which, almost magically it seems, enables server hosted files to be accessed whether connected to the LAN or not.

Caching by any other name
Also known as client-side caching (CSC), Offline Files was first introduced in Windows 2000 and is based on very straightforward caching technology. Target server folders and files are simply selected for offline access and cached by the local PC to a hidden system folder (/Windows/CSC). The two copies are then kept synchronised and it’s the local files that are used when disconnected from the LAN, although to the user nothing appears to change. Network shares, folders, mapped drive letters and so on can still be used, and server held files opened and saved as normal. Moreover, the next time the PC connects to the LAN, the local files are re-synchronised with those on the server automatically.

Files to go
At the client end Offline Files is a very easy option to use. All that’s needed is a PC running either Windows 2000 Professional or Windows XP. Nothing has to be installed, although with XP you have to disable fast user switching as the two options are incompatible (Control Panel, User Accounts, Change the way users log on or off ). It’s then just a matter of opening the My Computer folder, selecting the Tools menu then Folder Options, followed by Offline Files to turn the option on (see Screenshot 1).

Few constraints are put on what can be cached although you may want to avoid large files because of the space they take up and the time required to copy them. Windows helps by stopping Access databases and other unsuitable files being marked for offline use, plus it’s possible to limit the amount of local space available for caching, the default being 10% of disk capacity. You can also tell Windows when to synchronise files and get it to display a reminder when working offline. Additionally, if the local file system is NTFS, the cached files can be encrypted - an important consideration given that you’re effectively taking documents and other files out of the office.

Having turned the feature on you then need to tell Windows which files to cache. To do that select a network drive, folder or an individual file then, from the right mouse button menu, choose Make Available Offline.

The first time you do this an Offline Files Wizard will check the base caching settings again, after which a dialog box is displayed showing progress as the local copies are created. The display icons for the folders/files concerned are then changed to include a so-called “roundtrip” arrow (see Screenshot 3) and it’s business as usual, with the selected files now accessible in their usual locations whether connected to the network or not.

Offline management
The Offline Files feature is pretty straightforward and, largely, self managing although there are times when you might need to intervene. Done using the Synchronize Manager tool in Windows XP (Start, Programs, Accessories, Synchronize), also used to manage offline Web pages.

Among other options Synchronization Manager provides support for scheduled synchronisation and different synchronisation settings dependent on the connection involved. For example, you might want to stop large files being synchronised when connecting to the network over a slow dial-up line but keep smaller documents updated all the time.

A major bonus with Offline Files is that nothing special is needed at the server, just support for the SMB (Server Message Block) protocol. That means you can cache files on Unix and Linux systems running Samba and Novell NetWare servers as well as those running Windows. On a Windows server, however, additional control of the caching process is possible via the Caching button found on the network share property page (see Screenshot 5).

From here it’s possible to stop users caching files using the Offline Files feature altogether. For example, to prevent confidential material being cached and then lost because a notebook is stolen or mislaid. Bear in mind, however, that caching is normally enabled by default whenever a new share is created, which means either changing the default or taking specific action to turn off caching every time a new share is created. Added to which caching can only be turned on or off for the entire network share, not individual files or folders.

Another option on a Windows server is the ability to set either automatic or manual caching. The default, manual caching, operates as already described, with individual selecting the files to be cached. However, with automatic caching, files are made available for offline use whenever a user opens them, without the need to expressly identify the files involved in advance. That cuts down on the work required at the client end, but note that automatically cached copies aren’t created until a user opens the server original and saves it again, at least once.

Automatic caching for programs can also be selected, enabling applications to be run when disconnected from the LAN. Again, though, some care is needed as Windows will only cache application files that have been directly accessed. Optional and rarely used components, such as a spell checker for example, won’t be cached until called upon. Added to which the files involved can be huge and there are can also be licensing implications.

In summary Offline Files can be a very useful tool for users who need regularly to disconnect from the LAN but still need to have access to server files. It’s easy to configure, costs nothing and, much of the time, is transparent to both users and network managers alike. Give it a try, there’s nothing to be lost and a lot to be gained.