Offline Files in Windows XP

Sometimes users see "enable offline files" option greyed out in the Offline Files tab. This happens when the group policy is set to disable offline files. This locks the offline files UI and users will not be able to change any setting. You might have to contact the administrator of the computer domain to get the the group policy modified to enable offline files.

In Windows 2003 Server, one can not enable offline files when Remote desktop is enabled on the machine. If you do not see anything in offline files tab (like above) in Folder options windows then check if Remote desktop is enabled on the machine.




In Windows XP, one can not enable offline files when Fast user switching is enabled on the machine. If you do not see offline files tab in Folder options then check if Fast user switching is enabled on the machine.

offline files feature can be used as a tool to synchronize files between two computers, though it is not really intended for this purpose. Many laptop users face the situation that they keep the files on their laptops as well as the desktops and have to do a manual synchronization between the two when the files are modified on one machine. Or sometimes one may forget which machine has the latest modified files. All this can be avoided by using offline files.

How to use it?

• Keep the files on the desktop machine and share it and give access only to yourself.
• Enable offline files on the laptop.
• Access the share from the laptop and mark the share for offline availability.

Client Side Cache(CSC) has many configurable settings which control the way CSC can be used on the system. Some of these settings can be configured in UI directly while the remaining can be configured using group policy or registry keys.

User Interface(UI):

Open My computer -> Tools -> Folder options -> Offline Files

Here we can set the following

• Enable/Disable offline files
• Do synchronization during login / logoff
  
• Encrypt the local cache
• Amount of disk space to be used for temporary files

Offline files synchronization that takes place during user logoff can be disabled in the following way.

Log in to the Domain Controller machine.

Open the Group policy object editor( see here)

Go to Computer Configuration -> Administrative Templated -> Network -> Offline files

Now the right side pane shows a list of settings related to offline files feature. Among this select "Synchronize all offline files before logging off" by double click and it will open a window like below.



Here select the box "Disabled" to disable synchronization of offline files during logoff.
Click on 'Apply' and close the windows.

Do the following to make a network folder available offline. Offline files should be enabled before running these steps. See the post How to enable offline files in Windows XP.

• Open the network share and select the file or folder that you want to make available offline
• Right click the share or file
• Select "Make available offline"
• Now the offline files wizard starts. It asks if the sub folders also should be made offline available or not.
• Select one of these and then click next
• Now Offline Files marks the files as offline available and copies the folders/files to the local offline cache folder.
• The files/folders marked for offline availability will have a small arrow mark on the bottom left corner on their icons.

We know that in order to use a network folder in offline mode, we need to mark that folder for offline cache by right clicking and then selecting "Make available offline". But we can have few special folders which does not require this step and are still available offline. These files/folders are called administratively assigned offline files/folders. The list of these special folders can be configured using group policy.

• Go to User Configuration -> Administrative templates -> Network -> Offline files
  Now on the right side pane you can see a list of settings.
• Double click on the setting "Administratively assigned offline files" and Select the "Enabled" check box.

• Click on "Show..."
• Add the folders here
• click OK and Apply
• Close the windows

Administrators can disable logon synchronization for all users by configuring group policy setting. The steps are detailed below.

Log in to the Domain Controller machine.

Open the Group policy object editor( see here)

Go to the node Computer Configuration -> Administrative Templated -> Network -> Offline files

Now the right side pane shows a list of settings related to offline files feature. Among this select "Synchronize all offline files when logging on" by double click and it will open a window like below.



Here select the box 'Disabled' to disable synchronization of offline files during logon.
Click on Apply and OK and close the windows.

If you are getting access denied when CSC tries to synchronize offline files, the reason could be the following.

CSC tries to synchronize offline files as long as the system is on, not just when the user is logged in. Suppose user A has marked some files for offline cache and logged off. Now user B logs in to the system. CSC still tries to synchronize the user A's offline files and prompts the user B for credentials. If user B does not supply the credentials or even if the supplied credentials does not have access to the share, CSC will generate access denied error.

Fix for this problem is available from XP Service Pack 1.

If you enable "Show hidden files/folders" in Folder view options, you can see a folder named CSC in C:\windows directory. This CSC folder shows various folders named d1, d2, d3 ,....,d8 and also some files having names prefixed with 0x000..

This CSC folder is where Windows keeps the the information about offline folders. If you don't know about offline files see this post "What is offline files"

This folder can be moved to some other location by editing the registry key DatabaseLocation under the following node.
HKLM\Software\Microsoft\Windows\CurrentVersion\NetCache

What is Offline Files ?

Offline files is a feature in Windows operating systems introduced from windows 2000. This is a very useful feature for laptop users who want to access network shares even when they are not connected to the network. For this you just have to select which folders you want to use in offline mode. These selected folders will be copied by Offline files to the local disk. When you disconnect your machine from the network, all the file access requests will be redirected to the local copies by Offline Files.

What's great about it? I can manually copy the files to my laptop!

Offline Files also handles synchronization. It tries to keep the local folders up to date with the network folders. When you copy files manually, you need to sync the files periodically to ensure that the files you have on local machine are the latest. Offline files takes care of this automatically. And the whole thing is transparent from the user point of view. The files you used to access with UNC path(ex: \\server\share\file1.doc) can be accessed using the same path even in disconnected mode. So all the applications which access these network shares will continue to work without causing any issues with file paths.

It also handles synchronization from client to server. Suppose you modified files on your machine in disconnected mode. When you connect the machine to network, Offline Files copies the modified files to the network share. Offline files can also identify synchronization conflicts in scenarios like some one else modifying the same files before you sync your changes.

What versions of windows have offline files feature?

Look at the table below.

Yes - Has 'Offline Files' feature
No -Does not have 'Offline Files' feature

CSCCMD  is a client side cache utility which can be used for various Client Side Cache(CSC) management operations. Some of the operations we can perform using this tool are enabling/disabling offline files, pinning files for offline availability, listing the files/folders that are already cached, forcing a share to go offline etc. But all these operations are doable even without csccmd tool. We have UI to enable/disable offline files feature, we can also list the files in the local cache(it's using UI, not in command line though). Apart from these basic operations CSCCMD is also capable of doing some cache management operations for which there is no alternative way. Let's see one such operation.

Let's say we have pinned a share on machine A for offline availability. Now let's say the share is moved to machine B. But our offline files cache still points to machine A and tries to synchronize local cache by trying to contact machine A which is down. This will cause synchronization failures which we can see in the sync center.

In such a case one solution is to delete the local cache and mark the share on machine B for offline availability. This requires an additional effort and is not appropriate solution if the user has edited the files which are saved on the local cache but not yet synchronized with the server share. In such a case all the changes written to the local cache will be lost.

CSCCMD with moveshare switch can be used to solve this problem. This tool can update the local cache to point to the share on machine B and therafter CSC will do the synchronization with the share on machine B.
If there are any files changed locally, those also will be replicated on the share on machine B. Below is an example to update the cache with the new location of the share.


To move share from \\machineA\shareA to \\machineB\shareB run the below command.

As mentioned in previous posts, when we mark a network share for offline availability, Offline Files copies the whole share to the local CSC folder. From that moment onwards Offline Files has to take care of the synchronization of the local copies with the network share, so that whenever we disconnect the machine from the network, we will have the latest version of the files available for offline use.

CSC( offline files) synchronizes the files with the server copies at regular intervals of time. During this, it checks with the remote server if any files have been changed. If so, it replaces the local copies with the latest versions of the server share.

Users can also trigger synchronization by the following way.

• Right click on the share
• Click on 'Synchronize'

Offline files feature was introduced with Windows 2000 operating system. The way it works in Windows 2000 is more or less same as that of Windows XP and almost all the posts in this blog apply to Windows 2000 too.