WINDOWS 1002000 PROFESSIONAL RESOURCE KIT [Electronic resources] نسخه متنی

Using Offline Files and Folders

Offline Files provides access to network files and folders from a local disk when the network is unavailable. This feature is particularly useful when access to information is critical, when network connections are unstable and nonpermanent, and when you are using mobile computers. This section discusses how Offline Files works and how to manage computers using Offline Files.

For specific information about using Offline Files with mobile computers, see "Mobile Computing" in this book.

Overview of Offline Files and Folders

Any shared file or folder on a Microsoft network can be made available offline. You can make files available from any computer that supports server message block (SMB)--based File and Printer Sharing, including Microsoft® Windows® 95, Windows 98, and Windows NT 4.0. Offline Files is not available on Novell NetWare networks or when Windows 2000 is running Terminal Services.

Files specified for offline use are stored, or cached, in a database on the hard disk drive of the local computer. If the network resource becomes unavailable, notification appears in the status area. Changes made to the file while offline are saved locally and then synchronized when the network resource is available.

Offline files and information about them are stored in a database in a hidden system folder (%systemroot%CSC). The database emulates the network resource while it is offline so that files are accessed as though the network resource is still available.

The Offline Files Folder is created when files are requested offline and provides a view of the files stored in the database.

CAUTION

---

If the network resource is online, renaming files in the Offline Files Folder takes effect immediately on the network resource.

To access Offline Files configuration options

In My Computer or Windows Explorer, click a folder.

On the Tools menu, click Folder Options.

Click the Offline Files tab.

NOTE

---

If there is already an Offline Files shortcut on your desktop, you can skip the following procedure and access the Offline Files Folder by double-clicking the desktop shortcut to Offline Files.

To access the Offline Files Folder

In My Computer of Windows Explorer, click a folder.

On the Tools menu, click Folder Options.

Click the Offline Files tab.

Click View Files.

Files are cached to the computer that requests them in one of two ways: automatic caching or manual caching. Automatic caching occurs when a specific file in a folder has been opened, but only if the network server indicates that the contents of the share should be automatically cached. Automatically cached files are marked as Temporarily Available Offline in the Offline Files Folder because they can be removed from the cache as the cache fills up. There is no guarantee that an automatically cached file will be available when offline. Automatic caching does not cache all the files in a folder.

Files are manually cached when a computer specifically requests, or pins, a particular file or folder on the network to be available offline. Files and folders are pinned by selecting the file or folder and clicking Make Available Offline on the File menu. Manually cached files are marked as Always available offline in the Offline Files Folder. The icon representing the file or folder updates to depict its offline status.

In Windows 2000 Professional, when a folder is shared, Manual Caching for Documents setting is enabled by default. To change the setting so that documents are automatically cached, right-click the folder, click Sharing, and then click Caching. In the Setting box, click Automatic Caching for Documents. You can also choose to disable caching.

NOTE

---

You can also manually pin files and folders that have been configured for automatic caching.

By default, the following files types cannot be cached:

*.SLM; *.MDB; *.LDB; *.MDW; *.MDE; *.PST; *.DB?

You can override the default settings by using the Files not cached Group Policy setting. Any file types you specify in the Group Policy setting override the default files types not usually cached. For example, if you specify that only *.txt files cannot be cached, all other file types become available for caching. .

The default cache size for automatically cached offline files is 10 percent of the total disk space of the hard disk drive. You can change the default (specify a value between 0 and 100 percent) on the Offline Files tab of the Folder Options dialog box (accessed by clicking Folder Options on the Tools menu). This setting does not affect the cache for manually cached files. You can store up to 2 gigabytes (GB) of manually cached files per computer if you have that much space available.

More About the Offline Files Database

The database containing information about Offline Files resides in the hidden system folder, or directory, called %systemroot%CSC. The name CSC refers to client side caching. The CSC directory contains all offline files requested by any user on the computer.

Files in the CSC directory are not encrypted, nor is encryption preserved, but file permissions and system permissions on the file are preserved. Therefore, a Microsoft® Word document created by Peter Tysver, given a password, and saved to a share on which only he has Full user rights, cannot be opened from the CSC directory by Renee Smith, because she has neither the share rights to open the file nor the password required to open the file in Microsoft Word.

To open or view the files in the CSC directory, you must log on as a member of the Administrators group. Because file encryption is not preserved, it is possible to log on as an administrator and to open files and view their content from the CSC directory by using a program such as Notepad. Users who share computers need to be aware that sensitive information can be viewed by anyone who is a member of the Administrators group.

NOTE

---

On a FAT file system or a FAT file system converted to NTFS, users might be able to read information that is cached in the %systemroot%CSC directory. This includes offline files requested by another user on the same computer.

It is very important not to move or delete files directly from the CSC directory. For more information about moving the cache folder and deleting files from the cache, see "Managing Offline Files" later in this chapter.

Reconnecting to the Network Resource

When a network share becomes available after being offline (for example, a server goes offline and is then brought back online, or a mobile computer is disconnected from the network and then reconnected), the network share is automatically available when three conditions are met:

No offline files from that network share are open on the user's computer.

No offline files from that network share have changes that need to be synchronized.

The network connection is not considered a slow link.

When all these conditions are satisfied and a user opens a file on the network share, the user is automatically working online on that network share. Any changes that a user makes is saved to the file on the network share and to the file that is cached in the Offline Files Folder. When any of these conditions are not satisfied and a user opens a file on the network share, the user is still working offline even though the network share is available. Any changes the user makes are saved only to the offline version of the file.

For more information about reconnecting over slow links or with mobile computers, see "Mobile Computing" in this book.

Synchronizing Files and Folders

It is important to understand how synchronization works between the locally cached version and the network resource version of a file. There are several ways to initiate synchronization, and, depending on the method you choose and the options you've enabled, either a full or quick synchronization of the files occurs.

When full synchronization occurs, the most current version of every cached network file is cached to the local drive. A quick synchronization is faster, but might not provide the most current version of every network file that has been made available offline. However, a quick synchronization does ensure that a complete version of every file is available.

There are several options that control how files are synchronized when the network resource becomes available. You can choose to synchronize:

Automatically at logon.

Automatically at logoff.

Manually at any time.

When the computer is idle for a specified amount of time.

Automatically at specified times.

To configure synchronization

Click Start, point to Programs, point to Accessories, and then click Synchronize.

Click Setup.

Use the Logon/Logoff, On Idle, and Scheduled tabs to configure options.

NOTE

---

Synchronization works only for the user who is currently logged on.

You can also start synchronization from Windows Explorer by clicking the Tools menu and then clicking Synchronize.

In order for synchronization to work, the network resources must be online or available for reconnection. Depending on how the synchronization is executed, offline changes might or might not be sent to the network resource and new versions of cached files might or might not be downloaded. In cases where a quick or partial synchronization occurs, data is copied from the network only to ensure availability while offline. When a full synchronization occurs, newer versions of files on the network are located and cached. Table 9.7 describes what kind of synchronization occurs when each method is used.

Table 9.7 Description of Synchronization Options and How Files are Cached

If the network resource version of a file and the locally cached version of the file are different, you can choose one of the following options in the Resolve file conflicts dialog box.

Keep both versions. Saves the version on my computer to the network as <filename>(username vX).doc, where filename is the name of the file, username is my user name, and X is the version number.

Keep only the version on my computer. Replaces the network version.

Keep only the network version. Replaces the version on my computer.

You are given the option to view each individual file. The date and time the files were saved is provided.

Using Offline Files on Mobile Computers

Offline files are particularly useful for mobile computer users. For more information about using offline files on mobile computers, such as synchronizing with a slow link and preventing synchronization when running on battery power, see "Mobile Computing" in this book.

Managing Offline Files

There are several different options you can use to delete files and folders no longer needed for offline use. It is important to understand how, where, and when to delete files, so that no changes are lost and files needed offline are still available.

Deleting Files and Folders

It is very important that nothing is deleted or moved directly from the %systemroot%CSC folder. When you need to remove all the files in the folder, see "Deleting All the Offline Files and Folders in the Cache" later in this chapter.

Remember, if you are working with files in the Offline Files Folder when the network resource is online, you are working directly on the network computer. When you rename or modify files from this location, the changes are immediately saved both in the Offline Files Folder and on the network resource.

There are two methods for safely removing offline files from the cache without affecting network files or folders. You can choose to delete files from the Offline Files Folder or click the Delete Files button on the Offline Files tab of the Folder Options dialog box (accessed by clicking Folder Options on the Tools menu).

Deleting Files from the Offline Files Folder

You can open the Offline Files Folder and delete files directly from the list of offline files. This allows you to delete individual files regardless of where they are located on the network or which folder they are contained in. When you delete a file this way, the file is removed from the cache regardless of whether it was manually cached (pinned) or whether it was automatically cached.

NOTE

---

Deleting files and folders from the cache does not delete the network copy of the file or folder.

If an offline folder is manually cached and you delete any or all offline files in the folder, the folder remains pinned and all files in the folder are cached the next time a full synchronization occurs.

To delete files from the cache using the Offline Files Folder

Click a folder, and on the Tools menu, click Folder Options.

On the Offline Files tab, click View Files.

Click the file you want to delete and on the File menu, click Delete.

Using the Delete Files Function

You can delete all files on a network share using the Delete Files button on the Offline Files tab of the Folder Options dialog box (accessed by clicking Folder Options on the Tools menu). This method allows you to delete every file in a network share and to distinguish between automatically cached files (temporarily available offline) and manually cached files (always available offline).

If you delete manually cached folders this way, the folders and the files in them are no longer pinned. To make those files or folders available offline again, you need to pin the files or folders. When you delete automatically cached files this way, you only need to open the files to make them temporarily available offline.

NOTE

---

Deleting files and folders from the cache does not delete the network copy of the file or folder.

To delete files from the cache on a network share

Click a shared network folder and then on the Tools menu, click Folder Options.

On the Offline Files tab, click Delete Files.

In the Confirm File Delete dialog box, select the shared folders containing the offline files you want to delete.

Click Delete only the temporary offline versions if you want to delete files that have been automatically cached. Click Delete both the temporary offline versions and the versions that are always available offline if you want to delete files that have been automatically cached and files that have been manually cached (pinned).

NOTE

---

Files are also deleted from the cache whenever an offline file is deleted through any usual user path, such as Windows Explorer, My Computer, the Run dialog box, or the Command Prompt. When users verify that they want to delete a file, the file is removed from the cache. This is not an effective way to clean up the cache because it also deletes files in the shared network folder.

Deleting All the Offline Files and Folders in the Cache

You can delete all the offline files stored in the %systemroot%CSC folder by using a process known as reinitializing the cache. This method deletes all offline files from the Offline Files Folder and resets the Offline Files database. If any files in the cache have changed and have not been synchronized with the network versions, the changes are lost when the cache is reinitialized. You must restart the computer after the cache is reinitialized.

To reinitialize the Offline Files cache

Click a folder, and then on the Tools menu, click Folder Options.

Click the Offline Files tab.

Press CTRL+SHIFT, and then click Delete Files.

Restart the computer.

CAUTION

---

You cannot undo the effects of reinitialization. After the cache is reinitialized all offline files are permanently removed from the computer.

Moving the Cache

The only way to safely move the hidden system folder (%systemroot%CSC) is by using the Offline Files Cache Mover (Cachemov.exe) tool available on the Windows 2000 Resource Kit companion CD. You can move the cache database to another location on a fixed disk only.

For more information about using the Offline Files Cache Mover tool, see Windows 2000 Resource Kit Tools Help on the Windows 2000 Resource Kit companion CD.

Policy Settings That Affect Offline Files

You can use a Group Policy setting or a combination of Group Policy settings to control the functionality of the Offline Files feature. For more information about using Group Policy with Windows 2000 Server, see "Group Policy" and "Introduction to Desktop Management" in the Distributed Systems Guide.

Table 9.8 lists some of the Group Policy settings that affect Offline Files and provides a brief description of each. Before you change a Group Policy setting, you should be familiar with using Group Policy and MMC snap-ins. To make changes to these settings, you must log on as a member of the Administrators group. You can find these Group Policy settings by using the Group Policy MMC snap-in and then following this path:

Local Computer PolicyUser ConfigurationAdministrative TemplatesNetworkOffline Files.

NOTE

---

These Group Policy settings appear in the User Configuration folders. If Group Policy settings are also configured in the Computer Configuration folders, the setting in Computer Configuration takes precedence over the setting in User Configuration.

Table 9.8 Group Policy Settings in User Configuration That Affect Offline Files

All the Group Policy settings that are available in the User Configuration folder are also available in the Computer Configuration folder. The Group Policy settings listed in Table 9.9 are only used as Computer Configuration settings. You can find the Computer Configuration Group Policy settings by using the Group Policy snap-in and then following this path:

Local Computer PolicyComputer ConfigurationAdministrative TemplatesNetworkOffline Files.

NOTE

---

If a Group Policy setting is configured in both locations, the Computer Configuration setting takes precedence.

Table 9.9 Group Policy Settings in Computer Configuration That Affect Offline Files

For additional information about Group Policy settings, including a more complete description of each setting, right-click the Group Policy setting, click Properties, and then click the Explain tab, or refer to the Group Policy Reference on the Microsoft® Windows® 2000 Resource Kit companion CD.