Microsoft Windows XP Professional Resource Kit 2003
ISBN: N/A
EAN: N/A
EAN: N/A
Year: 2005
Pages: 338
Pages: 338
By using Offline Files, users can disconnect from the network and work as if still connected. When the computer is offline, the files and folders appear in the same directory that they appear in online as if they are still in the same location on the network. This allows the user working offline to edit files. The next time the user connects to the network, the offline changes are synchronized with the network share. Any changes that were made while the user was working offline are updated to the network.
Offline Files is especially useful for mobile users with portable computers because they can use it to access their files when they are not connected to the network. Thus users can always open, update, and work with current versions of network files when they are not connected to the network.
Offline Files stores the data in the computer s cache to make network files available offline. The cache is a portion of disk space that a computer accesses when it is not connected to the network. The view of shared network items that you make available offline is the same as the view online, even if users lose a connection to the network or remove a portable computer from the docking station. Users have the same access permissions to those files and folders that they have when they are connected to the network.
If two users on the network make changes to the same file, they can save their own version of the file to the network, keep the other user s version, or save both.
You can make shared files or folders available for offline use from any computer that shares files by using server message block (SMB) based file and printer sharing, which includes any computer running Windows 2000, Windows 95, Windows 98, or Windows NT 4.0. The Offline Files feature is not available on Novell NetWare networks. When configuring a shared folder, you have the option to choose whether all the files in the folder are automatically available offline, or whether a user must explicitly mark a file to be available offline.
Offline Files is a stand-alone technology, which means that you do not need to pair it with Folder Redirection and set up and configure network shares. However, pairing the two technologies works well. By default, any folder that is redirected is available offline as well.
In Windows XP Professional all the files in a redirected folder, including subfolders, are automatically made available offline. You can disable automatic caching of redirected folders by using the Group Policy setting Do not automatically make redirected folders available offline, under User Configuration\Administrative Templates\Network\ Offline Files.
| Note | In Windows 2000, redirected folders are not automatically made available offline. To make folders available offline, administrators use the policy setting Administratively assigned offline files, or the users manually make all files available offline. |
Before you can have offline access to the files on a shared network folder, you must specify how the files in the folder are stored in a cache on the client computer in this case, the user s portable computer. For non-executable files, such as word processing documents, spreadsheets, and bitmaps, there are two options for storing files: automatic caching, and manual caching.
Automatic caching makes a file available offline by creating a locally stored copy of the file when a user opens the file on a portable computer. Automatically stored files might not always be available in the cache because Offline Files might remove, or purge, them when the cache becomes full. Offline Files will purge files based on frequency of use. Automatic caching is most useful when you have an unreliable or unpredictable network connection. For example, if a user is working on an automatically stored file, and the portable computer is disconnected from the network, the user can continue working on the file without interruption. To make a file available offline at all times, you can use My Computer to mark the file as Always available offline. For more information about making files available offline, see Managing Files and Folders in this book.
Manual caching makes a file or a folder available offline, but only when it is pinned, that is, manually marked on the user s computer. A manually stored file or folder that is not pinned on the user s computer is not available offline. Manual caching is useful for users who need access to a file or folder all of the time or for users who need access to entire folders, especially folders that contain documents created by or modified by other users. For example, manual caching works well for users who frequently use a portable computer away from the office without a network connection but still need access to many files on the network. In this case, you can manually pin folders on the user s portable computer to make those folders available to the user when away from the office. Automatic caching is not ideal in this case because the files in the network folder are not locally stored unless the portable computer user opens each file while the portable computer is connected to the network share.
To configure automatic or manual caching on a shared network folder
Right-click the shared folder that you want to configure, click Properties, and then click the Sharing tab.
In the Properties dialog box, click Caching.
In the Setting box, select a type of storing.
On the Setting box menu, you can also choose Automatic caching of programs and documents, which is useful if a user runs programs from the network. This option stores a copy of a network program on the user s hard disk so that the user can run the program offline. However, users of portable computers must be careful when using this feature because only the program files that are executed are stored on the local computer. For example, if you run Microsoft Word from a network share, but you do not use the spelling checker, the spelling checker is not stored. If you then run Word offline and try to run the spelling checker, the tool is not available. To avoid this problem, you can load all programs and associated tools locally on a portable computer and not use the Automatic caching of programs and documents option.
Synchronization ensures that any changes made to offline files and folders are propagated back to the network and that any changes that have occurred on the network are propagated to the user s computer. Some synchronization features and options relate specifically to portable computers. For more information about all synchronization options, see Managing Files and Folders in this book.
In order for synchronization to occur, the hard disk on a user s portable computer must be turned on so that files can be copied from the network to the local cache, and files in the local cache can be copied to the network. Synchronization might not be an optimum use of power for a portable computer running on battery power. However, certain options allow you to set synchronization to occur when a computer runs on battery power. You can also use Group Policy to synchronize all offline files before logging off.
To ensure that all offline files are fully synchronized, you must enable the Local Computer Policy setting, Synchronize all offline files before logging off, in the Administrative Templates\Network\Offline Files folder. When this Group Policy setting is enabled, all files in the user s redirected folder are available when the user is working offline. If this setting is not enabled, the system only performs a quick synchronization, and as a result only files that were used recently are cached. This setting appears in the Computer Configuration and User Configuration folders. If both settings are configured, the setting in Computer Configuration takes precedence over the setting in User Configuration.
By default, offline files are not synchronized when a computer is in an idle state and using battery power. This is because portable computers rely on a low-power idle state to conserve battery power, and you might not want to use battery power to synchronize files. You can change the default so that synchronization occurs when the computer is on idle and running on battery power.
To enable synchronization when a computer running on battery power is idle
In All Programs, point to Accessories, click Synchronize, and then click Setup.
In the Synchronization Settings dialog box, click the On Idle tab, and then click Advanced.
In the Idle Settings dialog box, clear the Prevent synchronization when my computer is running on battery power check box.
You can schedule synchronization to occur on specific days and at specific times. Because a scheduled synchronization is often a low-priority task that consumes power, Windows XP Professional allows you to prevent scheduled synchronization from occurring when a computer is running on battery power.
To prevent scheduled synchronization from occurring when a computer is running on battery power
In All Programs, point to Accessories, click Synchronize, and then click Setup.
In the Synchronization Settings dialog box, click the Scheduled tab.
Click a scheduled task, and then click Edit.
On the Settings tab, under Power Management, select the Don t start the task if the computer is running on batteries check box.
If a scheduled synchronization is in progress, and a portable computer is switched from alternating current to battery power, you can have Windows XP Professional cancel synchronization. This might occur if scheduled synchronization starts on a docked portable computer that is using a wireless network connection, and the user performs a hot undock.
To stop scheduled synchronization when the computer is running on battery power
In All Programs, point to Accessories, and then click Synchronize.
In the Items to Synchronize dialog box, click Setup.
Click the Scheduled tab.
Click a scheduled task, and then click Edit.
On the Settings tab, under Power Management, select the Stop the task if battery mode begins check box.
If a computer is not connected to a network when a synchronization is scheduled to start, you can configure Windows XP Professional to connect so that synchronization can occur. In this case, Windows attempts to connect to the designated network, detects that the computer is not connected to the network, and then informs the user that the network is not available. By default, Windows does not connect if there is no network connection at the time of synchronization. Although you might use this option for portable computer users who are normally connected to the network, you might not want to enable it for users who frequently use the portable computer while it is disconnected from the network.
To enable automatic connection for scheduled synchronization
In All Programs, point to Accessories, click Synchronize, and then click Setup.
On the Scheduled tab, under Current synchronization tasks, click a scheduled task, and then click Edit.
On the Synchronization Items tab, select If my computer is not connected when this scheduled synchronization begins, automatically connect for me.
Windows does not provide a system wide definition or threshold for a slow link. Instead, it allows every system component to define a slow link according to its own capabilities and requirements. For example, one component might define a slow link as 28.8 kilobits per second (Kbps) while another might define it as 56 Kbps. For Offline Files and synchronization in a Windows 2000 Active Directory environment, you can use Group Policy settings to define file synchronization behavior over a slow link. The default slow link threshold value is 64 Kbps.
A slow-link connection affects synchronization by preventing the following:
Automatic transition of shared network folders from an offline to an online state.
The copying of newly added files from the network share to the user s computer.
In Windows XP Professional and Windows 2000 Server you can use the Configure slow link Group Policy setting located in Computer Configuration\Administrative Templates\ Network\ Offline Files to define the threshold value at which Offline Files considers a network connection to be slow.
For more information about the Group Policy settings associated with Offline Files, see Managing Files and Folders in this book.
After a network share has been offline to a user for example, if a server goes offline and is then brought back online, or a user undocks a portable computer and then docks it the share becomes available online for the user if the following three conditions are true:
No offline files from that network share are open on the user s computer.
None of the offline files from that network share have changes that need to be synchronized.
The network connection is not considered a slow link.
When these conditions are true, and a user opens a file on the network share, the user is working online on that network share. Any changes that the user makes are saved to both the file on the network share and the file stored in the Offline Files folder. If any one of the conditions is not true, 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 that the user makes are saved only to the offline version of the file.
When a user first connects to a network over a slow-link connection, the user is only working offline on any shared network folders even though the online folders are available. To start working online with a shared network folder, the user must synchronize the shared network folder. Synchronization shifts the folder to an online state and pushes any offline files that have changed to the shared network folder. To pull files from the shared network folder to the Offline Files folder, the user must perform a second synchronization, which pulls files that have changed from the network share to the Offline Files folder.
| Note | When you use a slow-link connection, a second synchronization does not pull newly created files from the network share to the Offline Files folder. To make new files on the network share available offline during a slow-link connection, you must pin the files. |
Slow-link connections can prevent a network share from coming online even though the network share is available. Although you can bring the network share online by synchronizing it, this method might not be ideal. For example, when a user s portable computer is disconnected from the network, and the user requires access to a file on a shared network folder that has been made available offline, a file to which the user has made several changes offline might not be ready to synchronize with the network share. Or, the user might be in a hurry and does not want to take the time to synchronize files. The user wants only to connect to the network, get the new file from the network share, and then log off. Windows XP Professional provides a way for the user to make a folder available online without synchronizing offline files.
To make a folder available online without synchronizing offline files
In the notification area, click the Offline Files icon to open the Offline Files Status dialog box.
Select Work online without synchronizing changes.
| Note | The Offline Files icon appears in the notification area when users are working offline. |
Windows XP Professional provides several methods of protection for offline files. The Offline Files folder, including the Offline Files database and the stored offline files, is secured against unauthorized access by administrator permissions. Additionally, the same user rights that protect their network counterparts protect offline files and folders. Windows XP Professional also supports encryption of offline files.
Offline files are stored (cached) in the Offline Files folder. Each computer has only one Offline Files folder, even if the computer is shared by multiple users, and all offline files are stored in this folder. By default, this folder is protected by administrator permissions so that unauthorized users cannot view the contents. However, these permissions are only applied to the folder if the folder is located on a drive that is formatted to use NTFS. Windows XP Professional notifies you of this limitation when you first cache an offline file on a FAT or FAT32 drive. For more information about file system security, see File Systems in this book.
In addition to the protection afforded by the permissions on the actual Offline Files folder, offline files and folders retain the permissions set for them on the network share. This type of security is important if multiple users share a single computer. For example, if a user creates a file on a network share, changes its permissions so that only that user has access to the file, and then makes the file available offline, another user who tries to open the offline version of the file on the user s computer is denied access, just as if the second user tried to open the file directly on the network share.
This type of security is applied to offline files regardless of the formatting of the user s hard disk. Thus, if you set permissions on a file on a network share that is formatted to use NTFS, and you make that file available offline on a computer that has a FAT or FAT32 drive, the permissions carry over to the offline version of the file, even though the drive is formatted to use FAT or FAT32.
You can secure data on portable computers by encrypting the offline files. Windows XP Professional provides Encrypting File System (EFS) support for Offline Files. The local cache of Offline Files can be encrypted if the cache directory resides on an NTFS volume. When the cache is encrypted, the local copy of a cached file is automatically encrypted.
To encrypt offline files
In Folder Options, click the Offline Files tab.
Select the Encrypt Offline files to secure data check box.
You can also use Group Policy to apply this option to groups of users. In the Group Policy snap-in, go to Computer Configuration\Administrative Templates\Network\ Offline Files.
Offline files stored on local hard disks are secured by EFS, however, the files are encrypted in the system context and the encryption applies to all users of the local computer. If both the local computer and the remote computer where the files are stored are encrypted, files are encrypted at all times. If the local computer is encrypted, but the remote location of the files is not, the files are encrypted while they are stored locally.
If the remote location is encrypted and the local computer is not, however, you are warned when you try to make a file available offline that it will not be encrypted on the local computer. You can override the default and make the files available; when you attempt to synchronize the files, the local copy will be deleted.
Portable computer users who frequently work offline might accumulate hundreds of files in the Offline Files folder on their hard disk. Because many of these files might be out-of-date, rarely used, or no longer needed offline, you might want to delete them from the Offline Files folder (the cache) to maximize the available disk space. Users might also want to delete files in the Offline Files folder if a network share has been deleted or is no longer available. In addition to deleting individual files, you can reinitialize the Offline Files cache, which deletes the entire contents of the Offline Files folder and resets the Offline Files database. Reinitializing the Offline Files cache is useful when you transfer a computer to a new user or when a user has been working offline with sensitive or proprietary documents and you want to ensure that they are no longer available offline or that they are not in the cache.
You can safely remove offline files from the cache without affecting network files or folders by deleting files from the Offline Files folder or by reinitializing the cache. Do not delete or move any files directly from the systemroot\CSC folder. For more information about deleting offline files from cache without affecting network files or folders, see Managing Files and Folders in this book.