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.
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.