If you're a Microsoft small business running either Windows 7 or Vista computers, the operating system's built-in file synchronization feature can save you a lot of time and aggravation. Here’s the situation:
You’re in the office with your laptop, working with documents that are stored somewhere on a company server. But you have to be out the door soon and haven’t finished your work, so you’ll need to have access to those files from the road -- places where a link to your office network won’t be readily available.
 The first time you enable offline access for a folder, it may take some time to copy all of the files over to your computer. (Click for larger image). |
In this scenario, you could copy the file(s) from the network to your laptop, work on them from the road, and then copy them back to the server location the next time you’re in the office, taking care to check that your version of a given file is newer than the one on the network.
You could do that, or better yet, save yourself the hassle by using Windows 7’s Offline Files feature to automatically handle the file transfer and synchronization chores for you. With Offline Files, network files will stay with you even when you’re not on the network, and when you do connect again, any updates you made to the files will be synced up with the originals.
The Offline Files feature is available in Windows 7 Professional, Ultimate, and Enterprise, as well as Vista Business, Ultimate and Enterprise. It's also available in Windows XP, but the configuration process is different than Vista or Windows 7.
You can use Offline files with a single important file, a bunch of individual files stored in different locations on the network, or on an entire folder or mapped network drive. Also, the network location that houses the files need not necessarily be a Windows-based server; in some cases it can also be a garden-variety NAS device, or even a shared folder on another PC, as on a peer-to-peer network.
However, when using a non-Windows NAS device, Offline files may work best when used for an individual’s personal data rather than with shared files or folders that are frequently modified by many different people (for more on this, see the Sync Center: File Synchronization section below).
Using Windows Offline Files
To make a network file or folder available offline, right-click it and select the Always available offline option. Depending on the speed of the network connection and how much data you’ve selected, it could take some time for all of the data to be copied over to your system, but you can close the notification window and work normally while the transfer is taking place.
After a file or folder has been designated for offline access, its icon in Windows Explorer will sport the green “Sync Center” label, and if you check the Details pane for the item (at the bottom of the window), you’ll see its Offline availability listed as Always available.
Now, let’s say you leave the office and open up your laptop on the train, at your kitchen table, etc. Your files will still be there and appear as if they’re coming from the office network, except you’ll actually be viewing the local copies instead. (You can tell whether or not you’re connected by consulting the aforementioned Details pane for the file or folder to see whether Offline status is listed as Online or Offline.) While working offline you can browse, open and edit files, just as you do in the office, although there may be a slight delay when initially accessing a file or folder as Windows determines the status of your network connection.
When your link to the network is restored, whether it’s because you’ve returned to the office or connected remotely (e.g. via a VPN), your laptop’s Offline Files are automatically checked against the network versions. If your offline files have changed but the originals on the network haven’t, your versions are copied back over to the network. (Similarly, if you delete the offline version of a file, it’s counterpart on the server will be deleted as well.)
Conversely, if the network version of an offline file has changed but yours hasn’t, the network’s version is transferred to your system to keep both copies in sync. (If neither version of a file has changed, no action is taken since they’re already in sync.) This synchronization process will happen in the background and generally not require any input from you.
But what happens your version of a file AND the network version have both changed (i.e. someone else modified the network copy while you were offline, or you did, from another computer)? That’s called a sync conflict, and it does require user input, which brings us to our next topic.
Sync Center: File Synchronization
After you set up Offline Files you’ll find a Sync Center icon in the Windows notification area; it can be used to check sync status, to sync manually and to resolve sync conflicts. (In Windows 7 the Sync Center icon will be hidden by default -- to see it, click the up arrow and then either use the icon directly or drag it down to your notification area for more convenient access.)
If any of your files fail to synchronize, the Sync Center icon will display the telltale yellow “!” symbol; right-click the icon and select View Conflicts to see which file(s) haven’t synched. When you highlight a conflicting file (or files) and click Resolve, you’ll be able to compare the two file versions -- by date and time, by size or by opening them to examine the contents -- to decide which one to sync with.
 If there is a sync conflict, you can decide which file to keep based on date, size or content. (Click for larger image). |
A sync conflict occurs when Offline Files won’t sync without user intervention to settle a file discrepancy, but sync errors occur when Offine Files can’t synchronize for some reason, usually due to a problem on the server you’re trying to sync with.
Sync errors can have a variety of causes, but one particular error -- "The process cannot access the file because it is being used by another process" -- is common when trying to sync files that are stored on non-Windows NAS devices and have been recently been opened by another Vista or Windows 7 system. This type of sync error is often the result of a performance-enhancing file access technique called opportunistic locking used by Vista and Windows 7 (but not XP) systems, which allows them to can lock access -- and thus prevent modifications -- to files that have been recently opened (even though they may no longer be open).
Opportunistic locking is often not enabled on non-Windows NAS devices, most of which use the SAMBA file sharing protocol to communicate with Windows systems. While some NAS devices will let you turn on the feature via an administrative control panel, many consumer and small office NAS products don’t.
If you encounter this file-locking problem and can’t find a way to turn on opportunistic locking on the NAS device, upgrading the firmware and/or making the Registry modification to the Vista/Win7 systems that access the file or folder in question may help. If not, you might want to consider synching via a third-party utility like Microsoft’s own (free) SyncToy 2.1. You shouldn’t run into the problem when you’re the only one accessing a folder, and you’re only doing so from a single system.
It’s important that company files be stored centrally on the network for backup purposes. But with Offline Files, you don’t need to be bound to a network connection to access important data, which makes it much easier to get work done outside the office.
Joseph Moran is a veteran technology writer and co-author of Getting StartED with Windows 7, from Friends of ED.
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This article was originally published on March 30, 2010
