Professor Windows - April 2004
Love at First Snapshot (Shadow Copies on Windows Server 2003)
Professor Windows and Erez Paz, Rapid Adoption Manager, Microsoft Israel
Paul Luber, Program Manager, Microsoft Corporation
As a former system administrator, one of the things I hated most was to get a telephone call from one of my users telling me that their most precious document was lost and need me to come to the rescue. That meant that I had to go to my server room, search for my latest backup tape and try to recover their document(s). If we were lucky, the backup tape was found, and if we were very lucky the document was restored successfully.
Windows Server 2003 includes a new feature called Shadow Copies that can ease your pain quite significantly in the above scenario. Shadow Copies are a free service that comes with Windows Server 2003 and helps you ease the recovery of old versions of user files when they're accidentally deleted, corrupt, or edited.
The benefits of Shadow Copies are as follows:
- Empower users to recover their own file quickly and easily.
- Eliminate the need to rebuild the file all over again.
- Decreasing the IT department / helpdesk calls.
- Lower the cost and time spend recovering lost data from backup tapes.
Why Should We Consider It?
When users lose their data by deleting a file or using Save instead of Save As when making another version of their document, we may overlook the impact to our business. Studies show that 34 percent of data loss is due to human error. The two main options a user has at this point are:
- Calling the IT department asking them to restore files from a backup
- Rebuild the document all over again.
In most cases, users will build the document all over again. Does it mean that the IT department is inefficient? Not really, it just means that the user prefers to rebuild the document rather than wait and do nothing until the IT department restores the document. Both of the options are a waste of valuable time. This is where Shadow Copies comes into the picture. With Shadow Copies we can give our users the power to restore their documents or files without calling the IT department.
By using Shadow Copies, a Windows Server 2003-based file server can efficiently and transparently maintain a set of previous versions of all files on the selected volumes. End users access the file or folder by using a separate client add-on program, which enables them to view the file in Windows Explorer. The client program, which is included with the Windows Server 2003 product compact disc, integrates seamlessly with the client PC and enables the user to view the previous version of the file.
I should make a clear and important note right here, right now:
Shadow Copies did not come to replace any backup mechanism that you have in your organization, but simply helps simplify the restore process.
Using Shadow Copies
Shadow Copies come as part of the new feature set of Windows Server 2003. When you enable Shadow Copies for the first time it will take a snapshot of your volume in your server. The snapshot will collect only the changes in you files and not the files themselves - saving your disk space. Your users will be able to access the shares on the server and return to their previous versions from their desktop.
On the server, simply open My Computer, right-click on a selected volume, choose Properties, and select the Shadow Copies tab. Choose on the Enable button, which will create a snapshot of all your shares on that volume and you're done!
To enable your users to restore a copy of a lost document, you need to install on their work station the Shadow Copies client. You can do it automatically through group policy objects (it comes as a MSI) or by management products such as Systems Management Server. If your users want to restore a previous version of their file, they can enter the share on the server, right-click on the file and select Properties. They will discover a new tab named Previous Versions. Choosing it would reveal a list of all the previous versions of that file. They can select from the list - arranged by date, and click on one of three buttons: View (to view the file that they want to restore); Copy (to copy it to another folder); Restore (to overwrite the original file).
Figure 1 The previous version tab on the file properties.
Both users and the IT department use Shadow Copies the same way to recover data losses. The most common scenarios for data loss are accidental file deletion, accidental file overwrite, file corruption, and to find an archived version of a file. In all these scenarios, the end user can view the content of a shared folder as they existed at a specific point in time, and recover those files by themselves. This eliminates administrators having to restore accidentally deleted or overwritten files.
Implementing Shadow Copies – Important Points and Tips
There are four key decisions that must be taken before implementing Shadow Copies. They are:
- Source files
- Disk space
- Location of copies
Using the Shadow Copies without referring to those key decisions will impede the proper setup and subsequent use of the service.
Source files – Shadow Copies are taken from a complete volume and work best with user files such as spreadsheets, documents, presentation, etc. It work with compress or encrypt files and retain whatever permissions were set on the file. Do not use Shadow Copies to provide access to previous version of application or e-mail databases.
Keep in mind that Shadow Copies work only on NTFS volumes.
Disk space – When you enable Shadow Copies on a volume, it uses 10 percent of it by default (you can change it through the Settings tab). If this limit is reached, Shadow Copies will overwrite the oldest version. The most important thing to consider is that the amount of disk space Shadow Copies will use depends on how frequently the users change their files rather than how much data is being stored.
Location of copies – When a schedule snapshot starts the burst disk IO will reduce the performance of the disk. Using a separated volume on separated disks provides better performance and is recommended.
Schedule – It is important to schedule the creation of Shadow Copies to suit the organization's needs. By default, Windows Server 2003 creates Shadow Copies at 0700-hours and 1200-hours, Monday through Friday. The more frequently Shadow Copies are created, the more likely that end users will get the version that they want. However, the maximum limit of Shadow Copies is 64 per volume and the more Shadow Copies are created, the more disk space the Shadow Copies can consume, especially if files change frequently.
It is best that you install the Shadow Copies client only to users that need it or have lost data and need to recover it.
Note that Shadow Copies have a limit of 64 copies only. Don't schedule creation of Shadow Copies too frequently.
Another good practice is to avoid using Shadow Copies on the C drive or any other drive that accesses the paging file.
You should also pay attention to a known issue that is resolved in Version 5.2.01 of the Shadow Copy Client. For more details, see:
Finally, the download location for the Shadow Copies Client for Windows 2000 and above is available at: http://www.microsoft.com/downloads/details.aspx?amp;amp;amp;displaylang=en&familyid=e382358f-33c3-4de7-acd8-a33ac92d295e&displaylang=en.
May the source be with you.
- Shadow Copies of Shared Folders: Frequently Asked Questions
- An animated demonstration of Volume Shadow Copy Service
- Shadow Copies Client Download
- Windows Server 2003 Deployment Kit and the Microsoft Windows Server 2003 Resource Kit
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