Volume Shadow Copy: An Overview :Volume Shadow Copy: An Overview


What Are Shadow Copies? :What Are Shadow Copies? Views the read-only contents of network folders as they existed at various points of time Use shadow copies to: Recover files that were accidentally deleted Recover files that were accidentally overwritten Allow version-checking while working on documents Shadow copies are available only on NTFS, not FAT volumes Is enabled on a per volume basis, not on specific shares Is not a replacement for regular backups When storage limits are reached (maximum of 64 shadow copies per volume) ,the oldest shadow copy is deleted and cannot be retrieved To change the storage volume, delete the shadow copies first.


How Shadow Copy Works :How Shadow Copy Works The shadow copy feature in Windows Server 2003 works by making a block-level copy of any changes that have occurred to files since the last shadow copy. Only the changes are copied, not the entire file. As a result, previous versions of files do not usually take up as much disk space as the current file, although the amount of disk space used for changes can vary, depending on the application that changed the file. 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 on the Windows Server 2003 CD, integrates seamlessly with the client PC and enables the user to view the previous version of the file.


Enabling Volume Shadow Copy :Enabling Volume Shadow Copy Right click on the volume that you wish to enable VSS for and select the Properties command from the resulting shortcut menu. Keep in mind that Volume Shadow Service (VSS) can only be enabled at the volume level. You can not control VSS at the disk level or at the folder or share level. At this point, you should see the volume’s properties sheet appear. Select the properties sheet’s Shadow Copies tab and you will be able to see which, if any, of the volumes currently have Shadow Copy enabled, as shown in Figure


Slide 5:Now, configure workstations so that users can access the shadow copy files. To do so, we must create a network share on the server that allows clients to access the server’s shared folder. From user’s workstation, access the shared folder from the server, open the file which was accidently deleted by user and wants to restore earlier version of the file. To do so, they would need to right click on the file and select the Properties command from the resulting menu. When the file’s properties sheet appears, the user must select the Previous Versions tab to reveal any previous versions of the file that may exist. Keep in mind that previous versions are not automatically created every time that the file changes, but rather every time that a scheduled (or manual) shadow copy runs and detects a version change. If there are previous versions available, they will be displayed as shown in Figure


Slide 6:To make the restoration, a user needs only to select the previous version and click Restore. The restored version will be in Read Only format though. The Read Only attribute is assigned as a way of protecting the file against unwanted changes. However, a user is free to remove this attribute (assuming that they have permissions) or to make a read / write copy of the file.


Conclusion :Conclusion Volume Shadow Copy Service do not eliminate the need to perform regular backups, nor do shadow copies provide protection from media failure. In addition, shadow copies are not permanent. As new shadow copies are taken, old shadow copies are purged when the size of all shadow copies reaches a configurable maximum, or when the number of shadow copies reaches 64, whichever is sooner. Therefore, shadow copies might not be present for as long as end users expect them to be. End user needs and expectations should be considered when shadow copies are configured


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