Tandberg Data Viking FS-1500 NFS Access to Shadow Copies, Tandberg DataShadow Copy Service, 4-17

Tandberg DataShadow Copy Service

__________________________________________________________________________________________________

4.7.2.NFS Access to Shadow Copies

UNIX users can independently access previous versions of files stored on NFS shares via the NFS client; no additional software is required. Server for NFS exposes each of a share's available shadow copies as a pseudo- subdirectory of the share. Each of these pseudo-subdirectories is displayed in exactly the same way as a regular subdirectory is displayed.

The name of each pseudo-subdirectory reflects the creation time of the shadow copy, using the format.@GMT-YYYY.MM.DD-HH:MM:SS. Note that, to prevent common tools from needlessly enumerating the pseudo- subdirectories, the name of each pseudo-subdirectory begins with the dot character, thus rendering it hidden.

The following example shows an NFS share named “NFSShare” with three shadow copies, taken on April 27, 28, and 29 of 2003 at 4 a.m.

NFSShare

@GMT-2003.04.27-04:00:00

@GMT-2003.04.28-04:00:00

@GMT-2003.04.29-04:00:00

Access to NFS shadow copy pseudo-subdirectories is governed by normal access-control mechanisms using the permissions stored in the file system. Users can access only those shadow copies to which they have read access at the time the shadow copy is taken. To prevent users from modifying shadow copies, all pseudo-subdirectories are marked read-only, regardless of the user's ownership or access rights, or the permissions set on the original files.

Server for NFS periodically polls the system for the arrival or removal of shadow copies and updates the root directory view accordingly. Clients then capture the updated view the next time they issue a directory read on the root of the share.

4-17 Tandberg Viking Series Storage Server Administration Manual