Novell Distributed File Services helps you modify the underlying physical organization of data on NSS volumes to maximize the use and performance of available storage resources.
DFS preserves the logical file organization from the user perspective by maintaining a Volume Location Database (VLDB) for all volumes in a DFS management context. When you move an NSS volume to a new volume in a different pool, the VLDB helps redirect queries to the new location.
When you split an NSS volume to relocate a directory’s data to a newly created NSS volume, DFS places a junction file in place of the directory at the source location. The junction contains a hint about the destination location of the data. When a user attempts to access the data, DFS uses that information to look up the location of the destination volume in the VLDB, then automatically redirects queries so that the session connection can be made transparently from the user’s point of view by going directly to the data. After the connection is made, the junction itself is no longer involved in the session.
Using junctions and the VLDB eliminates the user’s need to know the path to the physical location of the data. Not only does it decrease administration costs by allowing you to move a volume to a different server without making any announcements or needing to reeducate users, but it also simplifies the number of paths a user needs to remember if the data is spread among different volumes or servers.
For example, if John’s data is located on servers X, Y, and Z, you can create junctions on server X that point to all of his data on servers Y and Z. That way, John only needs to remember the path to server X, because with junctions, it appears as if the data is all located in one place.
DFS provides a solution to the common problem of storage volumes growing too big to back up within the desired or required time period. A too-large volume can be split into two (or more) volumes, and the resulting volumes backed up separately as required. You can split a volume at any directory to a new NSS volume without changing the logical path to files. You and your users can continue to use the logical paths when mapping network drives or creating login scripts. The physical location of data can change over time, and that change is completely transparent to the end user.
DFS can also provide a migration path for customers moving NSS volumes from NetWare® 6.5 or OES NetWare to OES 2 Linux. The task for DFS can be used to move file data on NSS volumes from NetWare servers to OES 2 Linux servers. This allows you to gradually move data to an OES 2 Linux environment, without committing to a turnkey change of operating environment. For an example, see Section 5.0, Migrating DFS from NetWare to OES 2 Linux.