Inodes and the Function of the Inode Cache File in Services for UNIX Server for NFS (234038)

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What is an Inode?

UNIX files do not actually reside in folders. A folder is really a file that contains references to other files. The folder holds two pieces of information about each file:

• Its file name.
• An inode number, which acts as a pointer to where the system can find the information it needs about this file.

File names are used by the system to locate a file and its inode number. This correspondence is called a link. To the system, the file is the inode number. Multiple file names can be used to refer to the same file by creating a link between an inode and each of the file names.

What is an Inode File?

The inode file caches pseudo-inode numbers for every file for which an NFS file handle is obtained in Server for NFS. Each drive letter in Server for NFS has a separate set of inode cache files. For example, the inode cache files for drive C are Drivec.nod and Drivec.ndx. The inode cache files for all drives are located by default in the C:\SFU\DiskShare folder.

The inode file is used because 32-byte NFS file handles are not large enough to store entire path names. Using an inode file enables reliable recovery in the event of resource loss on the part of the client, the server, or the network.

In large file systems, the inode file can become rather large. It can also become unusable, as a result of unpredictable events such as a power failure or a system crash. If the inode file becomes unusable or its size becomes a management problem because of a shortage of available free disk space, you may want to rebuild the inode file and restart the system.

You can use the Rebuild Inodes tool (on the Server Options tab in the Server for NFS Configuration tool) to start a rebuild of the inode file, which prompts the user to restart the server. Using the Rebuild Inodes tool instructs Server for NFS to remove and re-create its inode file as part of the next Server for NFS startup. Alternatively, if Server for NFS is stopped for some reason, an administrator can simply delete the problem inode cache file before restarting the server or the Server for NFS service.

NOTE: Removing or rebuilding the inode cache file and restarting Server for NFS requires any currently mounted clients to unmount and remount their shared resources. Symptoms may include error messages referring to a stale or invalid NFS file handle.