Integrated File System Introduction

 

Use NFS file systems through the integrated file system interface

The Network File System is accessible through the integrated file system interface and has the following considerations and limitations.

Characteristics of the network file system

The characteristics of any file system mounted through NFS are dependent upon the type of file system that was mounted from the server. It is important to realize that requests performed on what appears to be a local directory or file system are really operating on the server through the NFS connection.

This client/server relationship can be confusing. Consider, for example, that you mounted the QDLS file system from the server on top of a branch of the "root" (/) directory of your client. Although the mounted file system would appear to be an extension of the local directory, it would actually function and perform as the QDLS file system.

Realizing this relationship for file systems mounted through NFS is important for processing requests locally and through the server connection. Just because a command processes correctly on the local level does not mean that it will work on the directory mounted from the server. Each directory mounted on the client will have the properties and characteristics of the server file system.

Variations of servers and clients in the network file system

There are three major possibilities for client/server connections that can affect how the Network File System will function and what its characteristics will be:

  1. The user mounts a file system from an iSeries server on a client.
  2. The user mounts a file system from a UNIX server on a client.
  3. The user mounts a file system from a non-iSeries, non-UNIX server on a client.

In the first scenario, the mounted file system will behave on the client similarly to how it behaves on the iSeries server. However, both the characteristics of the Network File System and the file system being served need to be taken into account. For example, if you mount the QDLS file system from the server to the client, it will have the characteristics and limitations of the QDLS file system. For example, in the QDLS file system, pathname components are limited to 8 characters plus a 3 character extension. However, the mounted file system will also have NFS characteristics and limitations. For example, you can not use the CHGAUD command to change the auditing value of an NFS object.

In the second scenario, it is important to realize that any file system mounted from a UNIX server will behave most similar to the iSeries server QOpenSys file system. To find out more about the QOpenSys file system, please see Open systems file system (QOpenSys).

In the third scenario, you will need to review the documentation for the file system associated with the server's operating system.

Links in the network file system

Generally, multiple hard links to the same object are allowed in the Network File System. Symbolic links are fully supported. A symbolic link can be used to link from a Network File System to an object in another file system. The capabilities for multiple hard links and symbolic links are completely dependent on the file system that is being mounted with NFS.

See Link for a description of links.

Use integrated file system commands in the network file system

All of the commands that are listed in Perform operations using CL commands and the displays that are described in Perform operations using iSeries menus and displays can operate on the Network File System, except for the following:

There are some CL commands that are specific to the Network File System and other mounted file systems in general. However, it may not be safe to use these commands in a multi-thread capable process. The following table describes these commands. For a complete description of commands and displays that are related specifically to the Network File System, see OS/400 Network File System Support link to PDF.

Table 7. Network File System CL Commands

Command Description
ADDMFS Add Mounted File System Places exported, remote server file systems over local client directories.
CHGNFSEXP Change Network File System Export Adds or removes directory trees to the export table of file systems that are exported to Network File System clients.
DSPMFSINF Display Mounted File System Information Displays information about a mounted file system.
ENDNFSSVR End Network File System Server Ends one or all of the Network File System daemons on the server.
EXPORTFS Export a file system Adds or removes directory trees to the export table of file systems that are exported to Network File System clients.
MOUNT Mount a file system Places exported, remote server file systems over local client directories. This command is an alias for the ADDMFS command.
RLSIFSLCK Release Integrated File System Locks Releases all Network File System byte-range locks held by a client or on an object.
RMVMFS Remove Mounted File System Removes exported, remote server file systems from the local client namespace.
STRNFSSVR Start Network File System Server Starts one or all of the Network File System daemons on the server.
UNMOUNT Unmount a file system Removes exported, remote server file systems from the local client namespace. This command is an alias for the RMVMFS command.
A Network File System must be mounted before any commands can be used on it.

Use integrated file system APIs in the network file system

All of the C language functions that are listed in Perform operations using APIs can operate on the network file system, except for the following:

For a complete description of the C language functions that are related specifically to the Network File System, see OS/400 Network File System Support link to PDF.

A Network File System must be mounted before any APIs can be used on it.

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