Services for UNIX

Client for NFS

Microsoft Client for NFS (Services for UNIX Version 1.0) allows a computer running Windows NT to act as an NFS client and access directories and files located on a server running NFS. The NFS client mounts a directory on the NFS server. The remote access is transparent to the user.

Client for NFS supports the following features:

Access to Remote Files Exported directories and files from an NFS server can be mounted locally by an NFS client. A user's access to a directory or file is determined by that file system's export options and by the permissions applicable to the file itself.

Mount Options Under UNIX, the user or system administrator connects to a remote file system by issuing the mount command. This command supports various options, depending on the implementation of UNIX. Services for UNIX supports mount options that determine the following:

Buffer size, which determines the number of packets sent in a read or write request.
Type of mount, hard or soft. Hard mounts retry system calls indefinitely when a server stops responding or fails; soft mounts do not. File systems that are exported with read/write access or that contain executable files need to be hard-mounted to guarantee data integrity.
Time an RPC call waits for a response from the server before timing out.
Number of times an RPC call is resent if the NFS server does not respond (soft mount only).
File locking, which allows a user to have exclusive access to a file. NFS's file locking works best if all NFS clients have file locking enabled.
Caching of read data on the NFS client, which reduces the number of calls to the NFS server.
Caching of write data on the NFS server, to reduce the overhead of small write operations.

NFS Authentication Options Three methods of authentication are supported:

Anonymous UID. Identifier for users without a valid login and password on the NFS server.
Standard UNIX Authentication using an NIS server. Authentication method for users with a valid login and password stored on an NIS server.
PCNFSD Authentication. Authentication method that uses the pcnfsd daemon to authenticate the login and password for NFS client computers.

Resolution of Symbolic Links Services for UNIX permits the renaming and deletion of a symbolic link. For Client for NFS to find the target of a symbolic link that is located on a file system different from the file system that is currently mounted, an entry must exist in a special configuration file that maps the remote file system to that file system's server name or share name. If no entry is found in the configuration file, Client for NFS assumes that the target file is on the same computer.

Mapping of NFS Directories to Local Drives Mounted NFS directories can be mapped to a local Windows drive, enabling a user to browse the directory by using Windows Explorer.

Setting of File Access Permissions Client for NFS supports changes to UNIX permissions on remote files.

Resolution of File Name Case Since file naming in UNIX is case sensitive and Windows preserves case but ignores it, Services for UNIX provides options to resolve file naming conflicts.

Troubleshooting Tools Services for UNIX provides the showmount and rpcinfo commands for use in diagnosing NFS conflicts. These commands are discussed in this chapter.