Distributed filesystems

Files can be shared across a network when a server exports directories to be shared and clients mount the directories to access the files in them. Filesharing under the SCO OpenServer Desktop and Enterprise systems is provided by:

NFS

The SCO Network File System (NFS) is a product that enables you to export and mount filesystems across a network. This allows users on a local machine, or client, to access specified files and directories from a remote machine, or server, without the time-consuming process of remote logins or machine-to-machine file copying.

In addition to exporting native UNIX filesystems, SCO NFS can export DOS filesystems.

automount

automount allows remote NFS filesystems to be mounted automatically and transparently. Whenever a user on a client machine running automount invokes a command that accesses a remote file or directory (such as when opening a file with an editor), the hierarchy to which that file or directory belongs is mounted and remains mounted for as long as it is needed. No mounting is done at boot time, reducing significantly the time needed to boot up.

NLM

The Network Lock Manager (NLM) network service consists of a loadable device driver and a set of daemons that permit both advisory and mandatory file and record locking on local files. Only advisory file and record locking are supported on remote SCO NFS files. The NLM package includes the SCO NFS Status Monitor, which works in conjunction with the NLM to determine when a remote host has recovered after a crash.

REX

The Remote Execution (REX) service is a remote command service. It allows users to export their user environments to remote servers. These servers execute commands that can access files in the user's current directory and allow the execution of interactive processes such as full-screen editors. REX consists of a set of utilities, commands, and library functions.

Configuring NFS

To configure file sharing using NFS, you must:

• establish physical connections.

• configure networking drivers, TCP/IP, and NFS together using the Network Configuration Manager -- see ``Configuring network connections''.

• configure NIS (Network Information Service) if desired -- see ``Configuring the Network Information Service (NIS)''.

• configure NFS by:

  • exporting mountable directories from a server using the SCOadmin Filesystem Manager interface.

  • starting NFS daemons on the client and server if this was not done when SCO OpenServer was installed.

Administering NFS

There are five ways to remote mount exported filesystems:

• by the system administrator's using the SCOadmin Filesystem Manager interface

• by default when the system goes into multi-user mode through entries in /etc/default/filesys

• manually as root using the mount command

• automatically by automount whenever an exported filesystem is referenced by a user; see ``Configuring the NFS automounter''

• explicitly by a user using the mnt(C) command through entries in /etc/default/filesys (automount is recommended instead of this method)

NIS can be used in conjunction with automount to ensure that each NIS system can automatically mount filesystems from the same set of NFS servers. In this case, automount maps are maintained on the NIS master server and distributed as NIS maps to other NIS systems. Local variations can be made to NIS-distributed automount maps. See ``Managing automount with NIS''.

Administering NFS entails the regular execution of common tasks, including:

• monitoring network performance, particularly with regard to:

  • server capacity

  • server load balancing

  • client mount table entries

• adding, modifying and removing imported and exported filesystems as needed using the SCOadmin Filesystem Manager interface.

• troubleshooting mount problems and server connections.

See also:

• ``Configuring the Network File System (NFS)''