Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Booting and Shutdown
Shutting Down Systems
Chapter 5 529
Network Gateway
If your computer is serving as a network gateway computer: that is, it
has several network interface cards in it, and is a member of multiple
networks (subnets), your computer’s absence on the network can have a
huge impact on network operations. An example of this is the computer
called flserver in the MSW Sample Network (see “The MSW Network
(Overview)” on page 67). While such a computer is down, computers on
one of the subnets are unable to communicate with computers on other
subnets, unless other gateway computers exist that can handle the
traffic.
Plan very carefully for such shutdowns and make sure users of the
network are notified as far in advance as possible that they will be
unable to communicate with computers on the other subnets.
TIP If you have multiple subnets in your network, try whenever possible to
build redundancy into the network so that you can freely take a
computer off line without prohibiting network traffic flow.
NFS File Server
If your computer is an NFS file server, other computers in the network
have mounted one or more of your computer’s file systems to be a part of
their own directory trees. When your system goes down, attempts to
access the files or directories of your system by users on the other
systems will result in those accesses hanging indefinitely. A reboot of the
other systems will likely be required once your system is back on line
before those systems will again be able to access your computer’s file
systems.
The best course of action is to alert the administrators of systems who
have NFS-mounted file systems from your computer to unmount the
NFS-mounted file systems before you shut down your system! By doing
this, they will simply need to re-mount the NFS file systems from your
computer when your computer is back on line. No reboot of the other
systems will be required.
NOTE This can have a cascading effect. For example, if computer A has
NFS-mounted a file system from computer B, and computer B needs to
be rebooted because it had NFS-mounted a different file system from