HP-UX System Administrator's Guide: Routine Management Tasks

— “Network Gateway” (page 91)
— “NFS File Server” (page 91)
— “NFS Client” (page 92)
• “Avoiding a Shutdown When Possible” (page 92)
For additional information on shutting down systems, see HP-UX System Administrator’s
Guide: Overview.
Types of Shutdown
There are various types of shutdown, both planned, and unplanned. This section covers
several common situations:
• A “Normal (Planned) Shutdown” (page 85)
• “Power Failure” (page 88)
• “System Crashes / HP-UX Panics” (page 90)
• “Unclean Shutdowns” (page 89)
Normal (Planned) Shutdown
Hopefully, most of your system shutdowns will be of this type. With a normal
shutdown, you have time to prepare the system and its users so that the system can be
restarted and work can continue with no loss of data, and as little disruption as possible.
As mentioned in the overview to this section, it is important not to simply turn off your
computer (as you might be able to do with a personal computer).
In order to maximize system performance, recently used data from disk files is kept
and updated in memory. Periodically (by default, every 30 seconds), a program called
sync is run to make sure the file systems on disk are kept up to date in the event of an
unplanned shutdown (the on-disk file systems are synchronized with the memory-based
changes). But, if it’s been 29 seconds since the last run of sync, there are probably
memory based changes that are not yet reflected on disk. If the system crashes now,
this can cause inconsistencies in file system structures on disk (which, although not
usually the case, can cause corrupt files or loss of data).
Also, users of both your system and other systems in the network that depend on your
system for some resource will be affected. It is always best to notify them in advance
of any planned shutdown so that they can plan for the shutdown and minimize the
impact to their work.
The basic procedure for a planned shutdown of your system is:
Shutting Down Systems 85