HP-UX System Administrator's Guide: Overview HP-UX 11i v3 (B3921-90011, September 2010)

1. First, notify everyone who is likely to be affected by the shutdown, giving them a chance to
complete work in progress, and if necessary unmount file systems that were NFS-mounted
from your system.
2. Then, shutdown any programs you might be running that would not be safely shutdown
by one of the system’s kill scripts (“Startup and Kill Scripts (Run Level Transitions)”).
3. Finally, use the shutdown command to shut down the system. The shutdown command:
a. allows you to notify the users of the system of the shutdown in progress if you have
not previously done so, or to remind those users that the shutdown is imminent.
b. transitions backward through the run levels (executing the kill links in the directories
/sbin/rc[0-4].d)
c. and finally calls reboot to perform a sync operation that insures memory structures
are written to disk before memory is overwritten by the subsequent boot.
For details on the HP-UX shut down process, see HP-UX System Administrator’s Guide: Routine
Management Tasks.
Abnormal Shutdowns (System Crashes)
When your system crashes, it is important to know why so that you can take actions to prevent
it from happening again. Sometimes, it is easy to determine why: for example, if somebody trips
over the cable connecting your computer to the disk containing your root file system
(disconnecting the disk).
At other times, the cause of the crash might not be so obvious. In extreme cases, you might want
or need to analyze a snapshot of the computer’s memory at the time of the crash, or have HP do
it for you, in order to determine the cause of the crash.
Overview of the Dump / Save Cycle
When the system crashes, in order to preserve the evidence of what caused the crash, HP-UX
tries to save the image of physical memory, or certain portions of it, to predefined locations called
dump devices. When the system is subsequently rebooted, a special utility copies the memory
image from the dump devices to the HP-UX file system area.
Figure 3-8 The Crash Dump Sequence
Normal Operation
✘
System Crash!
System Reboot
Resume
Normal Operation
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Crash-time
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Dump Devices
HP-UX
File System Disks
When the memory image is in the HP-UX file system, you can analyze it with a debugger or save
it to removable media for shipment to someone else for analysis.
There are multiple ways that dump devices can be configured:
78 Major Components of HP-UX