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

For a more detailed discussion of using fsck to repair file systems, refer to the following
manpages:
• fsck(1M)
• fsck_cachefs(1M)
• fsck_hfs(1M)
• fsck_vxfs(1M)
System Crashes / HP-UX Panics
Although rare, sometimes systems can shut themselves down unexpectedly in an event
known as a system crash or system panic. For a detailed description of what to do if
this happens, and an explanation of what takes place following a system crash, see
“Configuring Dump Devices” (page 92).
Single-User Mode
A special operating mode, called single-user mode, is available on HP-UX systems.
While your system is in single-user mode only the console is active, and a lot of the
subsystems for HP-UX are not running. This mode is usually used for system
maintenance. There are two ways to put your system into single-user mode:
1. Boot the system into single-user mode (for information on booting Itanium Server
systems into single-user mode see “Booting into Single-User Mode” (page 54), or
for information about booting PA-RISC servers into single-user mode see“Booting
into Single-User Mode” (page 68)).
2. Shut the system down into single-user mode from a higher running mode (see
“Normal (Planned) Shutdown” (page 85)).
Special Considerations for Shutting Down Certain Systems
In today’s world of networked computers, people who are not direct users of your
system can still be affected by its absence from the network (when it has been shut
down). If your system is serving one or more of the following functions, you need to
at least consider the impact to users of other systems when you plan to take your system
down; and, if possible, you should try to let them know in advance that they will be
affected, so that they can prepare for the event.
Mail Server
If your system is a mail server, it receives e-mail on behalf of its users, and is often the
computer handling the outgoing e-mail for them too. When your system is down,
incoming mail is usually held by other computers in the network for delivery when
your system is back on line. If your computer will be down for an extended period of
time, it is possible that others sending e-mail to your computer’s users will have their
e-mail returned as being undeliverable.
90 Booting and Shutdown