HP-UX System Administrator's Guide: Routine Management Tasks HP-UX 11i v3 (B3921-90023, September 2010)

For a more detailed discussion of using fsck to repair file systems, see 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 90).
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 53), or
for information about booting PA-RISC servers into single-user mode see“Booting
into Single-User Mode” (page 67)).
2. Shut the system down into single-user mode from a higher running mode (see
“Normal (Planned) Shutdown” (page 83)).
Special Considerations for Shutting Down Certain Systems
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.
88 Booting and Shutdown