System Administration Guide, Volume 1

Chapter 7 Shutting Down and Booting a System (Overview)

This chapter provides guidelines for shutting down and booting a system. The Solaris software environment is designed to run continuously so that electronic mail and network resources are available to users. Occasionally, it is necessary to shut down or reboot a system because of a system configuration change, a scheduled maintenance event, or a power outage.

This is a list of overview information in this chapter.

What's New in Shutting Down and Booting a System?

This section describes new features related to shutting down and booting a system in this Solaris release.

Booting a System Over the Network With DHCP

Dynamic Host Configuration Protocol (DHCP) functionality has been added to boot a system over the network in this Solaris release. The previous network boot technology based on RARP/bootparams is still available.

A DHCP server must have been installed and configured in your network before you can use DHCP booting. For information on setting up a DHCP server, see "Configuring DHCP Service" in System Administration Guide, Volume 3.

For information on booting a SPARC based system over the network, see "SPARC: How to Boot a System Over the Network". For information on booting an IA based system over the network, see "IA: How to Boot a System Over the Network".

IA: Booting From CD-ROM Without the Solaris Boot Diskette

You can boot the Solaris 8 (Intel Platform Edition) directly from the locally attached CD-ROM without the Solaris boot diskette on IA based systems that support this feature.

The Solaris boot diskette is still available for the systems that do not support this feature.

See Solaris 8 (Intel Platform Edition) Installation Guide for information on booting IA based systems with or without the boot diskette.

Where to Find Shutting Down and Booting Tasks

Use these references to find step-by-step instructions for shutting down and booting a system.

For Information On ...	See ...
Shutting down a SPARC based or IA based system	Chapter 9, Shutting Down a System (Tasks)
Booting a SPARC based system	Chapter 10, SPARC: Booting a System (Tasks)
Booting an IA based system	Chapter 11, IA: Booting a System (Tasks)
Managing a SPARC based system with the power management software	Using Power Management

Shutting Down and Booting Terminology

This section describes the terminology used in shutting down and booting a system.

Run levels and init states - A run level is a letter or digit representing a system state in which a particular set of system services are available. The system is always running in one of a set of well-defined run levels. Run levels are also referred to as init states because the init process is used to perform transitions between run levels. System administrators use the init(1M) command to initiate a run-level transition. This book refers to init states as run levels.
Boot types - A boot type describes how a system is booted. Different boot types include:
- Interactive boot - You are prompted to provide information about how the system is booted, such as the kernel and device path name.
- Reconfiguration boot - The system is reconfigured to support newly added hardware or new pseudo devices.
- Recovery boot - The system is hung or an invalid entry is prohibiting the system from booting successfully or from allowing users to log in.

Guidelines for Shutting Down a System

Keep the following in mind when shutting down a system:

Use the init and shutdown commands to shut down a system. Both commands perform a clean system shutdown, which means all system processes and services are terminated normally.
Use the shutdown command to shut down a server, because logged-in users and systems mounting resources from the server are notified before the server is shut down. Additional notification of system shutdowns via electronic mail is also recommended so that users can be prepared for system downtime.
You need superuser privileges to use the shutdown or init command to shut down a system.
Both shutdown and init commands take a run level as an argument. The three most common run levels are:
- Run level 3 - Means that all system resources are available and users can log in. By default, booting a system brings it to run level 3, which is used for normal day-to-day operations. Also known as multiuser level with NFS resources shared.
- Run level 6 - Stops the operating system and reboots to the state defined by the initdefault entry in the /etc/inittab file.
- Run level 0 - Means the operating system is shut down and it is safe to turn off power. Bringing a system to run level 0 is needed whenever the system is moved or hardware is added or removed.
- Run levels are fully described in Chapter 8, Run Levels and Boot Files (Tasks).

Guidelines for Booting a System

Keep the following in mind when booting a system:

After a system is shut down, it is booted by using the boot command at the PROM level on a SPARC based system or by using the boot command at the Primary Boot Subsystem Menu on an Intel system.
A system can be rebooted by turning the power off and then back on. This is not a clean shutdown because system services and processes are terminated abruptly. However, turning a system's power off and back is an alternative for emergency situations.
SPARC based and IA based systems use different hardware components for booting. These differences are described in Chapter 12, The Boot Process (Reference).

Performing a Reconfiguration Boot

Perform a reconfiguration boot when adding new hardware to the system. See the table below to determine which reconfiguration procedure to use.

Table 7-1 Reconfiguration Procedures


If You Are Reconfiguring The System To ...	See ...
Add a secondary disk	Chapter 30, SPARC: Adding a Disk (Tasks) or Chapter 31, IA: Adding a Disk (Tasks)
Add some other peripheral device	"How to Add a Peripheral Device"

When to Shut Down a System

The following table provides a list of system administration tasks and the type of shut down needed to initiate the task.

Table 7-2 Shutting Down a System


If You Are ...	Change To This Run Level ...	See ...
Turning off system power due to anticipated power outage	Run level 0, where it is safe to turn off power	Chapter 9, Shutting Down a System (Tasks)
Changing kernel parameters in the `/etc/system` file	Run level 6 (reboot the system)	Chapter 9, Shutting Down a System (Tasks)
Performing file system maintenance, such as backing up or restoring system data	Run level S (single-user mode)	Chapter 9, Shutting Down a System (Tasks)
Repairing a system configuration file such as `/etc/system`	See "When to Boot a System"	N/A
Adding or removing hardware from the system	Reconfiguration boot (plus turning off power when adding or removing hardware)	Chapter 24, Device Management (Overview)
Repairing an important system file which is causing system boot failure	See "When to Boot a System"	N/A
Booting the kernel debugger (`kadb`) to track down a system problem	Run level 0, if possible	Chapter 9, Shutting Down a System (Tasks)
Recovering from a hung system and you want to force a crash dump	See "When to Boot a System"	N/A

See Chapter 9, Shutting Down a System (Tasks) for examples of shutting down a server or standalone system.

When to Boot a System

The table below provides a list of system administration tasks and the corresponding boot type used to complete the task.

Table 7-3 Booting a System


If You Are Rebooting the System After ...	Use This Boot Type ...	See SPARC Procedure ...	See IA Procedure ...
Turning off system power due to anticipated power outage	Turn system power back on	Chapter 9, Shutting Down a System (Tasks)	Chapter 9, Shutting Down a System (Tasks)
Changing kernel parameters in the `/etc/system` file	Reboot the system to run level 3 (multiuser mode with NFS resources shared)	"SPARC: How to Boot a System to Run Level 3 (Multiuser State)"	"IA: How to Boot a System to Run Level 3 (Multiuser State)"
Performing file system maintenance, such as performing a backup or restoring system data	Use Control-d from run level S to bring the system back to run level 3	"SPARC: How to Boot a System to Run Level S (Single-User State)"	"IA: How to Boot a System to Run Level S (Single-User State)"
Repairing a system configuration file such as `/etc/system`	Interactive boot	"SPARC: How to Boot a System Interactively"	"IA: How to Boot a System Interactively"
Adding or removing hardware from the system	Reconfiguration boot (plus turning on system power after adding or removing hardware)	"SPARC: How to Connect a Secondary Disk and Boot"	Chapter 31, IA: Adding a Disk (Tasks)
Booting the kernel debugger (`kadb`) to track down a system problem	Booting `kabd`	"SPARC: How to Boot the System With the Kernel Debugger (`kadb`)"	"IA: How to Boot a System with the Kernel Debugger (`kadb`)"
Repairing an important system file which is causing system boot failure	Recovery boot	"IA: How to Boot a System for Recovery Purposes"	"IA: How to Boot a System for Recovery Purposes"
Recovering from a hung system and you want to force a crash dump	Recovery boot	See example on "IA: How to Force a Crash Dump and Reboot the System"	See example on "IA: How to Force a Crash Dump and Reboot the System"

See Chapter 10, SPARC: Booting a System (Tasks) or Chapter 11, IA: Booting a System (Tasks) for examples of booting a system.