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System Administration Guide: Basic Administration

Chapter 18 Managing Services (Overview)

This chapter provides an overview of the Service Management Facility (SMF). In addition, information that is related to run levels is provided.

The following is a list of the information that is in this chapter:

For information on the procedures associated with SMF, see Managing Services (Task Map). For information on the procedures associated with run levels, see Using Run Control Scripts (Task Map).

Introduction to SMF

SMF provides an infrastructure that augments the traditional UNIX start-up scripts, init run levels, and configuration files. SMF provides the following functions:

Dependency statements define the relationships between services. These relationships can be used to provide precise fault containment by restarting only those services that are directly affected by a fault, rather than restarting all of the services. Another advantage of dependency statements is that the statements allow for scalable and reproducible initialization processes. In addition, by defining all of the dependencies, you can take advantage of modern, highly parallel machines, because all independent services can be started in parallel.

SMF defines a set of actions that can be invoked on a service by an administrator. These actions include enable, disable, refresh, restart, and maintain. Each service is managed by a service restarter which carries out the administrative actions. In general, the restarters carry out actions by executing methods for a service. Methods for each service are defined in the service configuration repository. These methods allow the restarter to move the service from one state to another state.

The service configuration repository provides a per-service snapshot at the time that each service is successfully started so that fallback is possible. In addition, the repository provides a consistent and persistent way to enable or disable a service, as well as a consistent view of service state. This capability helps you debug service configuration problems.

Changes in Behavior When Using SMF

Most of the features that are provided by SMF happen behind the scenes, so users are not aware of them. Other features are accessed by new commands. Here is a list of the behavior changes that are most visible.

SMF Concepts

This section presents terms and their definitions within the SMF framework. These terms are used throughout the documentation. To grasp SMF concepts, an understanding of these terms is essential.

SMF Service

The fundamental unit of administration in the SMF framework is the service instance. Each SMF service has the potential to have multiple versions of it configured. As well, multiple instances of the same version can run on a single Oracle Solaris system. An instance is a specific configuration of a service. A web server is a service. A specific web server daemon that is configured to listen on port 80 is an instance. Each instance of the web server service could have different configuration requirements. The service has system-wide configuration requirements, but each instance can override specific requirements, as needed. Multiple instances of a single service are managed as child objects of the service object.

Services are not just the representation for standard long-running system services such as in.dhcpd or nfsd. Services also represent varied system entities that include ISV applications such as Oracle software. In addition, a service can include less traditional entities such as the following:

Generically, a service is an entity that provides a list of capabilities to applications and other services, local and remote. A service is dependent on an implicitly declared list of local services.

A milestone is a special type of service. Milestone services represent high-level attributes of the system. For example, the services which constitute run levels S, 2, and 3 are each represented by milestone services.

Service Identifiers

Each service instance is named with a Fault Management Resource Identifier or FMRI. The FMRI includes the service name and the instance name. For example, the FMRI for the rlogin service is svc:/network/login:rlogin, where network/login identifies the service and rlogin identifies the service instance.

Equivalent formats for an FMRI are as follows:

In addition, some SMF commands can use the following FMRI format: svc:/system/system-log. Some commands infer what instance to use, when there is no ambiguity. See the SMF command man pages, such as svcadm(1M) or svcs(1), for instructions about which FMRI formats are appropriate.

The service names usually include a general functional category. The categories include the following:

Legacy init.d scripts are also represented with FMRIs that start with lrc instead of svc, for example: lrc:/etc/rcS_d/S35cacheos_sh. The legacy services can be monitored using SMF. However, you cannot administer these services.

When booting a system for the first time with SMF, services listed in /etc/inetd.conf are automatically converted into SMF services. The FMRIs for these services are slightly different. The syntax for a converted inetd services is:


network/<service-name>/<protocol>

In addition, the syntax for a converted service that uses the RPC protocol is:


network/rpc-<service-name>/rpc_<protocol>

Where <service-name> is the name defined in /etc/inetd.conf and <protocol> is the protocol for the service. For instance, the FMRI for the rpc.cmsd service is network/rpc-100068_2-5/rpc_udp.

Service States

The svcs command displays the state, start time, and FMRI of service instances. The state of each service is one of the following:

SMF Manifests

An SMF manifest is an XML file that contains a complete set of properties that are associated with a service or a service instance. The files are stored in /var/svc/manifest. Manifests should not be used to modify the properties of a service. The service configuration repository is the authoritative source of configuration information. To incorporate information from the manifest into the repository, you must either run svccfg import or allow the service to import the information during a system boot.

See the service_bundle(4) man page for a complete description of the contents of the SMF manifests. If you need to change the properties of a service, see the svccfg(1M) or inetadm(1M) man pages.

SMF Profiles

An SMF profile is an XML file that lists a set of service instances and whether each should be enabled or disabled. Some profiles which are delivered with the Oracle Solaris release include:

During the first boot after a new installation or an upgrade to the Oracle Solaris OS, some Solaris profiles are automatically applied. To be specific, the /var/svc/profile/generic.xml profile is applied. This file is usually symbolically linked to generic_open.xml or generic_limited_net.xml. Also, if a profile called site.xml is in /var/svc/profile during the first boot or is added between boots, the contents of this profile are applied. By using the site.xml profile, the initial set of enabled services may be customized by the administrator.

For more information about using profiles, see How to Apply an SMF Profile.

Service Configuration Repository

The service configuration repository stores persistent configuration information as well as SMF runtime data for services. The repository is distributed among local memory and local files. SMF is designed so that eventually, service data can be represented in the network directory service. The network directory service is not yet available. The data in the service configuration repository allows for the sharing of configuration information and administrative simplicity across many Solaris instances. The service configuration repository can only be manipulated or queried using SMF interfaces. For more information about manipulating and accessing the repository, see the svccfg(1M) and svcprop(1) man pages. The service configuration repository daemon is covered in the svc.configd(1M) man page. The service configuration library is documented in the libscf(3LIB) man page.

SMF Repository Backups

SMF automatically takes the following backups of the repository:

Four backups of each type are maintained by the system. The system deletes the oldest backup, when necessary. The backups are stored as /etc/svc/repository-type-YYYYMMDD_HHMMSWS, where YYYYMMDD (year, month, day) and HHMMSS (hour, minute, second), are the date and time when the backup was taken. Note that the hour format is based on a 24–hour clock.

You can restore the repository from these backups, if an error occurs. To do so, use the /lib/svc/bin/restore_repository command. For more information, see How to Repair a Corrupt Repository.

SMF Snapshots

The data in the service configuration repository includes snapshots, as well as a configuration that can be edited. Data about each service instance is stored in the snapshots. The standard snapshots are as follows:

The SMF service always executes with the running snapshot. This snapshot is automatically created if it does not exist.

The svcadm refresh command, sometimes followed by the svcadm restart command, makes a snapshot active. The svccfg command is used to view or revert to instance configurations in a previous snapshot. See How to Revert to Another SMF Snapshot for more information.

SMF Administrative and Programming Interfaces

This section introduces the interfaces that are available when you use SMF.

SMF Command-Line Administrative Utilities

SMF provides a set of command-line utilities that interact with SMF and accomplish standard administrative tasks. The following utilities can be used to administer SMF.

Table 18–1 Service Management Facility Utilities

Command Name 

Function 

inetadm

Provides the ability to observe or configure services controlled by inetd

svcadm

Provides the ability to perform common service management tasks, such as enabling, disabling, or restarting service instances

svccfg

Provides the ability to display and manipulate the contents of the service configuration repository

svcprop

Retrieves property values from the service configuration repository with a output format appropriate for use in shell scripts

svcs

Gives detailed views of the service state of all service instances in the service configuration repository

Service Management Configuration Library Interfaces

SMF provides a set of programming interfaces that are used to interact with the service configuration repository through the svc.configd daemon. This daemon is the arbiter of all requests to the local repository datastores. A set of fundamental interfaces is defined as the lowest level of interaction possible with services in the service configuration repository. The interfaces provide access to all service configuration repository features such as transactions and snapshots.

Many developers only need a set of common tasks to interact with SMF. These tasks are implemented as convenience functions on top of the fundamental services to ease the implementation burden.

SMF Components

SMF includes a master restarter daemon and delegated restarters.

SMF Master Restarter Daemon

The svc.startd daemon is the master process starter and restarter for the Solaris OS. The daemon is responsible for managing service dependencies for the entire system. The daemon takes on the previous responsibility that init held of starting the appropriate /etc/rc*.d scripts at the appropriate run levels. First, svc.startd retrieves the information in the service configuration repository. Next, the daemon starts services when their dependencies are met. The daemon is also responsible for restarting services that have failed and for shutting down services whose dependencies are no longer satisfied. The daemon keeps track of service state through an operating system view of availability through events such as process death.

SMF Delegated Restarters

Some services have a set of common behaviors on startup. To provide commonality among these services, a delegated restarter might take responsibility for these services. In addition, a delegated restarter can be used to provide more complex or application-specific restarting behavior. The delegated restarter can support a different set of methods, but exports the same service states as the master restarter. The restarter's name is stored with the service. A current example of a delegated restarter is inetd, which can start Internet services on demand, rather than having the services always running.

SMF and Booting

SMF provides new methods for booting a system. For instance:

SMF Compatibility

While many standard Solaris services are now managed by SMF, the scripts placed in /etc/rc*.d continue to be executed on run-level transitions. Most of the /etc/rc*.d scripts that were included in previous Solaris releases have been removed as part of SMF. The ability to continue to run the remaining scripts allows for third-party applications to be added without having to convert the services to use SMF.

In addition, /etc/inittab and /etc/inetd.conf must be available for packages to amend with postinstall scripts. These are called legacy-run services. The inetconv command is run to add these legacy-run services to the service configuration repository. The status of these services can be viewed, but no other changes are supported through SMF. Applications that use this feature will not benefit from the precise fault containment provided by SMF.

Applications converted to utilize SMF should no longer make modifications to the /etc/inittab and /etc/inetd.conf files. The converted applications will not use the /etc/rc*.d scripts. Also, the new version of inetd does not look for entries in /etc/inetd.conf.

Run Levels

A system's run level (also known as an init state) defines what services and resources are available to users. A system can be in only one run level at a time.

The Solaris OS has eight run levels, which are described in the following table. The default run level is specified in the /etc/inittab file as run level 3.

Table 18–2 Solaris Run Levels

Run Level 

Init State 

Type 

Purpose 

0 

Power-down state 

Power-down 

To shut down the operating system so that it is safe to turn off power to the system.

s or S

Single-user state

Single-user 

To run as a single user with some file systems mounted and accessible.  

1 

Administrative state 

Single-user 

To access all available file systems. User logins are disabled.

2 

Multiuser state 

Multiuser 

For normal operations. Multiple users can access the system and all file system. All daemons are running except for the NFS server daemons.

3 

Multiuser level with NFS resources shared

Multiuser 

For normal operations with NFS resources shared. This is the default run level for the Solaris OS.

4 

Alternative multiuser state 

 

Not configured by default, but available for customer use. 

5 

Power-down state 

Power-down 

To shut down the operating system so that it is safe to turn off power to the system. If possible, automatically turns off power on systems that support this feature. 

6 

Reboot state 

Reboot 

To shut down the system to run level 0, and then reboot to multiuser level with NFS resources shared (or whatever level is the default in the inittab file).

In addition, the svcadm command can be used to change the run level of a system, by selecting a milestone at which to run. The following table shows which run level corresponds to each milestone.

Table 18–3 Solaris Run Levels and SMF Milestones

Run Level 

SMF Milestone FMRI 

S 

milestone/single-user:default

2 

milestone/multi-user:default

3 

milestone/multi-user-server:default

When to Use Run Levels or Milestones

Under most circumstances, using the init command with a run level to change the system state is sufficient. Using milestones to change system state can be confusing and can lead to unexpected behavior. In addition, the init command allows for the system to be shutdown, so init is the best command for changing system state.

However, booting a system using the none milestone, can be very useful when debugging startup problems. There is no equivalent run level to the none milestone. See How to Boot Without Starting Any Services for specific instructions.

Determining a System's Run Level

Display run level information by using the who -r command.


$ who -r

Use the who -r command to determine a system's current run level for any level.

Example 18–1 Determining a System's Run Level

This example displays information about a system's current run level and previous run levels.


$ who -r
 .    run-level 3  Dec 13 10:10  3  0 S
$

Output of who -r command

Description 

run-level 3

Identifies the current run level 

Dec 13 10:10

Identifies the date of last run level change 

3

Also identifies the current run level 

0

Identifies the number of times the system has been at this run level since the last reboot 

S

Identifies the previous run level 

/etc/inittab File

When you boot the system or change run levels with the init or shutdown command, the init daemon starts processes by reading information from the /etc/inittab file. This file defines these important items for the init process:

Each entry in the /etc/inittab file has the following fields:

id:rstate:action:process

The following table describes the fields in an inittab entry.

Table 18–4 Fields Descriptions for the inittab File

Field 

Description 

id

Is a unique identifier for the entry. 

rstate

Lists the run levels to which this entry applies. 

action

Identifies how the process that is specified in the process field is to be run. Possible values include: sysinit, boot, bootwait, wait, and respawn.

For a description of the other action keywords, see inittab(4).

process

Defines the command or script to execute. 

Example 18–2 Default inittab File

The following example shows a default inittab file that is installed with the Solaris release. A description for each line of output in this example follows.


ap::sysinit:/sbin/autopush -f /etc/iu.ap  (1)
sp::sysinit:/sbin/soconfig -f /etc/sock2path             (2)
smf::sysinit:/lib/svc/bin/svc.startd    >/dev/msglog 2<>/dev/msglog      (3)
p3:s1234:powerfail:/usr/sbin/shutdown -y -i5 -g0 >/dev/msglog 2<>/dev/...(4)

  1. Initializes STREAMS modules

  2. Configures socket transport providers

  3. Initializes the master restarter for SMF

  4. Describes a power fail shutdown

What Happens When the System Is Brought to Run Level 3

  1. The init process is started and reads the /etc/default/init file to set any environment variables. By default, only the TIMEZONE variable is set.

    2. Then, init reads the inittab file and does the following:

    1. Executes any process entries that have sysinit in the action field so that any special initializations can take place before users login.

    2. Passes the startup activities to svc.startd.

    For a detailed description of how the init process uses the inittab file, see init(1M).