SUNW.gds(5) (Sun Cluster Reference Manual for Solaris OS)

Sun Cluster Reference Manual for Solaris OS

SUNW.gds(5)

NAME | DESCRIPTION | EXAMPLES | ATTRIBUTES | SEE ALSO

NAME

SUNW.gds– resource type for making simple network-aware and nonnetwork-aware applications highly available or scalable

DESCRIPTION

The Generic Data Service (GDS) is a mechanism that enables you to make simple network-aware and nonnetwork-aware applications highly available or scalable by plugging them into the Sun Cluster Resource Group Manager (RGM) framework.

The GDS contains a fully functional Sun Cluster resource type, complete with callback methods (rt_callbacks(1HA)) and a Resource Type Registration (RTR) file (rt_reg(4)).

Standard Properties

Network_resources_used (string array)

A list of logical-hostname or shared-address network resources upon which this resource has a dependency. This list contains all network-address resources that appear in the properties Resource_dependencies, Resource_dependencies_weak, Resource_dependencies_restart, or Resource_dependencies_offline_restart.

This property is updated automatically by the RGM, based on the setting of the resource-dependencies properties. You do not set this property directly. Instead, use the Resource_dependencies property.

Category: Conditional/Optional
Default: The empty list
Tunable: Any time

Port_list (string array)

Specifies a comma-separated list of port numbers on which the application listens. See the r_properties(5) man page.

The Port_list property must be specified in the start script that Agent Builder creates or with the clresource command if you are using Sun Cluster administration commands.

Category: Conditional/Required
Default: No default
Tunable: Any time

Resource_dependencies (string array)

Specifies a list of resources upon which a resource depends. This list includes any logical-hostname or shared-address network resources that are used by a resource. The default value for this property is null. You must specify this property if the application needs to bind to one or more specific addresses. If no network resource dependencies are specified, the application listens on all addresses.

Before you create the GDS resource, a LogicalHostname or SharedAddress resource must already be configured.

You can specify one or more resource names. Each network resource can contain one or more logical hostnames. See the clreslogicalhostname(1CL) and clressharedaddress(1CL) man pages for more information.

You can specify an alternate kind of dependency by using the Resource_dependencies_weak, Resource_dependencies_restart, or Resource_dependencies_offline_restart property instead of the Resource_dependencies property. For more information, see the r_properties(5) man page.

Category: Optional
Default: The empty list
Tunable: Any time

Start_timeout (integer)

Specifies the timeout value, in seconds, for the start command.

Category: Optional
Default: 300 seconds
Tunable: Any time

Stop_timeout (integer)

Specifies the timeout value, in seconds, for the stop command.

Category: Optional
Default: 300 seconds
Tunable: Any time

Validate_timeout (integer)

Specifies the timeout value, in seconds, for the validate command.

Category: Optional
Default: 300 seconds
Tunable: Any time

Extension Properties

Child_mon_level (integer)

Provides control over the processes that are monitored through the Process Monitor Facility (PMF). This property denotes the level to which the forked children processes are monitored. Omitting this property or setting this property to the default value is the same as omitting the -C option for pmfadm(1M): all children (and their descendents) are monitored.

Category: Optional
Default: -1
Tunable: At creation

Failover_enabled (boolean)

Allows the resource to fail over. If this property is set to False, failover of the resource is disabled. You can use this property to prevent the application resource from initiating a failover of the resource group.

Note –

Use the Failover_mode property instead of the Failover_enabled extension property because Failover_mode better controls failover behavior. For more information, see the descriptions of the LOG_ONLY and RESTART_ONLY values for Failover_mode in r_properties(5).

Category: Optional
Default: True
Tunable: When disabled

Log_level (enum)

Specifies the level, or type, of diagnostic messages that are logged by GDS. You can specify None, Info, or Err for this property. When you specify None, diagnostic messages are not logged by GDS. When you specify Info, both information and error messages are logged. When you specify Err, only error messages are logged.

Category: Optional
Default: Info
Tunable: Any time

Probe_command (string)

Specifies the command that periodically checks the health of a network-aware or nonnetwork-aware application. This command must be a complete command line that can be passed directly to a shell to probe the application. The probe command returns with an exit status of 0 if the application is running correctly.

The exit status of the probe command is used to determine the severity of the failure of the application. This exit status, called probe status, is an integer between 0 (for success) and 100 (for complete failure). The probe status can also be 201, which causes the application to fail over unless Failover_enabled is set to False.

The probe status is used within the GDS probing algorithm to determine whether to restart the application locally or to fail over the application to another node or zone. If the probe command is omitted, the GDS provides its own simple probe that connects to the application on the network resource. If the connect succeeds, the GDS disconnects immediately. If both connect and disconnect succeed, the application is deemed to be running correctly.

The GDS does not provide “default” probing behavior for nonnetwork-aware applications. However, a nonnetwork-aware application is started under the PMF, which monitors the application and restarts the application if it fails. The pmfadm(1M) man page contains more information.

Category: Optional
Default: Null
Tunable: When disabled

Probe_timeout (integer)

Specifies the timeout value, in seconds, for the probe command.

Category: Optional
Default: 30 seconds
Tunable: Any time

Start_command (string)

Specifies the command that starts the application. This command must be a complete command line that can be passed directly to a shell to start the application.

The start command, or one of its forked children, is expected to be a long-running program or daemon which actually provides the service to clients. The start command process tree is monitored by the Process Monitor Facility (PMF) as described under the Child_mon_level extension property. If the monitored processes exit, they are restarted according to the settings of the Retry_count and Retry_interval resource properties. If the retry count is exceeded, an attempt is made to relocate the resource group to a different node or zone.

The exit status that is returned by the start command or its children is ignored.

Category: Required
Default: No default
Tunable: When disabled

Stop_command (string)

Specifies the command that stops the application. This command must be a complete command line that can be passed directly to a shell to stop the application. If this property is omitted, or if the stop command exits nonzero, the GDS stops the application by using signals.

Category: Optional
Default: Null
Tunable: When disabled

Stop_signal (integer)

Specifies the signal that stops the application. The values of this property are the same as those defined in signal(3HEAD).

Category: Optional
Default: 15
Tunable: When disabled

Validate_command (string)

Specifies the absolute path to the command that validates the application. If you do not provide an absolute path, the application is not validated.

The exit status of the validate command is used to determine whether the creation or update of the GDS resource should be permitted. Before creating or updating the resource, the specified validate command is executed on each node of the node list of the resource group that contains the resource. If the validate command exits nonzero, the requested resource creation or update is not permitted. Any output that is written to stdout or stderr by the validate command will be passed back to the user who issued the administrative command to create or update the resource. Such output can be used to explain why the resource validation failed.

The validate command is also executed when bringing the gds resource online, before executing the Start_command extension property. If the validate command exits nonzero, it is treated as a start failure.

The validate command is also executed before performing the GIVEOVER option of the scha_control command to relocate the resource group to a new node or zone. If the command exits nonzero, the giveover is blocked and the resource group remains mastered on its current node or zone.

Category: Optional
Default: Null
Tunable: When disabled

EXAMPLES

The following examples show how to use GDS to make an application named app highly available. You can also use Sun Cluster Agent Builder (scdsbuilder(1HA)) to create scripts that contain these commands.

Basic Example

This example shows how to register the SUNW.gds resource type, create a resource group for the application, create the LogicalHostname resource for the logical host name hhead, create the application resource, and then manage the resource group, enable all its resources, and bring its resources online.

At this point, the application is running, highly available, and monitored by the simple probe that is provided by GDS. You can now check the status of the application.

# clresourcetype register SUNW.gds
# clresourcegroup create rg1
# clreslogicalhostname create -g rg1 -h hhead
# clresource create -g rg1 -t SUNW.gds \
-p Start_command="/usr/local/app/bin/start" \
-p Port_list="1234/tcp" app-rs
# clresourcegroup online -M rg1
# clresourcegroup status +

Complex Example

This example shows how to register the SUNW.gds resource type, create a resource group for the application, create the LogicalHostname resource for the logical host name hhead, create the application resource, log error messages only, and then manage the resource group, enable all the resources, and bring the resources online.

At this point, the application is running, highly available, and monitored by the fault monitor that is specified by Probe_command. You can now check the status of the application.

# clresourcetype register SUNW.gds
# clresourcegroup create rg1
# clreslogicalhostname create -g rg1 -h hhead
# clresource create -g rg1 -t SUNW.gds \
-p Start_command="/usr/local/app/bin/start" \
-p Stop_command="/usr/local/app/bin/stop" \
-p Validate_command="/usr/local/app/bin/config" \
-p Probe_command="/usr/local/app/bin/probe" \
-p stop_signal=9 -p failover_enabled=FALSE \
-p Start_timeout=120 -p Stop_timeout=180 \
-p Port_list="1234/tcp" -p Probe_timeout=60 \
-p Validate_timeout=120 -p Log_level=Err app-rs
# clresourcegroup online -M rg1
# clresourcegroup status +

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	`SUNWscgds`