SUNW.gds(5) (Sun Cluster 3.1 Reference Manual)

Sun Cluster 3.1 Reference Manual

SUNW.gds(5)

NAME | DESCRIPTION | EXAMPLES | ATTRIBUTES | SEE ALSO

NAME

SUNW.gds– The Generic Data Service (GDS) is a resource type for making simple network-aware applications highly available or scalable.

DESCRIPTION

GDS is a mechanism for making simple network-aware applications highly available or scalable by plugging then into the Sun Cluster resource Group Management (RGM) framework.

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

Standard Properties

Network_resources_used

Category: Optional
Default: Null
Tunable: At creation

If this property is omitted, the application is assumed to listen on all addresses. This property need not be specified unless the application binds to one or more specific addresses. See r_properties(5) for details.

Before creating the GDS resource, a LogicalHostname or SharedAddress resource must already have been configured in the same resource group as the GDS resource. See Sun Cluster 3.0 Data Services Installation and Configuration Guide for information on how to configure a LogicalHostname or SharedAddress resource.

Port_list

Category: Required
Default: No Default
Tunable: At creation

List of port numbers that the application listens on. See r_properties(5) for details.

Extension Properties

Start_command

Category: Required
Default: No Default
Tunable: At creation
Type: String

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

Stop_command

Category: Optional
Default: Null
Tunable: At creation
Type: String

This optional parameter specifies the stop command for the application. It must be a complete command line that can be passed directly to a shell to stop the application. If this property is omitted, the Generic Data Service stops the application using signals.

Probe_command

Category: Optional
Default: Null
Tunable: At creation
Type: String

The probe command periodically checks the health of the application. It 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 OK.

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, can be an integer between 0 (for success) and 100 (for complete failure). The probe status can also be a special value of 201 which results in immediate failover of the application unless Failover_enables is set to False. The probe status is used within the GDS probing algorithm to make the decision of restarting the application locally, as opposed to failing the application over to another node. 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, it disconnects immediately. If both connect and disconnect succeed, the application is deemed to be running healthily.

Probe_timeout

Category: Optional
Default: 30
Tunable: Any time
Type: Integer

This property specifies the timeout value in seconds for the probe command.

Child_mon_level

Category: Optional
Default: -1
Tunable: At creation
Type: Integer

This property provides control over which processes get monitored through PMF. It denotes the level up to which the forked children processes are monitored. This is similar to the -C argument to the pmfadm command. Omitting this property, or setting it to the default value of -1, has the same effect as omitting the -C option on the pmfadm command; that is, all children (and their descendents) will be monitored. See the pmfadm(1M) man page for more details.

Failover_enabled

Category: Optional
Default: true
Tunable: When disabled
Type: Boolean

This property allows the failover of the resource. If the property is set to false, failover of the resource is disabled. This can be used to prevent the application resource from initiating a failover of the resource group.

Stop_signal

Category: Optional
Default: 15
Tunable: When disabled
Type: Integer

This property specifies the signal used to stop the application. The values of this property are the same as those defined in signal(3head).

EXAMPLES

The following sequence of commands illustrates how to make a given application, named app, highly available using the GDS. The SunPlex Agent Builder (scdsbuilder(1HA)) GUI tool can be used to create driving scripts that contain these commands.

Basic Example

# Register the SUNW.gds resource type 
scrgadm -a -t SUNW.gds

# Create a resource group for the application
scrgadm -a -g rg1

# Create the LogicalHostname resource 
# for the logical hostname 'hhead'
scrgadm -a -L -g rg1 -l hhead

# Create the application resource
scrgadm -a -t SUNW.gds -g rg1 -j app-rs \  
        -x Start_command="/usr/local/app/bin/start" \  
        -y Port_list="1234/tcp" 

# Manage the resource group, enable all the resources, and bring 
# them online
scswitch -Z -g rg1

# At this point, the application will be up and running in a highly 
# available fashion being monitored by the simple probe provided by 
# GDS. The status of the application can now be checked using the 
# following command:
scstat -g rg1

Complex Example

# Register the SUNW.gds resource type 
scrgadm -a -t SUNW.gds

# Create a resource group for the application
scrgadm -a -g rg1

# Create the LogicalHostname resource
# for the logical hostname 'hhead'
scrgadm -a -L -g rg1 -l hhead

# Create the application resource
scrgadm -a -t SUNW.gds -g rg1 -j app-rs  \  
        -x Start_command="/usr/local/app/bin/start" \  
        -x Stop_command="/usr/local/app/bin/stop"   \ 
        -x Probe_command="/usr/local/app/bin/probe" \  
        -x stop_signal=9 -x failover_enabled=false  \ 
        -y Start_timeout=120 -y Stop_timeout=180    \ 
        -y Port_list="1234/tcp" \  
        -x Probe_timeout=60

# Manage the resource group, enable all the resources, and bring 
# them online
scswitch -Z -g rg1

# At this point, the application will be up and running in a highly 
# available fashion being monitored by the fault monitor specified 
# on the Probe_command. The status of the application can now be 
# checked using the following command:
scstat -g rg1

ATTRIBUTES

See attributes(5) for a description of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Availability	SUNWscgds