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NAME
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(GDS) is a resource type for making simple network-aware applications highly
available or scalable. |
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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
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Network_resources_used
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Category: Optional
Default: Null
Tunable: At creation
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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.
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Port_list
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Category: Required
Default: No Default
Tunable: At creation
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List of port numbers that the application listens on. See r_properties(5) for details.
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Extension Properties
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Start_command
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Category: Required
Default: No Default
Tunable: At creation
Type: String
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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.
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Stop_command
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Category: Optional
Default: Null
Tunable: At creation
Type: String
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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.
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Probe_command
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Category: Optional
Default: Null
Tunable: At creation
Type: String
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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.
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Probe_timeout
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Category: Optional
Default: 30
Tunable: Any time
Type: Integer
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This property specifies the timeout value in seconds for the probe command.
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Child_mon_level
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Category: Optional
Default: -1
Tunable: At creation
Type: Integer
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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.
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Failover_enabled
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Category: Optional
Default: true
Tunable: When disabled
Type: Boolean
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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.
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Stop_signal
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Category: Optional
Default: 15
Tunable: When disabled
Type: Integer
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This property specifies the signal used to stop the application. The
values of this property are the same as those defined in signal(3head).
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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
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# 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
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Complex Example
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# 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
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See attributes(5) for a description of the following
attributes:
| ATTRIBUTE
TYPE | ATTRIBUTE VALUE |
| Availability | SUNWscgds |
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rt_callbacks(1HA), scdsbuilder(1HA), scha_resource_get(1HA), hatimerun(1M), pmfadm(1M), scrgadm(1M), scstat(1M), scswitch(1M), signal(3HEAD), rt_reg(4), attributes(5), r_properties(5), scalable_service(5)
Sun Cluster 3.0 Data Services Installation and Configuration
Guide
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| Sun Cluster 3.1 | Go To Top | Last Changed 01 Mar 2002 |
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