Contents
Abstract
To configure and manage cluster resources, either use the graphical user
interface (the Pacemaker GUI) or the crm command line
utility. For the command line approach, refer to
Chapter 6, Configuring and Managing Cluster Resources (Command Line).
This chapter introduces the Pacemaker GUI and covers basic tasks needed when configuring and managing cluster resources: creating basic and advanced types of resources (groups and clones), configuring constraints, specifying failover nodes and failback nodes, configuring resource monitoring, starting, cleaning up or removing resources, and migrating resources manually.
Support for the GUI is provided by two packages: The
pacemaker-mgmt package
contains the back-end for the GUI (the
mgmtd daemon). It must be
installed on all cluster nodes you want to connect to with the GUI. On
any machine where you want to run the GUI, install the
pacemaker-mgmt-client
package.
To start the Pacemaker GUI, enter crm_gui at the command line. To access the configuration and administration options, you need to log in to a cluster.
![[Note]](admon/note.png) | User Authentication |
|---|---|
To log in to the cluster from the Pacemaker GUI, the respective user must be
a member of the
Before using the Pacemaker GUI, either set a password for the
Do this on every node you will connect to with the Pacemaker GUI. | |
To connect to the cluster, select +. By
default, the field shows the localhost's IP
address and hacluster as . Enter the user's password to continue.
If you are running the Pacemaker GUI remotely, enter the IP address of a
cluster node as . As , you can also use any other user belonging to the
haclient group to connect to the cluster.
After being connected, the main window opens:
To view or modify cluster components like the CRM, resources, nodes or constraints, select the respective subentry of the category in the left pane and use the options that become available in the right pane. Additionally, the Pacemaker GUI lets you easily view, edit, import and export XML fragments of the CIB for the following subitems: , , , , and . Select any of the subitems and select + in the upper right corner of the window.
If you have already configured your resources, click the
category in the left pane to show the
status of your cluster and its resources. This view also allows you to
set nodes to standby and to modify the management
status of nodes (if they are currently managed by the cluster or not).
To access the main functions for resources (starting, stopping, cleaning
up or migrating resources), select the resource in the right pane and
use the icons in the toolbar. Alternatively, right-click the resource
and select the respective menu item from the context menu.
The Pacemaker GUI also allows you to switch between different view modes, influencing the behavior of the software and hiding or showing certain aspects:
- Simple Mode
Lets you add resources in a wizard-like mode. When creating and modifying resources, shows the frequently-used tabs for sub-objects, allowing you to directly add objects of that type via the tab.
Allows you to view and change all available global cluster options by selecting the entry in the left pane. The right pane then shows the values that are currently set. If no specific value is set for an option, it shows the default values instead.
- Expert Mode
Lets you add resources in either a wizard-like mode or via dialog windows. When creating and modifying resources, only shows the corresponding tab if a particular type of sub-object already exists in CIB. When adding a new sub-object, you will prompted to select the object type, thus allowing you to add all supported types of sub-objects.
When selecting the entry in the left pane, only shows the values of global cluster options that have been actually set. Hides all cluster options that will automatically use the defaults (because no values have been set). In this mode, the global cluster options can only be modified by using the individual configuration dialogs.
- Hack Mode
Has the same functions as the expert mode. Allows you to add additional attribute sets that include specific rules to make your configuration more dynamic. For example, you can make a resource have different instance attributes depending on the node it is hosted on. Furthermore, you can add a time-based rule for a meta attribute set to determine when the attributes take effect.
The window's status bar also shows the currently active mode.
The following sections guide you through the main tasks you need to execute when configuring cluster options and resources and show you how to administer the resources with the Pacemaker GUI. Where not stated otherwise, the step-by-step instructions reflect the procedure as executed in the simple mode.
Global cluster options control how the cluster behaves when confronted with certain situations. They are grouped into sets and can be viewed and modified with the cluster management tools like Pacemaker GUI and crm shell. The predefined values can be kept in most cases. However, to make key functions of your cluster work correctly, you need to adjust the following parameters after basic cluster setup:
Procedure 5.1. Modifying Global Cluster Options
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Select +.
In the left pane, select to view the global cluster options and their current values.
Depending on your cluster requirements, set to the appropriate value.
If you need to disable fencing for any reasons, deselect
Stonith Enabled.Confirm your changes with .
You can at any time switch back to the default values for all options by selecting in the left pane and clicking .
As a cluster administrator, you need to create cluster resources for every resource or application you run on servers in your cluster. Cluster resources can include Web sites, e-mail servers, databases, file systems, virtual machines, and any other server-based applications or services you want to make available to users at all times.
For an overview of resource types you can create, refer to Section 4.2.3, “Types of Resources”.
To create the most basic type of a resource, proceed as follows:
Procedure 5.2. Adding Primitive Resources
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the left pane, select and click +.
In the next dialog, set the following parameters for the resource:
Enter a unique for the resource.
From the list, select the resource agent class you want to use for that resource: , , or . For more information, see Section 4.2.2, “Supported Resource Agent Classes”.
If you selected as class, specify also the of your OCF resource agent. The OCF specification allows multiple vendors to supply the same resource agent.
From the list, select the resource agent you want to use (for example, or ). A short description for this resource agent is displayed below.
The selection you get in the list depends on the (and for OCF resources also on the ) you have chosen.
Below , set the .
Activate if you want the cluster to monitor if the resource is still healthy.
Click . The next window shows a summary of the parameters that you have already defined for that resource. All required for that resource are listed. You need to edit them in order to set them to appropriate values. You may also need to add more attributes, depending on your deployment and settings. For details how to do so, refer to Procedure 5.3, “Adding or Modifying Meta and Instance Attributes”.
If all parameters are set according to your wishes, click to finish the configuration of that resource. The configuration dialog is closed and the main window shows the newly added resource.
During or after creation of a resource, you can add or modify the following parameters for resources:
Instance attributes—they determine which instance of a service the resource controls. For more information, refer to Section 4.2.6, “Instance Attributes”.Meta attributes—they tell the CRM how to treat a specific resource. For more information, refer to Section 4.2.5, “Resource Options (Meta Attributes)”.Operations—they are needed for resource monitoring. For more information, refer to Section 4.2.7, “Resource Operations”.
Procedure 5.3. Adding or Modifying Meta and Instance Attributes
In the Pacemaker GUI main window, click in the left pane to see the resources already configured for the cluster.
In the right pane, select the resource to modify and click (or double-click the resource). The next window shows the basic resource parameters and the , or already defined for that resource.
To add a new meta attribute or instance attribute, select the respective tab and click .
Select the of the attribute you want to add. A short is displayed.
If needed, specify an attribute . Otherwise the default value of that attribute will be used.
Click to confirm your changes. The newly added or modified attribute appears on the tab.
If all parameters are set according to your wishes, click to finish the configuration of that resource. The configuration dialog is closed and the main window shows the modified resource.
![[Tip]](admon/tip.png) | XML Source Code for Resources |
|---|---|
The Pacemaker GUI allows you to view the XML fragments that are generated from the parameters that you have defined. For individual resources, select + in the top right corner of the resource configuration dialog. To access the XML representation of all resources that you have configured, click in the left pane and then select + in the upper right corner of the main window. The editor displaying the XML code allows you to or the XML elements or to manually edit the XML code. | |
To configure fencing, you need to configure one or more STONITH resources.
Procedure 5.4. Adding a STONITH Resource
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the left pane, select and click +.
In the next dialog, set the following parameters for the resource:
Enter a unique for the resource.
From the list, select the resource agent class .
From the list, select the STONITH plug-in for controlling your STONITH device. A short description for this plug-in is displayed below.
Below , set the .
Activate if you want the cluster to monitor the fencing device. For more information, refer to Section 9.4, “Monitoring Fencing Devices”.
Click . The next window shows a summary of the parameters that you have already defined for that resource. All required for the selected STONITH plug-in are listed. You need to edit them in order to set them to appropriate values. You may also need to add more attributes or monitor operations, depending on your deployment and settings. For details how to do so, refer to Procedure 5.3, “Adding or Modifying Meta and Instance Attributes” and Section 5.3.7, “Configuring Resource Monitoring”.
If all parameters are set according to your wishes, click to finish the configuration of that resource. The configuration dialog is closed and the main window shows the newly added resource.
To complete your fencing configuration add constraints, or use clones or both. For more details, refer to Chapter 9, Fencing and STONITH.
Having all the resources configured is only part of the job. Even if the cluster knows all needed resources, it might still not be able to handle them correctly. Resource constraints let you specify which cluster nodes resources can run on, what order resources will load, and what other resources a specific resource is dependent on.
For an overview which types of constraints are available, refer to Section 4.4.1, “Types of Constraints”. When defining constraints, you also need to specify scores. For more information about scores and their implications in the cluster, see Section 4.4.2, “Scores and Infinity”.
Learn how to create the different types of the constraints in the following procedures.
Procedure 5.5. Adding or Modifying Locational Constraints
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the Pacemaker GUI main window, click in the left pane to see the constraints already configured for the cluster.
In the left pane, select and click .
Select and click .
Enter a unique for the constraint. When modifying existing constraints, the ID is already defined and is displayed in the configuration dialog.
Select the for which to define the constraint. The list shows the IDs of all resources that have been configured for the cluster.
Set the for the constraint. Positive values indicate the resource can run on the you specify below. Negative values indicate the resource cannot run on this node. Values of
+/- INFINITYchange “can” tomust.Select the for the constraint.
If you leave the and the field empty, you can also add rules by clicking +. To add a lifetime, just click +.
If all parameters are set according to your wishes, click to finish the configuration of the constraint. The configuration dialog is closed and the main window shows the newly added or modified constraint.
Procedure 5.6. Adding or Modifying Collocational Constraints
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the Pacemaker GUI main window, click in the left pane to see the constraints already configured for the cluster.
In the left pane, select and click .
Select and click .
Enter a unique for the constraint. When modifying existing constraints, the ID is already defined and is displayed in the configuration dialog.
Select the which is the collocation source. The list shows the IDs of all resources that have been configured for the cluster.
If the constraint cannot be satisfied, the cluster may decide not to allow the resource to run at all.
If you leave both the and the field empty, you can also add a resource set by clicking +. To add a lifetime, just click +.
In , define the collocation target. The cluster will decide where to put this resource first and then decide where to put the resource in the field.
Define a to determine the location relationship between both resources. Positive values indicate the resources should run on the same node. Negative values indicate the resources should not run on the same node. Values of
+/- INFINITYchangeshouldtomust. The score will be combined with other factors to decide where to put the resource.If needed, specify further parameters, like .
Depending on the parameters and options you choose, a short explains the effect of the collocational constraint you are configuring.
If all parameters are set according to your wishes, click to finish the configuration of the constraint. The configuration dialog is closed and the main window shows the newly added or modified constraint.
Procedure 5.7. Adding or Modifying Ordering Constraints
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the Pacemaker GUI main window, click in the left pane to see the constraints already configured for the cluster.
In the left pane, select and click .
Select and click .
Enter a unique for the constraint. When modifying existing constraints, the ID is already defined and is displayed in the configuration dialog.
With , define the resource that must be started before the resource specified with is allowed to.
With define the resource that will start after the resource.
Depending on the parameters and options you choose, a short explains the effect of the ordering constraint you are configuring.
If needed, define further parameters, for example:
Specify a . If greater than zero, the constraint is mandatory, otherwise it is only a suggestion. The default value is
INFINITY.Specify a value for . If
true, the resources are stopped in the reverse order. The default value istrue.
If all parameters are set according to your wishes, click to finish the configuration of the constraint. The configuration dialog is closed and the main window shows the newly added or modified constraint.
You can access and modify all constraints that you have configured in the view of the Pacemaker GUI.
A resource will be automatically restarted if it fails. If that cannot
be achieved on the current node, or it fails N times on the current
node, it will try to fail over to another node. You can define a number
of failures for resources (a migration-threshold),
after which they will migrate to a new node. If you have more than two
nodes in your cluster, the node a particular resource fails over to is
chosen by the High Availability software.
However, you can specify the node a resource will fail over to by proceeding as follows:
Configure a location constraint for that resource as described in Procedure 5.5, “Adding or Modifying Locational Constraints”.
Add the
migration-thresholdmeta attribute to that resource as described in Procedure 5.3, “Adding or Modifying Meta and Instance Attributes” and enter a for the migration-threshold. The value should be positive and less that INFINITY.If you want to automatically expire the failcount for a resource, add the
failure-timeoutmeta attribute to that resource as described in Procedure 5.3, “Adding or Modifying Meta and Instance Attributes” and enter a for the failure-timeout.If you want to specify additional failover nodes with preferences for a resource, create additional location constraints.
For an example of the process flow in the cluster regarding migration thresholds and failcounts, see Example 4.2, “Migration Threshold—Process Flow”.
Instead of letting the failcount for a resource expire automatically, you can also clean up failcounts for a resource manually at any time. Refer to Section 5.4.2, “Cleaning Up Resources” for the details.
A resource might fail back to its original node when that node is back online and in the cluster. If you want to prevent a resource from failing back to the node it was running on prior to failover, or if you want to specify a different node for the resource to fail back to, you must change its resource stickiness value. You can either specify resource stickiness when you are creating a resource, or afterwards.
For the implications of different resource stickiness values, refer to Section 4.4.4, “Failback Nodes”.
Procedure 5.8. Specifying Resource Stickiness
Add the
resource-stickinessmeta attribute to the resource as described in Procedure 5.3, “Adding or Modifying Meta and Instance Attributes”.
As for the resource-stickiness, specify a value between
-INFINITYandINFINITY.
Not all resources are equal. Some, such as Xen guests, require that the node hosting them meets their capacity requirements. If resources are placed such that their combined need exceed the provided capacity, the resources diminish in performance (or even fail).
To take this into account, the High Availability Extension allows you to specify the following parameters:
The capacity a certain node provides.
The capacity a certain resource requires.
An overall strategy for placement of resources.
For detailed background information about the parameters and a configuration example, refer to Section 4.4.5, “Placing Resources Based on Their Load Impact”.
To configure the resource's requirements and the capacity a node provides, use utilization attributes as described in Procedure 5.9, “Adding Or Modifying Utilization Attributes”. You can name the utilization attributes according to your preferences and define as many name/value pairs as your configuration needs.
Procedure 5.9. Adding Or Modifying Utilization Attributes
In the following example, we assume that you already have a basic configuration of cluster nodes and resources and now additionally want to configure the capacities a certain node provides and the capacity a certain resource requires. The procedure of adding utilization attributes is basically the same and only differs in Step 2 and Step 3.
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
To specify the capacity a node provides:
In the left pane, click .
In the right pane, select the node whose capacity you want to configure and click .
To specify the capacity a resource requires:
In the left pane, click .
In the right pane, select the resource whose capacity you want to configure and click .
Select the tab and click to add an utilization attribute.
Enter a for the new attribute. You can name the utilization attributes according to your preferences.
Enter a for the attribute and click . The attribute value must be an integer.
If you need more utilization attributes, repeat Step 5 to Step 6.
The tab shows a summary of the utilization attributes that you have already defined for that node or resource.
If all parameters are set according to your wishes, click to close the configuration dialog.
Figure 5.4, “Example Configuration for Node Capacity” shows the configuration of a node which would provide 8 CPU units and 16 GB of memory to resources running on that node:
An example configuration for a resource requiring 4096 memory units and 4 of the CPU units of a node would look as follows:
After you have configured the capacities your nodes provide and the capacities your resources require, you need to set the placement strategy in the global cluster options, otherwise the capacity configurations have no effect. Several strategies are available to schedule the load: for example, you can concentrate it on as few nodes as possible, or balance it evenly over all available nodes. For more information, refer to Section 4.4.5, “Placing Resources Based on Their Load Impact”.
Procedure 5.10. Setting the Placement Strategy
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Select +.
In the left pane, select to view the global cluster options and their current values.
Depending on your requirements, set to the appropriate value.
If you need to disable fencing for any reasons, deselect
Stonith Enabled.Confirm your changes with .
Although the High Availability Extension can detect a node failure, it also has the ability
to detect when an individual resource on a node has failed. If you want
to ensure that a resource is running, you must configure resource
monitoring for it. Resource monitoring consists of specifying a timeout
and/or start delay value, and an interval. The interval tells the CRM
how often it should check the resource status. You can also set
particular parameters, such as Timeout for
start or stop operations.
Procedure 5.11. Adding or Modifying Monitor Operations
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the Pacemaker GUI main window, click in the left pane to see the resources already configured for the cluster.
In the right pane, select the resource to modify and click . The next window shows the basic resource parameters and the meta attributes, instance attributes and operations already defined for that resource.
To add a new monitor operation, select the respective tab and click .
To modify an existing operation, select the respective entry and click .
In , select the action to perform, for example
monitor,start, or .The parameters shown below depend on the selection you make here.
In the field, enter a value in seconds. After the specified timeout period, the operation will be treated as
failed. The PE will decide what to do or execute what you specified in the field of the monitor operation.If needed, expand the section and add parameters, like (what to do if this action ever fails?) or (what conditions need to be satisfied before this action occurs?).
If all parameters are set according to your wishes, click to finish the configuration of that resource. The configuration dialog is closed and the main window shows the modified resource.
For the processes which take place if the resource monitor detects a failure, refer to Section 4.3, “Resource Monitoring”.
To view resource failures in the Pacemaker GUI, click in the left pane, then select the resource whose details you want to see in the right pane. For a resource that has failed, the and last failure of the resource is shown in the middle of the right pane (below the entry).
Some cluster resources are dependent on other components or resources, and require that each component or resource starts in a specific order and runs together on the same server. To simplify this configuration we support the concept of groups.
For an example of a resource group and more information about groups and their properties, refer to Section 4.2.4.1, “Groups”.
| Empty Groups |
|---|---|
Groups must contain at least one resource, otherwise the configuration is not valid. | |
Procedure 5.12. Adding a Resource Group
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the left pane, select and click +.
Enter a unique for the group.
Below , set the and click .
In the next step, you can add primitives as sub-resources for the group. These are created similar as described in Procedure 5.2, “Adding Primitive Resources”.
If all parameters are set according to your wishes, click to finish the configuration of the primitive.
In the next window, you can continue adding sub-resources for the group by choosing again and clicking .
When you do not want to add more primitives to the group, click instead. The next window shows a summary of the parameters that you have already defined for that group. The and of the group are listed. The position of the resources in the tab represents the order in which the resources are started in the cluster.
As the order of resources in a group is important, use the and buttons to sort the in the group.
If all parameters are set according to your wishes, click to finish the configuration of that group. The configuration dialog is closed and the main window shows the newly created or modified group.
Let us assume you already have created a resource group as explained in Procedure 5.12, “Adding a Resource Group”. The following procedure shows you how to modify the group to match Example 4.1, “Resource Group for a Web Server”.
Procedure 5.13. Adding Resources to an Existing Group
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the left pane, switch to the view and in the right pane, select the group to modify and click . The next window shows the basic group parameters and the meta attributes and primitives already defined for that resource.
Click the tab and click .
In the next dialog, set the following parameters to add an IP address as sub-resource of the group:
Enter a unique (for example,
my_ipaddress).From the list, select as resource agent class.
As of your OCF resource agent, select .
From the list, select as resource agent.
Click .
In the tab, select the entry and click (or double-click the entry).
As , enter the desired IP address, for example,
192.168.1.1.Click and . The group configuration dialog shows the newly added primitive.
Add the next sub-resources (file system and Web server) by clicking again.
Set the respective parameters for each of the sub-resources similar to steps Step 4.a to Step 4.h, until you have configured all sub-resources for the group.
As we configured the sub-resources already in the order in that they need to be started in the cluster, the order on the tab is already correct.
In case you need to change the resource order for a group, use the and buttons to sort the resources on the tab.
To remove a resource from the group, select the resource on the tab and click .
Click to finish the configuration of that group. The configuration dialog is closed and the main window shows the modified group.
You may want certain resources to run simultaneously on multiple nodes in your cluster. To do this you must configure a resource as a clone. Examples of resources that might be configured as clones include STONITH and cluster file systems like OCFS2. You can clone any resource provided. This is supported by the resource’s Resource Agent. Clone resources may even be configured differently depending on which nodes they are hosted.
For an overview which types of resource clones are available, refer to Section 4.2.4.2, “Clones”.
Procedure 5.14. Adding or Modifying Clones
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
In the left pane, select and click +.
Enter a unique for the clone.
Below , set the .
Activate the respective options you want to set for your clone and click .
In the next step, you can either add a or a as sub-resources for the clone. These are created similar as described in Procedure 5.2, “Adding Primitive Resources” or Procedure 5.12, “Adding a Resource Group”.
If all parameters in the clone configuration dialog are set according to your wishes, click to finish the configuration of the clone.
Apart from the possibility to configure your cluster resources, the Pacemaker GUI also allows you to manage existing resources. To switch to a management view and to access the available options, click in the left pane.
Before you start a cluster resource, make sure it is set up correctly. For example, if you want to use an Apache server as a cluster resource, set up the Apache server first and complete the Apache configuration before starting the respective resource in your cluster.
| Do Not Touch Services Managed by the Cluster |
|---|---|
When managing a resource with the High Availability Extension, the same resource must not be started or stopped otherwise (outside of the cluster, for example manually or on boot or reboot). The High Availability Extension software is responsible for all service start or stop actions. However, if you want to check if the service is configured properly, start it manually, but make sure that it is stopped again before High Availability takes over.
For interventions in resources that are currently managed by the
cluster, set the resource to | |
During creation of a resource with the Pacemaker GUI, you can set the
resource's initial state with the target-role meta
attribute. If its value has been set to stopped, the
resource does not start automatically after being created.
Procedure 5.15. Starting A New Resource
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
In the right pane, right-click the resource and select from the context menu (or use the icon in the toolbar).
A resource will be automatically restarted if it fails, but each failure raises the resource's failcount. View a resource's failcount with the Pacemaker GUI my clicking in the left pane, then selecting the resource in the right pane. If a resource has failed, its is shown in the middle of the right pane (below the entry).
If a migration-threshold has been set for that
resource, the node will no longer be allowed to run the resource as soon
as the number of failures has reached the migration threshold.
A resource's failcount can either be reset automatically (by setting a
failure-timeout option for the resource) or you can
reset it manually as described below.
Procedure 5.16. Cleaning Up A Resource
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
In the right pane, right-click the respective resource and select from the context menu (or use the icon in the toolbar).
This executes the commands crm_resource
-Cand crm_failcount-Dfor the specified resource on the specified node.
For more information, see also crm_resource(8) and crm_failcount(8).
If you need to remove a resource from the cluster, follow the procedure below to avoid configuration errors:
| Removing Referenced Resources |
|---|---|
Cluster resources cannot be removed if their ID is referenced by any constraint. If you cannot delete a resource, check where the resource ID is referenced and remove the resource from the constraint first. | |
Procedure 5.17. Removing a Cluster Resource
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
Select the respective resource in the right pane.
Clean up the resource on all nodes as described in Procedure 5.16, “Cleaning Up A Resource”.
the resource.
Remove all constraints that relate to the resource, otherwise removing the resource will not be possible.
As mentioned in Section 5.3.4, “Specifying Resource Failover Nodes”, the cluster will fail over (migrate) resources automatically in case of software or hardware failures—according to certain parameters you can define (for example, migration threshold or resource stickiness). Apart from that, you can also manually migrate a resource to another node in the cluster resources manually.
Procedure 5.18. Manually Migrating a Resource
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
Right-click the respective resource in the right pane and select .
In the new window, select the node to which to move the resource to in . This creates a location constraint with an
INFINITYscore for the destination node.If you want to migrate the resource only temporarily, activate and enter the time frame for which the resource should migrate to the new node. After the expiration of the duration, the resource can move back to its original location or it may stay where it is (depending on resource stickiness).
In cases where the resource cannot be migrated (if the resource's stickiness and constraint scores total more than
INFINITYon the current node), activate the option. This forces the resource to move by creating a rule for the current location and a score of-INFINITY.This prevents the resource from running on this node until the constraint is removed with or the duration expires.
Click to confirm the migration.
To allow a resource to move back again, proceed as follows:
Procedure 5.19. Clearing a Migration Constraint
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
Right-click the respective resource in the right pane and select .
This uses the crm_resource
-Ucommand. The resource can move back to its original location or it may stay where it is (depending on resource stickiness).
For more information, see crm_resource(8) or Pacemaker 1.0—Configuration Explained, available from http://clusterlabs.org/wiki/Documentation. Refer to section Resource Migration.
When a resource is being managed by the cluster, it must not be touched
otherwise (outside of the cluster). For maintenance of individual
resources, you can set the respective resources to an unmanaged
mode that allows you to modify the resource outside of the
cluster.
Start the Pacemaker GUI and log in to the cluster as described in Section 5.1.1, “Connecting to a Cluster”.
Click in the left pane.
Right-click the respective resource in the right pane and from the context menu, select .
After you have finished the maintenance task for that resource, right-click the respective resource again in the right pane and select .
From this point on, the resource will be managed by the High Availability Extension software again.