Brief Introduction to resource groups in hacmp

Brief Introduction to resource groups in hacmp!
For reference only !!

Brief Introduction to resource groups in Ha

 

Definition and settings of resource groups in the old version of hacmp

 

Cascading Resource Group

 

For multiple nodes with low resource configuration for some nodes, cascading type resource groups are suitable. Low-configuration nodes only temporarily replace high-configuration nodes, this satisfies the customer's cost-effective requirements.

Cascading resource groups assign different priorities to each node so that nodes with higher priorities can use resources. Some parameter settings:

 

Inactive
Takeover: If this parameter is set to false, the startup node does not request resources if it does not have the highest permission. Only the node with the highest permission requests resources. If this parameter is set to true
The started node will request resources. If the node to be added has higher permissions, the node will release the resources to the added node. Set to true.

 

Cascading
Fallback: If this parameter is set to true, the node does not request resources even if the recovered or added node has a higher priority. That is, the resource will not be fallback back to the high-priority node, as shown in figure
If the resource needs to be switched, stop the node using the takeover method. When this parameter is set to false, if the recovered or added node has a higher priority, the node will request the resource, that is, the resource.
Fallback is returned to the high-priority node. Generally, this parameter is set to false.

 

Note: These two parameters are common and need to be considered comprehensively.

 

Graceful: Stop a node and release resources. The active node does not take over.

Force: stops nodes and does not release resources.

Takeover: Stop a node, release resources, and take over resources from an active node.

 

Rotating Resource Group

 

For all nodes in the resource group, each node can only request one resource (the same network) until all resource requests are completed and other nodes are used as standby. When a node fails
If the takeover mode is disabled, the Standby node with the highest priority takes over the resources. When the failed node joins the cluster again, it does not apply for resources, but is used only as a standby Node
.

 

Concurrent Resource Group

 

The Resource Group can be shared by multiple nodes at the same time. Resources in the parallel Resource Group can only be volumes required by bare devices, bare disks, and application services. When a node fails, takeover does not occur. When the node is added again, it can continue to access resources in parallel.

 

The new version of hacmp (5.2) does not support the above three types of resource groups, and only supports the custom type of resource groups.

The following table lists the startup, fallover, and fallback policies available for hacm resource groups in hacmp 5.2:

Startup
Configurable policies include:

• Online on home node only. The resource group shoshould be brought
Online only on its home (highest priority) node during the resource
Group startup. This requires the highest priority node to be available.

• Online on first available node. The resource group activates on the first participant ipating node that becomes available.

• Online on all available nodes. The resource group is brought online on all nodes.

• Online using distribution policy. Only one resource group is
Brought online on a node, or on a node per network, depending on
Distribution policy specified (node or network ).
 
Fallover
Configurable policies include:

• Fallover to next priority node in the list. In the case
Fallover, the resource group that is online on only one node at a time
Follows the default node priority order specified in the Resource
Group's nodelist.

• Fallover using dynamic node priority. Before selecting this
Option, configure a dynamic node priority policy that you want to use.
Or you can select one of the three predefined dynamic node priority
Policies.

• Bring offline (on error node only). Select this option to bring a Resource Group offline on a node during an error condition.
 
Fallback
Configurable policies include:

• Fallback to higher priority node in the list. A Resource Group
Falls back when a higher priority node joins the cluster. If you select
This option, you can use the delayed fallback timer. If you do not
Configure a delayed fallback policy, the Resource Group falls back
Immediately when a higher priority node joins the cluster.

• Never fallback. A Resource Group does not fall back when a higher priority node joins the cluster.

 

Relationship between cascading, rotating, concurrent, and m

 

Definition of Resource Group before hacmp5.2
Definition of Resource Group in hacmp5.2
 
Cascading Resource Group

Inactive takeover = false

Cascading without fallback (cwof) = false

 
• Startup: online on home node only

• Fallover: fallover to next priority node in the list

• Fallback: fallback to higher priority node in the list
 
Cascading Resource Group

Inactive takeover = true

Cwof = false
• Startup: online on first available Node

Fallover: fallover to next priority node in the list

• Fallback: fallback to higher priority node in the list
 
Cascading Resource Group

Inactive takeover = false

Cwof = true
• Startup: online on home node only

• Fallover: fallover to next priority node in the list

• Fallback: Never fallback
 
Cascading Resource Group

Inactive takeover = true

Cwof = true
• Startup: online on Fisrt available Node

• Fallover: fallover to next priority node in the list

• Fallback: Never fallback
 
Rotating Resource Group
. Startup: online using distribution policy

• Resource Group distribution policy: network distribution

• Fallover: next priority node in the list

• Fallback: Never fallback
 
Concurrent Resource Group
• Startup: online on all available nodes

• Fallover: Bring offline (on error node only)

• Fallback: Never fallback