2.2.3. Cluster Related Entities

To configure the cluster, the related objects that belong to the cluster also need to be set up. Clusters allow you to better control the scheduling of virtual machines and to perform load balancing.
Cluster General Entities
You can define load-balancing policies for each of your clusters.

Table 2.7. Cluster General Tab Properties

Field/Tab
Description/Action
Policy
The Edit Policy dialog box allows an administrator to set load balancing policy for a cluster to define the number of virtual machines that will be started on each host in the cluster. Set the Policy value to None to have no load or power sharing between hosts. This is the default mode.
Maximum Service Level
Use Even Distribution to evenly distribute the processing load across all hosts in the cluster. The host's CPU load is measured and used to apply the policy. Use the blue slider to specify the Maximum Service Level a host is permitted to have. A host that has reached the maximum service level defined will not have further virtual machines started on it. You can also specify the time interval in minutes that a host is permitted to run at the maximum service level before virtual machines are migrated off it. Selecting an even distribution load balancing policy causes virtual machines to be started on alternate hosts in the cluster to ensure that the CPU load on each host in the cluster is even.
Minimum Service Level
Use Power Saving to automatically reduce power consumption on under-utilized hosts. The green slider to specifies the Minimum Service Level a host is permitted to have. When a host has reached the minimum service level defined, virtual machines are migrated to other hosts. An administrator can then power down the hosts with low usage levels to conserve power. You can also specify the time interval (in minutes) that a host is permitted to run at the minimum service level before the migrations of any remaining virtual machines are triggered.

Cluster Hosts Entities
A cluster is a collection of physical hosts that share the same storage domains and have the same type of CPU. The host tab displays all the information related to all the hosts in a cluster.

Table 2.8. Cluster Hosts Tab Properties

Field/Tab
Description/Action
Name
The name of the host.
Host/IP
The Host/IP address.
Status
The status of the host.
Load
The number of virtual machines in each host.

Cluster Virtual Machines Entities
The clusters in a data center are the migration domains for virtual machines. The ability to migrate virtual machines from one host to another in a host is a key feature of virtualization. Virtual machines can be migrated across hosts in the same cluster hence, the cluster is the highest level at which power and load-sharing policies can be defined. When upgrading the Manager, the clusters need to be upgraded before the data center can work in the upgraded Manager. The Virtual Machines tab displays all the information related to all the virtual machines in a cluster.

Table 2.9. Cluster Virtual Machines Tab Properties

Field/Tab
Description/Action
Name
The name of the virtual machine belonging to a host.
Status
The status of all the virtual machine running on different hosts.
Host
The name of the host that a virtual machine is running on.
Uptime
The amount of time that a virtual machine has been up.

Cluster Logical Networks Entities
Logical networks are required both for the virtual machines to communicate to hosts and storage, and for the Manager to communicate with all entities. Logical networks need to be defined for each cluster.

Table 2.10. Cluster Logical Networks Tab Properties

Field/Tab
Description/Action
Name
The name of the logical networks in a cluster.
Status
The status of the logical networks.
Role
The hierarchical permissions available to the logical network.
Description
The description of the logical networks.

Cluster Permissions Entities
Cluster permissions define which users and roles can work in a cluster, and what operations the users and roles can perform.

Table 2.11. Cluster Permissions Tab Properties

Field/Tab
Description/Action
User
The user name of an existing user in the directory services.
Role
The role of the user. The role comprises of user, permission level and object. Roles can be default or customized roles.
Inherited Permissions
The hierarchical permissions available to the user.