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Chapter 9. Planning your Data Center

9.1. Data Centers
9.1.1. Prerequisites for Setting up a Data Center
9.1.2. Working with Data Centers
9.1.3. Creating a New Data Center
9.2. Clusters
9.2.1. Creating a Cluster
Successful planning is essential for a highly available, scalable Red Hat Enterprise Virtualization environment.
Although it is assumed that your solution architect has defined the environment before installation, the following considerations must be made when designing the system.
CPU
Virtual Machines must be distributed across hosts so that enough capacity is available to handle higher than average loads during peak processing. Average target utilization will be 50% of available CPU.
Memory
The Red Hat Enterprise Virtualization page sharing process overcommits up to 150% of physical memory for virtual machines. Therefore, allow for an approximately 30% overcommit.
Networking
When designing the network, it is important to ensure that the volume of traffic produced by storage, remote connections and virtual machines is taken into account. As a general rule, allow approximately 50 MBps per virtual machine.
It is best practice to separate disk I/O traffic from end-user traffic, as this reduces the load on the Ethernet connection and reduces security vulnerabilities by isolating data from the visual stream. For Ethernet networks, it is suggested that bonds (802.3ad) are utilized to aggregate server traffic types.

Note

It is possible to connect both the storage and Hypervisors via a single high performance switch. For this configuration to be effective, the switch must be able to provide 30 GBps on the backplane.
High Availability
The system requires at least two hosts to achieve high availability. This redundancy is useful when performing maintenance or repairs.

9.1. Data Centers

Following Red Hat Enterprise Virtualization Manager installation it is necessary to define the data centers, and clusters, that you will use to organize your virtualization hosts. The installation process creates a data center, and associated cluster, called Default. The storage type of the data center is set based on the one selected during installation. If you wish to make use of other storage types then you will need to add additional data centers and clusters to support them.

9.1.1. Prerequisites for Setting up a Data Center

Before you create a new data center, prepare the following resources. The following tasks must be done at the host level, not from the Red Hat Enterprise Virtualization platform.
  1. Setup and configure hosts. A host can be a Red Hat Enterprise Virtualization Hypervisor or a Red Hat Enterprise Linux 6 host. A cluster needs a minimum of one host, and at least one active host is required to connect the system to a storage pool.
  2. Setup, configure and define storage. It is recommended that data centers have a minimum of two storage domains, one to store disk images of the virtual machines and one to store ISO images. Set up the storage domains of the type required for the data center; NFS, iSCSI, FCP or Local. For example, for an NFS data center, create and mount the export directories.
  3. Set up logical networks for the data center, cluster and the hosts. It is recommended that you have the IP addresses/domain names available for reference.

9.1.2. Working with Data Centers

This section describes how to configure, create and manage data centers. The data center is the highest level container for all physical and logical resources within a managed virtual environment. The data center is a collection of clusters of hosts. It owns the logical network (that is, the defined subnets for management, guest network traffic and storage network traffic) and the storage pool.
Data Centers
Figure 9.1. Data Centers

Red Hat Enterprise Virtualization contains a default data center at installation. Enterprises can set up new and additional data centers that can all be managed from the single Administration Portal. For example, an organization may have different data centers for different physical locations, business units, or for reasons of security. It is recommended that you do not remove the default data center, instead set up new appropriately named data centers.
The system administrator, as the superuser, can manage all aspects of the platform, that is, data centers, storage pools, users, roles and permissions by default; however more specific administrative roles and permissions can be assigned to other users. For example, the enterprise may need a data center administrator for a specific data center, or a particular cluster may need an administrator. All system administration roles for physical resources have a hierarchical permission system. For example, a data center administrator will automatically have permission to manage all the objects in that data center, storage, cluster and hosts; while a cluster administrator can manage all objects in the particular cluster.

9.1.3. Creating a New Data Center

A data center is a logical grouping of clusters of hosts. If you wish to create an additional data center, use the instructions in this section; if you wish to use the existing default data center then you may skip this process and begin creating clusters, see Section 9.2, “Clusters”.
The Data Centers tab displays a list of data centers.
Data Centers Tab
Figure 9.2. Data Centers Tab

  1. Click the New button on the Data Centers tab. The New Data Center dialog displays.
  2. Enter the Name and Description of the data center.
  3. Select the storage Type of the data center. Select the storage appropriate to your data center; one of the following:
    • NFS
    • iSCSI
    • FCP
    • Local Storage
  4. Select the Compatibility Level of the data center, 2.2 or 3.0.
  5. Click OK.
  6. The Guide Me dialog displays a list of configuration tasks that must be completed before the data center can be activated. The data center configuration tasks can be done immediately or later.
    New Data Center Guide Me Dialog
    Figure 9.3. New Data Center Guide Me Dialog

    Click Configure Later to close the dialog.
Result:
The new data center is added, and appears in appropriate searches or lists of data centers, with a status of Uninitialized. An uninitialized data center typically requires further configuration, for example, storage domains must be attached to it. Either click the Configure Storage button on the Guide Me dialog or select the new data center in the list, and click the Storage tab in the Details pane. You can define existing storage for the data center, or attach existing storage domains to the data center.