Installing the RHEV-M management console is not only the first step to configuring a hypervisor and virtual hosts, it also allows you to create virtual machines (VMs) in Red Hat Enterprise Virtualization 3.0.
RHEV 3.0 includes direct-attached storage (DAS), an updated graphical user interface and a new Web Admin Portal you can access at port 8080 of the RHEV-M server. The portal has the flexibility to run on any browser and lets you create VMs from a single interface. It's an unsupported tech preview in this version, but doesn't seem to be problematic, so I recommend you try it.
Let's take a look at the process of creating and installing a VM from the Web Admin Portal.
Installing the VM: The first steps
To install VMs in RHEV 3.0, copy the ISO file to the Linux file system of the RHEV-M server. Determine which directory you need to use by clicking on the Storage tab and then selecting the General tab at the bottom of the screen. You'll see the Network File System export path, which indicates which directory stores ISO files.
After copying the ISO file, you can begin to install the VM. Click New Server to begin. On the General tab, specify generic properties of the VM, starting with the operating system (OS). This, in turn, preselects relevant options for that OS.
Other required parameters include name, description and the amount of memory you want to assign to the host. On the Console tab, indicate which remote access protocol you want to use and whether you want to use USB devices with the VM. For more efficient console access to the VM, choose the SPICE remote access protocol, which is faster than virtual network computing.
On the Host tab, specify which server you want to host the VM, or select the option for any host in the cluster. In Run/Migration Options, choose properties that dictate how a VM migrates. To maintain flexibility, choosing none of these options will ensure the VM can live-migrate at any time.
To manage the VM with high availability, you must first set up RHEV HA and then elect the Highly Available option on the High Availability tab. You can also assign priority to the VM, which helps in the event of a disaster. If RHEV needs to start VMs on another host, it will first focus on high-priority VMs before migrating others.
Under the Resource Allocation tab, you can set the amount of guaranteed available memory for the VM. This option allows RHEV 3.0 to over-allocate memory while still guaranteeing that a host will never run out of the resources it needs. After specifying these memory allocation parameters, click OK to proceed.
Configuring the VM: The final steps
On the Boot Options link, specify the CD-ROM from which the VM will boot. Click on Attach CD and select the ISO you want to use from the list. You must complete this step first or you will not be able to continue the installation later.
At this point, the wizard stops but the VM still needs a virtual disk. Select the VM in the RHEV main window and then click on Virtual Disks tab.
Under that tab, click New and enter the disk properties, including the size. Under the Format option, choose either a pre-allocated disk (faster and recommended for servers) or thin provisioning, which allows for more efficient use of disk space and is recommended for desktops.
When you choose an interface, specify the VirtIO format, which gives you optimal disk performance. This driver, also called a paravirtualized driver, is optimized for use in a RHEV environment. With this driver, the VM can address physical hardware directly. Use the alternative option (IDE always works) only if the VirtIO option is unavailable. On legacy OSes, the driver may be unavailable if it has not been developed for that OS version.
Once RHEV-M has created the VM and you start it, right-click on the VM from the Web Admin Portal and select the Console option for Console access to the VM. Console access allows administrators to work directly on the console, as if they were sitting behind the VM.
Following these steps to customize VMs with specific parameters will better prepare you to manage an RHEV infrastructure and safeguard against potential disasters.
This was first published in October 2012