Managing Your Virtual World - Tech Focus November 2009 Part 2
Alan Le Marquand
In the previous post “ Managing your Microsoft world” the focus was on management of Windows Servers and the applications that run on them regardless of if they are physical machines or virtual machines. This post focuses more on the virtualization infrastructure and looking primarily at Hyper-V and System Center Virtual Machine Manager.
To recap the previous post, System Center Operations Manager 2007 R2 or System Center Essentials 2007 are not particular about whether the servers they are monitoring are physical or virtual; both products happily manage servers in either configuration. When you implement virtualization, management of these virtualized servers does not change from when they were physical; maintenance tasks still need to performed, albeit some are handled differently. An example is the task of ensuring there is enough space on the machine’s discs. For a physical server this could mean cleaning up or compressing old files, or buying a new disk. For virtual servers this may mean moving the VHD file to a different storage device so it can grow, or simply creating and add a new VHD file to the virtual machine.
In a single instance, the Hyper-V management console allows you to perform management tasks generally needed to keep the virtual machines running. More often than not, a virtualization rollout may require more than one Hyper-V server, it may even be part of a mixed environment with different virtualization technologies. For this situation, the ideal solution is to have a product that can manage a number virtualization instances.
The System Center range has such a product, System Center Virtual Machine Manager. SCVMM allows you to monitor multiple host machines, up to 400 on a single SCVMM server, from one console. Like the standard Hyper-V console, you can start and stop virtual machines, connect to them, create checkpoints, as well as move machines around. SCVMM also goes beyond the management capabilities of the Hyper-V console; it has the capability to manage both Virtual Server and VMWare Esx 3.5 update 2 servers, provide easy deployment of new virtual machines on demand, and help convert existing, physical serves to virtual machines. So let’s look at how SCVMM can assist administrators in managing a virtual environment.
As mentioned above, a lot of organizations will deploy more than one Hyper-V server. It is not advisable to put all your eggs in one basket, and they will look to these multiple servers to provide resiliency and balance. The trick in deploying multiple servers is to ensure the most efficient use of the server resources; SCVMM has the ability to help with that task using a feature called Intelligent Placement. Out-of-the box Intelligent Placement provides IT administrators the ability to select the appropriate host based on resource consumption information gathered by SCVMM. This information is incorporated into algorithms that can be tuned to improve resource utilization. If System Center Operations Manager (SCOM) is installed in the environment, it integrates with SCVMM to provide a richer set of capabilities that help administrators ensure their virtual machines are running at optimal levels. This feature is called Physical Resource Optimization (PRO), and it relies on PRO-enabled management packs being installed on SCOM. Just like SCOM, PRO can provide assistance to administrators through what are called PRO Tips. These can provide, via pop-up windows in the SCVMM console, information and remediation when specific thresholds are exceeded or other incidents occur. Administrators are then able to make decisions about the situation quickly and efficiently.
One of the benefits of virtualization is the ease in scaling up and down as needed. This technique is how Windows Azure delivers its services. A classic example is a retail web application, say for most of the year the web application runs happily on half a dozen servers, but at peak periods, like Christmas or Thanksgiving, or even during a promotional period, those half dozen servers are not enough to cope with demand. Without a virtualization solution you would have to have physical servers available to increase throughput. For arguments' sake, let’s say you need to double the capacity for the web application from half a dozen serves to a dozen. Outside those peak periods, what do you do with servers? Power them down? Repurpose them? So let’s now look at this example, but virtualized. Instead of 12 servers, we reduce that to 2 highly powered servers. We can run our 6 normal servers as virtual machines split across those two machines. When demand rises we provision a new virtual machine, when demand drops, we take the virtual machine offline.
Where SCVMM comes into this solution is the management of these virtual machines and two features in particular, the library feature and the Offline Servicing tool. SCVMM allows you to hold a library of files to enable rapid deployment of virtual machines. In our example above, a template of the web application can be stored in the library. As demand rises this template can be used to deploy a new instance of the web application. Because the image is stored as a template it can be controlled. This allows some of the responsibility of deploying the image to be passed on. SCVMM has a Self-Service web portal that can allow authorized users to create and manage their own machines. IT Administrators still maintain control over who can use the portal, but there are scenarios when the IT Department does not want to be continuously starting and stopping virtual machines.
One issue that both the virtual and physical solutions must address is maintenance of machines and images not currently running. For a physical machine, that involves powering it on and running the updates. In the virtual solution the Offline Virtual Machine Servicing Tool (OLVMST) performs this function. In both cases, the operating system has to be running for the update to take place. OLVMST does this by using a Maintenance host that is isola