Newsletters

According to expert predictions, mainframes were scheduled to be replaced by flocks of small servers years ago. It seems they never got the news. Rather than dying off, they have experienced a rebirth. And one key to their longevity has been virtualization. Developed in the 60s, logical partitioning (LPAR) allowed multiple processes to share the same set of mainframe hardware, resulting in far more efficient resource utilization.

A few years ago, VMware seized on this idea, creating software that allowed companies to run multiple instances of Windows, Unix and Linux to operate on a single x86 (Intel architecture) server and later on IBM zOS mainframes. Success breeds competition, and VMware's array of products has been joined by Microsoft's Virtual Server 2005, SWSoft's Virtuozzo, IBM's Virtualization Engine 2.0, Virtual Iron Software's Virtual Iron 2.0 and the open source Xen project. In addition, AMD and Intel are now building virtualization support into their CPUs.

But while virtualization is becoming ever more popular, it does bring its own set of challenges. Addressing these require the right set of management tools.

Top Reasons for Virtualization
Virtualization involves putting a separation layer between a process and the hardware it is running on. This makes it possible for multiple, heterogeneous operating systems to run on the same physical machine or group of machines. Over the past five years its popularity has grown to the point where it will soon be the default method of running a server. Among virtualization’s advantages are:

• Easier Provisioning. Virtualization allows simpler provisioning and sharing of server resources among numerous applications.
• Resource Reallocation. Virtualization makes it possible to shift server images from one set of equipment to another; either to balance workload for better efficiency, or when there is a hardware problem. This can take place automatically without operator intervention.
• Server Consolidation. Traditionally a server is sized to meet the greatest anticipated load for its application, plus some overhead for safety. Since servers typically run well below their peak in terms of CPU, memory or storage utilization, this results in a huge waste of computing resources. Virtualization lets companies consolidate the applications from a number of smaller servers onto a single larger system, cutting hardware, power and maintenance costs as well as freeing up floor or rack space.
• Quick Server Setup. When an additional instance of a server is needed, it is easy to create another image of an existing virtual machine and get it running. VMware's VirtualCenter administrative interface, for example, allows administrators to create and server configuration templates to deploy or modify as needed.
• Isolation. Applications can be isolated from one another while running on the same physical server.

Virtualization Challenges
While it has many advantages, virtualization also presents its own unique set of challenges. To begin with, different vendors offer their own version of how resources should be divided and managed. These are not necessarily compatible, which adds to the management load.

Then there is the matter of selecting which application to consolidate onto a given physical frame. Some may require heavy use of the CPU, others are I/O intensive or bandwidth hogs. It is also necessary to examine peak utilization periods so these don't conflict. All these factors, and more, must be considered to assemble the right mix of applications to run on a server.

Backing up virtual servers is also different than physical ones. Typically, backups are scheduled to run overnight, since they involve high resource utilization. But, whereas one might schedule a number of physically discrete servers to run during the same window, attempting to run a midnight backup simultaneously on twenty virtual servers sharing the same NIC is guaranteed to create a traffic jam. Specialized backup software is needed to manage the scheduling of multiple virtual machines sharing the same hardware.

Then there is the matter of determining operating system performance metrics regarding hardware, when the system image no longer represents the entire server workload.

TeamQuest and Virtualization
TeamQuest's management tools won't backup the servers, but they do make that problem easier, as well as addressing the other three listed above. Two years ago, the company added VMware support to each product in the TeamQuest Performance Software Suite:

• TeamQuest Manager has five collection agents for VMware ESX Server 2.0. Two of these gather CPU/disk/memory/NIC resource utilization from each of the virtual machines as well as the ESX service console. The others collect disk space, process-workload and system log messages from the service console. Administrators can then view the information regarding any of the individual virtual machines, or the server as a whole.
• TeamQuest View is the suite's analysis and investigation tool. With it, administrators can set up threshold alarms on the virtual machines, as well as the entire server, and then drill down into the users and virtual processes to determine the root cause before it starts impacting quality of service.
• The TeamQuest Model capacity planning and modeling tool works with both virtual and physical resources. Capacity planners can model each virtual machine as a workload and identify conflicts or bottlenecks. In addition to helping plan future hardware purchases, it lets administrators shuffle around virtual loads between different servers to determine the optimum workload on each box.
• TeamQuest on the Web - This application provides viewing and distribution of reports on VMware service console and virtual machine statistics.
• TeamQuest Alert treats alerts from the VMware the same as ones from physical servers.

TeamQuest's management tools give administrators the same level of visibility and control into their virtual servers as they do with their physical ones. In doing so, they bring the promise offered by virtualization one step closer to reality.