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Virtualization Performance and Workload Recommendations to Get the Most From Your Assets

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Posted: 10 Aug 2007
 

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Virtualization Performance and Workload Recommendations to Get the Most From Your Assets

by Jason Williams
Novell Connection Magazine - Q3 2007

Here's an excerpt:

Novell Open Enterprise Server 2 has the ability to run in either a physical or virtual environment. Part of the Open Enterprise Server 2 product is SUSE Linux Enterprise Server 10 Support Pack 1 including Xen virtualization. This article will give you information and guidance about virtualization in Open Enterprise Server 2, so you can deploy a virtualized environment with confidence.

The subject of virtual machine technology is very broad. But we'll focus heavily on the benefits of a virtualized environment for Open Enterprise Server 2 using either Linux or NetWare.

>Virtual Machine technology overview
Virtual machine technology is not a new concept and has been available in the market for a number of years. First available on mainframe systems, it gradually made its way onto Personal Computers.

Virtualization has now made the transition into mainstream Network Operating systems such as Linux and Windows and is making significant strides into the data center. In Open Enterprise Server 2, the Virtual Machine technology is provided via the Xensource Xen 3.0 project integrated into SUSE Linux Enterprise Server 10.

Like most Virtual Machine technology, Xen 3.0 comprises a host (also known as DOMAIN 0) and multiple guests (also known as DOMAIN U). The host governs partitioning a physical server and assigning resources requested by each guest. When a guest machine is started and the operating system booted (such as NetWare), the host assigns physical resources to the guest.

Some resources (such as memory) are dedicated to the guest and cannot be shared between guest operating systems. Other resources, such as Network Interface Cards, can be shared between guest operating systems. Or if more than one physical resource is available, they can be dedicated to a specific guest. As more guest operating systems are started, more physical resources are assigned by the host as requested and required.

Xen 3.0 has an advantage over many of its counterparts as it incorporates a ?hypervisor? as part of the core virtualization layer. The hypervisor allows a modified guest operating system (such as NetWare or SUSE Linux Enterprise Server) to more efficiently interact with the physical server. This is known as ?para-virtualization.? Nonmodified guest operating systems (such as Windows) do not receive this benefit and operate in what is known as ?full? virtualization mode.

Despite the efficiencies recognized by the Xen hypervisor technology, there is still a performance ?tax? that must be paid in a virtual environment. Virtual machines that share a network card will be unable to use the full bandwidth available. Their overall throughput is governed by how many virtual machines are using the card at any one time and the relative network traffic that is generated. The same is also true of CPU resources. The amount of output you get depends on whether or not the server is running solely from a virtual disk image and how much overall memory the physical server has available.

Read the complete article here


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