CST 6320: Data Visualization Project # 1: Research, Writing Essay & Presentation Points: 100 In this project, you will be performing extensive research on a contemporary visualization topic, summarize...

90547 - virtualization/ppt.pptx
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Contemporary Virtualization
Introduction
There has been recent resurgence in the popularity of virtualization.
It has resulted in higher number of usage.
There is need of high-performance network.
The efficiency of the virtualization will have impact on the multiple network servers which can have effect on the single physical machine.
The modern network visualization techniques have significant overhead.
It effects the achievable network performance.
The recent resurgence in popularity of virtualization has led to its use in a growing number of contexts, many of which require high-performance networking. Consider server consolidation, for example. The efficiency of network virtualization directly impacts the number of network servers that can effectively be consolidated onto a single physical machine. Unfortunately, modern network virtualization techniques incur significant overhead, which limits the achievable network performance. We need new network virtualization techniques to realize the full benefits of virtualization in network-intensive domains.
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It is important that the virtual machine monitor is able to accomplish the two key tasks for sharing network interface among multiple virtual machines.
The VMM is responsible for providing access in shared mode to the network interface.
The outflow of the network traffic should be multiplexed before sending it to the network.
All the incoming network traffic should be demultiplexed before delivering it to the appropriate virtual machine.
Second says that VMM should protect the virtual machines present in the network. It means that any of the virtual machine will not be allowed for transferring the data into or out the memory of another virtual.
To share a network interface among a set of virtual machines, the VMM (virtual machine monitor) must accomplish two key tasks. First, the VMM must provide shared access to the network interface. This means that the virtual machines’ outgoing network traffic must be multiplexed together before being sent over the network; similarly, incoming network traffic must be demultiplexed before being delivered to the appropriate virtual machines. Second, the VMM must protect the virtual machines from each other. This means that no virtual machine can be allowed to transfer data into or out of another virtual machine’s memory. Therefore, the challenge in network virtualization is to provide efficient, shared, and protected access to the network interface.
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Private I/O Devices
IBM’s System/360 was the first widely available virtualization solution.1 The System/370 extended the virtualization support for processors and memory but continued to use the same mechanisms as the System/360 for I/O virtualization.2 The initial I/O virtualization architectures developed for these systems did not permit shared access to physical I/O resources. Instead, physical I/O devices, such as terminals, were assigned exclusively to a particular virtual machine.
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The most common solution for virtualization was provided by IBM which was known as the System/360.
The system/370 was able to extend the virtualization support for the memory and processors but it was using the same mechanism as present in system/360 for the I/O virtualization.
The initial architecture which was used for the system did not allow the shared access for physical I/O resources.
The physical I/O devices like terminals were used for particular virtual machine.
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The channel programs used programmed I/O to transfer data between memory and the I/O device. On a virtualized system, the channel programs were executed inside the VMM, allowing the VMM to ensure that a virtual machine could access only its own memory and devices. More recent virtualization systems have also relied on private device access, such as IBM’s first release of the LPAR (logical partitioning) architecture for its Power4 processors.3 The Power4 architecture isolated devices at the PCI-slot level and assigned them to a particular virtual machine instance for management. Each virtual machine required a physically distinct disk controller for disk access and a physically distinct network interface for network access.
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The channel programs were using programmed I/O for transferring the data between I/O device and memory.
When we are working with the virtualized data, the channel programs will be executed inside the VMM.
It will allow the VMM to make sure that virtual machine is able to access only the memory and devices assigned to it.
Modern I/O Devices
Modern I/O devices use DMA (direct memory access) instead of programmed I/O, so it is not possible for the VMM to perform I/O data transfers. Instead, the Power4 LPAR architecture uses an IOMMU (I/O memory management unit) to restrict the memory that can be accessed by each device. To use an IOMMU in this manner, the VMM creates an I/O page table for each device, with memory mappings for the pages owned by the virtual machine to which that device is assigned. The IOMMU then consults the appropriate page table for every DMA operation. If a device tries to access memory without a valid mapping in its I/O page table, then the IOMMU will disallow the access.
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The modern I/O devices are using direct memory access instead of the programmed I/O.
It is not possible for the VMM to transfer the I/O data.
Power4 LPAR architecture uses the I/O memory management unit for restricting the memory which can be accessed by every connected device.
The VMM can create I/O page table for every device and IOMMU can be used.
IOMMU will consult the appropriate page table to perform DMA operation.
Benefits and drawbacks
The private I/O access has multiple benefits and the drawbacks.
It helps to achieve the performance of I/O access as each of the virtual machine is able to communicate directly with the physical device which it owns.
It is a very costly solution.
It needs the replicated physical devices for every virtual machine.
These device are underutilized, and it is impossible to include the enough number of the devices for the systems which have large number of virtual machines.
Private I/O access has obvious benefits and drawbacks. It yields high-performance I/O access, as each virtual machine can communicate directly with the physical devices that it owns. It is a costly solution, however, since it requires replicated physical devices for each virtual machine. These devices are likely to be underutilized, and for systems with large numbers of virtual machines it may be impossible to include a sufficient number of devices.
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Shared I/O Devices
A good way to decrease the costs inherent in providing private I/O devices is to allow I/O devices to be shared among virtual machines. The first shared I/O virtualization solutions were part of the networking support for System/360 and System/370 between physically separated virtual machines.4 This networking architecture supported shared access to the network using a virtualized spool-file interface that was serviced by a special-purpose virtual machine, or I/O domain, dedicated to networking.
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It is good manner for decreasing the cost to provide private I/O devices as it will allow the sharing of I/O devices among the virtual machines.
The first shared I/O virtualization solution was part of the networking support to the system/370 and system/360 present between the physically separated virtual machines.
This architecture is able to support shared access for the network with the help of virtualized spool file interface which was service by the special...