Virtualization Technology Advantages And Disadvantages

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Recently, Virtualization technology proved out to be a big revolution because of its promising benefits. It has been widely used in cloud computing, data centre, desktop computing, and cyber physical system[1][2]etc. It allows multiple commodity operating systems instances or virtual machines (VMs) to run on a single physical machine. In simple word it means splitting up a single physical computer into several virtual computers. Virtual machine monitor (VMM), hypervisor in short is a piece of computer software that manages the hardware resource for VMs[3]. The hypervisor abstracts the hardware resources including CPU, memory, and I/O devices and then allocates them as virtual CPU, virtual memory, and virtual I/O devices to the VMs. These resources…show more content…
The method estimated the memory needs of VMs by building an MRC(Miss Ratio Curve). MRC is a curve between page misses and memoryallocation and used to identify for a particular value of physical memoryallocation. Drawing MRC requires historical traces of memory access, so itdoesn't seem to be a dynamic approach, but MEB uses this dynamically. Theytrap the memory accesses in every sampling window of time, and use that sampleto modify the previously drawn MRC and changes the allocation accordingly. Protection fault mechanism is used fortrapping the memory accesses they use, which is ahigh overhead task. Although this approach provides a reasonably accurate prediction, it causses considerable performance penalty due tothe costly memory…show more content…
The hypervisor collects idle memory fromdifferent VMs and managesitas one or morephysical memory pools. A guest OS can indirectly access this memory with a well-defined API which imposes a carefully crafted set of rules and restrictions. From the perspective of a guest OS, A memory pool appears to be fast RAMdisk withondeterministic varying size. A guest OSmay used memorypool as an extension to its memory, thusreducedisk I/O and improve performance. However, the management of memory pools is very complicated. Xen Platform[13] provide Dynamic Memory Control, which can change the amount ofhost physical memory assigned to any running virtual machinewithout rebooting it, but it fails to make a flexible response to avirtual machine which has a serious complicated tasks. Huazhong[14] University also presented a prediction model by analyzinghistorical data of each virtual machine to relocate its memory.All these methods are based on forecast accuracy, therefore, a wrong prediction will lead to a negative effect. Besides, ZhangWshowed lightweight virtual[9] machine memory management architecture for virtual computingwhich provided method by using tax rate to relocate memoryof different virtual machines.It alsocontain self and global adjusment policies to adjust the memeories but it requires a complex calculation, which may cause additional

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