目前，虛擬化技術越來越流行在許多的資料中心。傳統資料中心是由許多臺伺服器串聯組成，這樣的方式會造成機房空間的浪費並且難以管理每一台電腦造成一些硬體上面的浪費。所以目前許多公司會使用虛擬化技術來管理資料中心。透過虛擬化技術可以虛擬多台虛擬機器，並且每一台虛擬機器都是獨立的，不會互相干擾。虛擬化技術利用虛擬化監管程式來管理這些虛擬機器，可以動態分配硬體效能給這些虛擬機器使用，例如: CPU、memory等，但是在I/O方面卻成為虛擬化技術的瓶頸，當部份虛擬機器需要更大的I/O效能時，只能透過更換效能更好的儲存裝置來達到I/O的提升且常較大I/O效能的儲存裝置成本較高，所以我們提出了虛擬機器底下的多層次儲存裝置的搬移模組，讓我們可以動態分配儲存裝置給虛擬機器使用，可以達到整體I/O效能的提升。

Nowadays, virtualization technologies have become very popular in many data centers. It is difficult to manage a lot of physical servers in a traditional data center and uneven resource utilization of the physical servers could be a problem. Therefore, virtualization technologies have been used to simplify the management of the physical servers and enhance the resource utilization. In particular, a Hypervisor is a software layer which manages the hardware resource like CPU, main memory, and storage space. When the I/O throughput need more performance, the system will change the faster storage. A multitier storage system that consists of different levels of storage devices can be used to improve I/O performance. In the thesis, we will propose a migration component in a hypervisor with a multitier storage system. With the migration component, we can migrate appropriate virtual machines’ data among different levels of storage devices.

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