Recently, cloud computing has attracted considerable attention. Cloud computing is becoming one of the most important computing and service paradigm. Cloud computing employs a group of interconnected computers which are dynamically provisioned and serve as one or more unified computing resources. Customers are able to access applications and data from a cloud at any place and at any time. Cloud computing appears to be a single point of access for all the computing needs of users.
Cloud computing technology has already developed much and is continuously proceeding on the path of development. Cloud service providers are actively seeking to develop more robust cloud computing platforms for consumers and enterprises to facilitate the on demand access regardless of time and location. Some of the available cloud based technologies are providing virtualized computing environments which host different kinds of Linux based services. Another example is which provides a centralized storage for applications and data, so users could access all the information through a web based live desktop.
Internet Data Center (IDC) is a common form to host cloud computing. An IDC usually deploys hundreds or thousands of blade servers, densely packed to maximize the space utilization. Running services in consolidated servers in IDCs provides customers an alternative to running their software or operating their computer services in house. The major benefits of IDCs include the usage of economies of scale to amortize the cost of ownership and the cost of system maintenance over a large number of machines.
With the rapid growth of IDCs in both quantity and scale, the energy consumed by IDCs, directly related to the number of hosted servers and their workload, has enormously increased over the past ten years. The annual worldwide capital expenditure on enterprise power consumption has exceeded billions of dollars, and sometimes has even surpassed spending on new server hardware. The rated power consumptions of servers have increased by ten times over the past ten years. The power consumption of data centers has huge impacts on environments. The surging demand has called for the urgent need of designing and deployment of energy efficient Internet data centers.
Information scientists are constantly trying to find better solutions to reduce power consumption by data centers. Many efforts have been made to improve the energy efficiency of IDCs including network power management, Chip Multiprocessing (CMP) energy efficiency, IDC power capping, storage power management solutions, etc. Among all these approaches, Virtual Machine (VM) technology has emerged as a focus of research and deployment. Virtual Machine (VM) technology (such as Xen, VMWare, Microsoft Virtual Servers, and the new Microsoft Hyper-V technology etc.), enables multiple OS environments to coexist on the same physical computer, in strong isolation from each other. VMs share the conventional hardware in a secure manner with excellent resource management capacity, while each VM is hosting its own operating system and applications. Hence, VM platform facilitates server-consolidation and co-located hosting facilities.
Virtual machine migration, which is used to transfer a VM across physical computers, has served as a main approach to achieve better energy efficiency of IDCs. This is because in doing so, server consolidation via VM migrations allows more computers to be turned off. Generally, there are two varieties regular migration and live migration. The former moves a VM from one host to another by pausing the originally used server, copying its memory contents, and then resuming it on the destination. The latter performs the same logical functionality but without the need to pause the server domain for the transition. In general when performing live migrations the domain continues its usual activities and from the user’s perspective—the migration is imperceptible. Using VM and VM migration technology helps to efficiently manage workload consolidation, and therefore improves the total IDC power efficiency.
For cloud computing platforms, both power consumption and application performance are important concerns. The Green Cloud architecture is utilized by cloud computing industry as an effective method to reduce server power consumption while achieving required performance using VM technologies. Reliability, flexibility, and the ease of management are the essential features of Virtual Machine (VM) technology. Due to these features Virtual Machine (VM) technology has been widely applied in data center environments. Green Cloud is an IDC architecture which aims to reduce data center power consumption, while at the same time guarantee the performance from users’ perspective, leveraging live virtual machine migration technology.
A Green Cloud automatically makes the scheduling decision on dynamically migrating/consolidating VMs among physical servers to meet the workload requirements meanwhile saving energy, especially for performance-sensitive (such as response time-sensitive) applications. Green Cloud architecture guarantees the real-time performance requirement as well as saves the total energy consumption of the IDC. In the design of Green Cloud architecture, several key issues including when to trigger VM migration, and how to select alternative physical machines to achieve optimal VM placement are taken into consideration. Green Cloud intelligently schedules the workload migration to reduce unnecessary power consumption in the IDC. Green Cloud balances performance and power in such a way that users hardly notice that their server workloads are being or have been migrated.
The above discussed technology reduces hazardous impact on our planet, keeps our environment green, and at the same time saves a lot of capital expenditure for a company that provides cloud computing service to various businesses. These benefits are ultimately passed to customers availing cloud computing services.