VCE: A New Personated Virtual Cluster Engine for Cluster Computing Mohsen Sharifi, Masoud Hassani Ehsan Mousavi Khaneghah, Seyedeh Leili Mirtaheri Computer Engineering Department Computer Engineering Department Iran University of Science and Technology Iran University of Science and Technology Tehran, Iran Tehran, Iran [email protected], [email protected] [email protected], [email protected] Abstract— Virtualization addresses the problem of making more On the other hand, there are typically three types of owners, efficient use of available computer resources. Recently, virtual who use their workstations mostly for: clusters try either to virtualize a single physical cluster into (1) Sending and receiving email and preparing multiple independent virtual clusters to provide a virtual server documents. as a highly scalable and highly available server built on a cluster (2) Software development, editing, compiling, debugging of real servers, or to share physical clusters to offer economies of scale and more effective use of resources by multiplexing. and testing. However, since programs running on a cluster demonstrate (3) Running compute-intensive applications. different types of requirements as their executions proceeds, such as support for intensive processing, security, and massive data Cluster computing tries to steal spare cycles from (1) and communications, it is therefore quite unrealistic to assume that a (2) to provide resources for (3). However, this requires statically configured cluster with a predetermined number of overcoming the ownership hurdle - people are very protective nodes with specific features and support can do any good for of their workstations. To do this usually requires organizational such programs. This paper presents a different usage for mandate that computers are to be used in this way. Stealing virtualization in the context of distributed computing using cycles outside standard work hours (e.g. overnight) is easy, but virtual clusters, called Virtual Cluster Engine (VCE), that stealing idle cycles during work hours without impacting provides a computing environment that can be both statistically interactive use (both CPU and memory) is much harder. and dynamically (re)organized according to the needs and requirements of programs, so that they can achieve the best There are more motivations for using cluster computing in possible performance as they suit themselves, indeed within the addition to the above initiative: constraints of available resources. Feasibility of the proposed The communications bandwidth between workstations architecture for VCE has been studied on an experimental is increasing as new networking technologies and platform using seven real machines, VMWare ESX, VMotion, protocols are implemented in LANs and WANs. and VMWare programming kit, and a number of virtual machines. On average, 20% improvement on response times Workstation clusters are easier to integrate into under VCE was experienced. existing networks than special parallel computers. Surveys show utilization of CPU cycles of desktop Keyword: Virtualization, Virtual Cluster, Cluster Computation, workstations is typically <10%. Distributed Computing, Operating System Performance of workstations and PCs is rapidly improving I. INTRODUCTION As performance grows, percent utilization will Generally speaking, there have been three ways to improve decrease even further distributed computing performance: Organizations are reluctant to buy large supercomputers, due to the large expense and short Work harder by using faster hardware, e.g. reducing useful life span. the time per instruction. The development tools for workstations are more Work smarter by using optimized algorithms and mature than the contrasting proprietary solutions for techniques. parallel computers - mainly due to the non-standard Get help from multiple computers to solve problems nature of many parallel systems. faster. Workstation clusters are a cheap and readily available alternative to specialized High Performance Computing (HPC) platforms. Use of clusters of workstations as a distributed provide a context for our proposition. Section 3 presents the compute resource is a very cost-effective incremental architecture of a new personated Virtual Cluster Engine for growth of system. cluster computing, called VCE. Section 4 studies the feasibility of VCE through experimentation. Section 5 concludes the Some of the key operational benefits of clustering include: paper. System High Availability (HA). Offers inherent high system availability due to the redundancy of II. RELATED WORK hardware, operating systems, and applications. Virtualization addresses the problem of making more Hardware Fault Tolerance. Redundancy for most efficient use of available computer resources. This is done by system components (e.g. disk-RAID), including both providing an abstraction layer which maps real resources to hardware and software. virtual resources. Virtualization solutions have existed for more Operating System (OS) and Application Reliability. than forty years. For example, the IBM VM/370 project from Running multiple copies of the OS and applications, the early sixties used virtualization to expose a virtual and through this redundancy System/370 machine to the user. There is a wealth of Scalability. Adding servers to the cluster or by adding virtualization technologies like: QEMU [3], BOCHS [4], more clusters to the network as the need arises or OpenVZ [5], coLinux [6], Xen [7], and a lot more. In this paper CPU to SMP. we are not going to focus on any particular technology or High Performance. Running cluster enabled programs. present any new virtualization technology, but rather intend to put forward a different usage for virtualization in the context of There are so many applications for cluster computing too, distributed computing using virtual clusters. including: The common place technologies on virtual clusters, like Numerous Scientific and Engineering Applications. COD [1], VPC [8], ZONE.NET [9], LVS [2], NLB [10,11], Parametric Simulations. SV [12], VS [13], GVC [14] and many more try either to Business Applications, like E-commerce Applications virtualize a single physical cluster into multiple independent (Amazon.com, eBay.com), Database Applications virtual clusters to provide a virtual server as a highly scalable (Oracle on cluster), and Decision Support Systems. and highly available server built on a cluster of real servers, or Internet Applications, like Web serving/searching, to share physical clusters to offer economies of scale and more Infowares (yahoo.com, AOL.com), ASPs effective use of resources by multiplexing. (Application Service Providers), eMail, eChat, VCE presents a new perspective and usage for cluster ePhone, eBook, eCommerce, eBank, eSociety, virtualization based on virtual cluster technology. Virtual eAnything, and Computing Portals. clusters were originally used for educational purposes in cases Mission Critical Applications, like Command Control where physical resources were not sufficient to run (new) systems, banks, nuclear reactor control, star-war, and systems or applications. A recurrent example is to deploy a handling life threatening situations. virtualizer, like Xen and VMWare [15], on a single computer to create a number of virtual machines interconnected by a Given this introductory background, what does a cluster virtual switch, allowing variety of experimentations on the really mean? A cluster is a type of parallel or distributed single computer as though they run on a real network. processing system, which consists of a collection of Nowadays, virtual clusters are mostly used for real interconnected stand-alone or complete computers computation. Advances in multi-processor and multi-core cooperatively working together as a single, integrated technology, increased maintenance costs of real machines, computing resource. The general focus nowadays is mostly (as scalability and flexibility of virtual machines, capability of in this paper) on MIMD model, using general purpose dynamically transferring machine state from one machine to processors or multi-computers. another, has attracted industry and academia to use virtual machines extensively in the construction of virtual clusters in Clusters have been subjected to virtualization in various support of real computations. ways, either to virtualize a single physical cluster into multiple independent virtual clusters [1], or to share physical clusters to offer economies of scale and more effective use of resources by Dinda [16] presents a case for grid computing based on the multiplexing [2]. In this paper we are not going to focus on any use of virtual machines. This was the first successful technique particular cluster virtualization technology or present a new that deployed a bank of virtual machines in support of varieties of tasks. It was however restricted in that assignment of virtual cluster virtualization technology, but rather intend to put machines to tasks were only allowed once and only upon start forward a different usage for virtualization in the context of of computation. VCE furthers this capability by allowing run- distributed computing using virtual clusters. We introduce a time cluster reorganization (i.e., reassignment of virtual completely different perspective of cluster virtualization. machines to tasks) even after the start of computation. The rest of paper is organized as follows. A number of Foster