A New Scalable Server Construction Method Based On. Virtual Machine Transfer and Duplication

Transcription

1 A New Scalable Server Construction Method Based On Virtual Machine Transfer and Duplication Yuko KAMIYA and Toshihiko SHIMOKAWA Graduate School of Information Science, Kyushu Sangyo University, JAPAN Faculty of Information Science, Kyushu Sangyo University, JAPAN ABSTRACT In the Internet world, server systems play a crucial role in continuously supporting the 24/7 operation of the network. However, some problem issues have been identified with the current server systems on the Internet. In this research, we tackle two of these problems, i.e., the processing power and network bandwidths, and proposed solutions on these issues. In this research, we use virtual machines to solve the above-mentioned problems. Generally, a virtual machine consists of some files which are easy to duplicate and transfer. By duplicating a virtual machine at a server and transferring it to a high-performance processing server, we can increase the origin server s processing power. Likewise, by tapping the wide bandwidth of a high-performance processing server, we can increase the network bandwidth. We call this idea, Server Proliferation. We designed the Virtual Machine Control Protocol (CP) to implement Server Proliferation. CP has six basic functions; namely, to authenticate users, to obtain information of remote physical machines, to obtain information of remote networks, to transfer virtual machines, to control remote virtual machines, and to provide help functions. We implemented a prototype system of CP, called PIYO (ProlIferate and Yield Objects). PIYO is a server-client system. At the server side, PIYO processes CP and controls the virtual machines. At the client side, PIYO processes CP and duplicates the virtual machines. Lastly, we evaluated Server Proliferation by using PIYO. Keywords: Virtual Machine, Server Mobility, Server Proliferation 1. INTRODUCTION With the rapid developments and widespread use of information systems and ubiquitous environments, the Internet becomes one of the base infrastructures in realizing these systems. The Internet server systems provides many services and some of these servers are frequently accessed by many users. We can say that server system is one of the key technologies energizing the Internet. However, some problem issues have been identified with the current server systems. In this research, we tackle two of the problems and proposed solutions. The first problem is the processing power, i.e., if the processing power of a server is insufficient, it may not be able to continue to provide its service. The second problem is the network bandwidth, i.e., if the network bandwidth is narrow and many requests are flooding the server, the network may suffer congestion. A possible solution to the first problem is to increase the number of servers and/or by using high performance machines. However, usually the peak load time does not last long. Therefore, using high performance machines and/or increasing the number of machines are costly alternatives. Likewise, it needs time to increase the number of machines. Therefore, it is difficult to provide an adaptive solution to the rapid increase of users access. The second problem can be solved by distributing machines in a wide area. This is because accesses from clients are distributed among servers. However, it is difficult to distribute physical machines dynamically. In this research, we use virtual machines to solve the above-mentioned problems. 2. VIRTUAL MACHINE TECHNIQUE Virtualization is one of the key techniques oftentimes used in computer science. For example, the virtual memory technique virtualizes a memory to get large memory spaces. On the other hand, the virtual machine technique virtualizes a whole machine. There are two kinds of virtual machine models. The first one is Host OS model. In this model, the usual OS, i.e., Windows, Linux and so on, runs on a physical machine. A virtual machine runs as one of the applications on the host OS. The other one is the Virtual Machine Monitor model. In this model, a special purpose OS,

2 called virtual machine monitor, runs on a physical machine. Virtual machine monitor only supports to run virtual machines. 3. SERVER PROLIFERATION support at layer 4, and requires modifying the applications. However, it has an advantage on the performance. So, we use both Mobile IP and SCTP. In this research, our goal is to increase the server processing power and network bandwidth, dynamically. To realize this, we propose a new idea, called Server Proliferation. The basic idea of Server Proliferation is simple. We build all services on top of virtual machines. We duplicate and/or transfer a virtual machine when needed. By duplicating a virtual machine and transferring it to a high-performance processing server, we can increase the origin server s processing power. Likewise, by tapping the wide bandwidth of a high-performance processing server, we can increase the network bandwidths. In order to avoid network congestion, we can distribute duplicated virtual machines in a wide area. Generally speaking, a virtual machine consists of a hardware configuration information file and some hard disk image files, which are easy to duplicate and transfer. One case of using Server Proliferation is as follows. Server providers can build their own servers on virtual machines and not directly on physical machines. By this, they can easily increase and transfer their servers. To run these servers, they can distribute the physical machines all over the Internet with virtual machine monitors. To run many virtual machines on these virtual machine monitors, they have to use high performance machines. As we mentioned earlier, high performance machines are very expensive. However, since these machines can serve many servers, the cost can be offset by its services. At the early stage, a server provider can run its virtual machine on a virtual machine monitor. When its service becomes popular, it has two choices, i.e., either to transfer the virtual machine or process duplication. When the server provider transfers its virtual machine to another virtual machine monitor that runs on a high-performance machine, it can increase its processing power. Figure 1 shows a virtual machine transfer. However, if a virtual machine is transferred to another network, the IP address must be changed. Therefore, users cannot continue their communication between servers. To solve this problem, we use Mobile IP[1] and/or SCTP[2][3]. Mobile IP adds mobility support to IP, and is used for client mobility. However, in our case, we use it for server mobility. Mobile IP provides mobility support at layer 3. Therefore, we don t have to modify applications. However, it has a disadvantage on the performance. On the other hand, SCTP provides mobility Internet Figure 1. Transferring a Virtual Machine When a server provider duplicates its virtual machine, it can increase its processing power and network bandwidths. Figure 2 shows multiple duplications of a virtual machine. By increasing the network bandwidths, it can prevent network congestion. Also, by navigating users to the suitable server, it can distribute the load of the server provider. Internet Figure 2. Duplications of a Virtual Machine Furthermore, aside from increasing the server processing power and increasing the bandwidth, Server Proliferation can be used to solve some environmental problems. We can save energy by transferring virtual machines from daytime area to nighttime area. This is because the temperature is different between daytime and nighttime, i.e., nighttime is cooler than daytime. It needs more energy to cool server systems at daytime rather than at nighttime. If the processing of virtual machines can be transferred to a nighttime area, then we can reduce the energy consumption, and thus contribute a solution to some environmental problems.

3 Command Function AUTH Get authentication from a server GETHOST Get information of a server GETNET Get information of a remote network SEND Send virtual machine to a server RECV Receive a virtual machine from a server START Start a virtual machine on a server STOP Stop a virtual machine on a server PAUSE Pause a virtual machine on a server UNPAUSE Unpause a virtual machine on a server DESTORY Shutdown a virtual machine on a server REBOOT Reboot a virtual machine on a server Terminate connection between a client QUIT and a server LIST List virtual machines on a server Table 1. CP commands 4. CP: VIRTUAL MACHINE CONTROL PROTOCOL We can transfer virtual machines from one physical machine to another, and execute the virtual machine on the other physical machine. To implement this, we designed a new protocol, called CP: Virtual Machine Control Protocol. CP is a simple ASCII-based protocol like the other major protocols on the Internet. It uses reliable ordered stream transport protocol. Basically, it uses TCP. CP has six functions and they are described as follows. 1) To authenticate users This function is to authenticate a CP client by the CP server. 2) To get information of a remote physical machine This function is to get information about a remote physical machine; i.e., CPU specs, memory size, HDD size, network bandwidths, and so on. With this information, CP clients can judge whether to send or not a virtual machine to a certain physical machine. 3) To get information of a remote network This function is to get information of remote networks; i.e., IP address, default gateway, nameserver, netmask, and so on. CP clients can use this information to modify a virtual machine before sending it. 4) To transfer virtual machines This function is to transfer a virtual machine from a CP server machine to a CP client machine, and vice versa. 5) To control a remote virtual machine This function is to control a remote virtual machine. It can start, suspend, and stop remote virtual machines. 6) To provide help functions This function is to provide help functions. For example, it can list up remote virtual machines, or connect a CP server machine to a CP client machine. Table 1 shows the lists of CP commands with brief descriptions of each. 5. PROTOTYPE IMPLEMENTATION OF CP We implemented a prototype system of CP, called PIYO: ProlIferate and Yield Objects. PIYO is a server-client system. At the server side, PIYO processes CP and controls the virtual machines via the virtual machine monitor. Current implementation uses Xen[4] as the virtual machine monitor. Xen is an open-source para-virtualizing virtual machine monitor for the x86 processor architecture. Xen can execute multiple virtual machines on a single physical system with close-to-native performance. At the client side, PIYO processes CP and duplicates virtual machines. PIYO processes the virtual machine duplication as follows. It copies the image files of a virtual machine, and gets information about a remote network; such as its IP address, netmask, default router, and so on, from a PIYO server. It then creates a new MAC address. PIYO applies this information to the copied virtual machine to be able to run on a remote network. PIYO is written in Ruby. 6. EXPERIMENTS We conducted three experiments to evaluate PIYO. In the first experiment, we measured the time to duplicate a virtual machine. As mentioned in Section 5, PIYO duplicates a virtual machine in two steps, and we measured the time for each step. Also, as we said in Section 1, a virtual machine consists of a hardware configuration information file and some hard disk image files. We call these files as virtual machine construction files. We measured the time to copy a virtual machine for five times according to the following procedures. 1) We copied the virtual machine construction files by the PIYO client. We measured the time incurred, and call it Copy time. 2) We modified the copied virtual machine construction files.

4 To do so, we applied new information i.e., MAC address to the hardware configuration information file. Likewise, we applied new information i.e., IP address, default gateway, nameserver and netmask to the OS configuration files in the copied hard disk image files. To modify these files in the hard disk image files, we mounted those hard disk image files via the loop back device of Linux. We measured the time incurred, and call it Modify time. the QGPOP network at KSU campus. And the third machine, called zyx.qgpop.net, is located on the QGPOP network in Kyushu University. Table 4 shows the physical machine specs of these three machines. Table 2 shows the physical machine specs in this experiment, while Table 3 shows the results. CPU Pentium4 2.40GHz Memory 1.2GB HDD UDMA100 40GB Table 2. The machine specs (First expt.) Figure 5. The experimental environment (Second expt.) Copy time Modify time Total First 237 seconds 1 second 238 seconds Second 189 seconds 6 seconds 195 seconds Third 210 seconds 3 seconds 213 seconds Forth 208 seconds 4 seconds 212 seconds Fifth 233 seconds 4 seconds 237 seconds Average seconds 3.6 seconds seconds Table 3. The time to duplicate a virtual machine This result shows that on the average, it took seconds to copy and modify a virtual machine. Most of the time was spent in copying the virtual machine construction files. This indicates that by reducing the virtual machine copy time, we can reduce the virtual machine duplication time. In the second experiment, we measured the virtual machine transfer time. Figure 5 shows the experimental environment. There are two separate networks used in this experiment; namely, the Kyushu Sangyo University (KSU) Campus Network, or KIND, and the Kyushu Gigapop Project Network, or QGPOP. QGPOP network is a research network connecting some universities and companies in Kyushu. At KSU, we can use both the KIND and QGPOP networks. These two networks are connected by the Internet. We use three physical machines in this experiment. The first machine, called cute.nw.is.kyusan-u.ac.jp, is located on the KIND network. The second machine, called ah.qgpop.net, is located on hostname CPU Memory Network cute Pentium4 2.4GHz 1.2GB 1Gbps ah Xeon 2.4GHz 512MB 1Gbps zyx Xeon 2.4GHz 512MB 1Gbps Table 4. The machine specs (Second expt.) Here, we measured the transfer time in two different scenarios. In the first scenario, we transferred a virtual machine between hosts ah and zyx. Both machines are connected to the QGPOP network, but ah is located at KSU while zyx is located in Kyushu University. In the second scenario, we transferred a virtual machine between hosts cute and ah. These machines are located both at KSU. But cute is connected to the KIND network and ah is connected to the QGPOP network. The size of the virtual machine is 2GB. Table 5 and Table 6 are the results of the experiments. Transferring time First 59 seconds Second 57 seconds Third 59 seconds Forth 58 seconds Fifth 57 seconds Average 58 seconds Table 5. The transfer time between ah and zyx

5 Transferring Time First 1 hour 8 minutes 18 seconds Second 1 hour 13 minutes 55 seconds Third 1 hour 14 minutes 37 seconds Forth 1 hour 15 minutes 40 seconds Fifth 1 hour 16 minutes 30 seconds Average 1 hour 13 minutes 48 seconds Table 6. The transfer time between ah and cute SCP FTP PIYO First 136 seconds 56 seconds 59 seconds Second 140 seconds 54 seconds 58 seconds Third 146 seconds 56 seconds 60 seconds Forth 131 seconds 62 seconds 61 seconds Fifth 132 seconds 56 seconds 60 seconds Average seconds 56.8 seconds 59.6 seconds Table 8. The results in the final experiment These results show that the average transfer time between QGPOP nodes is 58 seconds. This is because the network distance between the two physical machines is short. On the other hand, the average transfer time between nodes in QGPOP and KIND is 1 hour 13 minutes 48 seconds. This is because the network distance between the two physical machines is long. This too long time to transfer a virtual machine in a wide area is a big problem. Therefore, we must improve the virtual machine transfer time. In the final experiment, we compare the transfer time of a virtual machine using other known tools. We understand that it takes too long time to transfer a virtual machine in a wide area, and so we compared PIYO with existing tools: SCTP and FTP. Figure 6 shows the experimental environment and Table 7 shows the specs of the physical machines. We use the same specs for the machines used in this experiment. Table 8 shows the results of this experiment. The result shows that PIYO can transfer virtual machines faster than SCTP, while PIYO can transfer as fast as FTP. These results justifies that PIYO can withstand the comparison with existing tools. 7. RELATED WORKS Some related works include the Live Migration[5] of Xen and the otion[6] of ware which are also virtual machine transferring techniques. These techniques though can only transfer virtual machines between local area networks. However, our method can transfer virtual machines between wide area networks. Quasar[7] is a mobile computing system built on top of CPU Emulator QEMU. Quasar provides support for migration of QEMU s virtual machine. Quasar only provides server migration. However, our research supports both server migration and server proliferation. 8. CONCLUSIONS Figure 6. The experimental environment (Final expt.) CPU Pentium4 2.40GHz Memory 256MB HDD UDMA100 40GB Table 7. The specs of the physical machines (Final expt.) In this research, we proposed a new method to construct servers, called Server Proliferation. We designed and implemented a prototype of a new protocol, called CP, to implement our method. In our method, we can increase the server processing power and network bandwidths, dynamically. Our method is based on virtual machine technique. We can increase the number of virtual machines when more processing power is needed and can transfer virtual machines to remote networks. Moreover, our method can also be used to help solve some environmental problems. The current prototype system only supports the sub-functions of CP. In the future, we will implement CP in full and evaluate it with due consideration to environmental problems. Furthermore, since the duplication and transfer time of virtual machines took too long, we plan to reduce the time and address

6 this issue more deeply. ACKNOWLEDGMENTS This research was supported in part by MEXT in Japan under Grants-in-Aid for Scientific Research on Priority Area , and by JSPS in Japan under Grants-in-Aid for Scientific Research (B) REFERENCES [1] C. Perkins, Ed., IP Mobility Support for IPv4, RFC3344, August [2] R. Stewart, Stream Control Transmission Protocol, RFC4960, September [3] R. Stewart, Q. Xie, M. Tuexen, S. Maruyama, M. Kozuka, Stream Control Transmission Protocol (SCTP) Dynamic Address Reconfiguration, RFC5061, September [4] Home of the Xen hypervisor, [5] C. Clark, K. Fraser, S. Hand, J. G. Hansen, E. Jul, C. Limpach, I.Pratt, and A. Warfield, Live Migration of Virtual Machines, In Proceedings of the 2nd ACM/USENIX Symposium on Networked Systems Design and Implementation (NSDI), May [6] ware, otion Overview, Virtual Machine Migration, Virtualization, [7] Koichi Onoue, Yoshihiro Oyama, Akinori Yonezawa, Quasar: A Mobile Computing System Based on CPU Emulator QEMU, In Proceedings of The 8th Workshop on Systems for Programming and Applications (SPA 2005), March 2005.