VRIJE UNIVERSITEIT BRUSSEL

Transcription

1 VRIJE UNIVERSITEIT BRUSSEL Faculty of Engineering Sciences - Applied Computer Science Operating Systems and Security Making Operating Systems Virtual: Mac OS X approaches Simone Ercoli Academic Year

2 Abstract In a Windows world, Mac Os is coming out very quickly. What could you do if you need something which Mac OS can t do? Don t worry, Apple s switch from PowerPC to Intel processors has made life easier and paved the way for creation of multiple virtualization software solutions. This paper aims to introduce the reader to the concept of virtualization and evaluate, test and compare different commercial and open source software solutions to obtain operating systems virtualization on MacOSX i

3 Contents Abstract i 1 Introduction 1 2 Virtualization History Virtualization types Emulation Full Virtualization ParaVirtualization Os-level Virtualization Application Virtualization Commercial Virtualization Software Parallels Desktop Description and Features VMware Fusion Description and Features Open Source Virtualization Software Virtual Box Description and Features Qemu Description and Features Performance Analysis Benchmarks Super PI IOZone Results on time measurement Time measurement problems Results on Cpu testings Results on Disk testings Conclusion 24 ii

4 List of Figures 1 Virtualization Concept Emulation Full Virtualization ParaVirtualization OS-level Virtualization OS-level Virtualization Wizard Parallesl Desktop Integration in Parallels Desktop "Like Pc" mode "Coherence" mode Connect mode Settings Parallels Settings Parallels Settings Parallels Parallels OS List Wizard VMware Fusion Settings VMware Fusion General view VMware OS List Wizard Virtual Box Memory step Settings Virtual Box Virtual Box OS List Wizard Qemu Settings Qemu Results Time Results Time Average Results Cpu on Windows XP Results Cpu on Ubuntu Write Test on Windows XP Write Test on Linux Ubuntu Read Test on Windows XP Read Test on Linux Ubuntu iii

5 1 Introduction Until few years ago the operating systems marketplace was dominated by Microsoft with Windows products in its various versions. However in recent years is coming out a strong competitor: Apple Inc. Apple products have seen their popularity grow year after year. Consequence of this growth was that many users have chosen to use apple products, which have become a reference point. Switching from Windows to Mac is not so simple for everyone because there is a basic incompatibility between windows and mac software and sometimes it is impossibile to find a mac product with the same functionality of a Windows product. Thus, one reason to choose virtualization is the necessity to use products not compatible with your current Os. Other important reasons to Virtualize, that can not to be overlooked, are: security : when you browse on internet, you want any viruses would be taken from the virtual operating system and not the real one safe-testing : try new programs that could be dangerous knowledge : learn new operating systems different from our The technique of virtualization, that seems ideal, actually had some disadvantages. It was expensive and emulate the second Os was very heavy for the system. Luckily these disadvantages have become outdated from some years thanks to new generations of computers. Figure 1: Virtualization Concept 1

6 2 Virtualization Virtualization is a software technique widely experienced that is rapidly transforming the IT landscape and changing the way people are using computing resources. Virtualization goes beyond the confines of the computers originally designed to run a single operating system and a single application. It allows you to run multiple operating systems and applications simultaneously on the same computer, thus increasing hardware utilization and flexibility. The operating system that runs the virtual machine is called the host while the virtual machine is called guest. The virtual machine code is executed directly from the host system, but the guest system thinks to be performed on a real machine with no emulation or hardware virtualization. So a virtual machine is not a physical computer, but it offers virtual hardware. Sometimes during the I/O (write to disk, file system access) you can get different performance from those that would be obtained on a real computer: performance may be better (access to the file system) or less. One of the advantages provided by the virtual machine is safety: a virtual machine is completely isolated and independent;an unexpected crash of a machine does not causes crash of other machines and does not cause crash of the host system. Therefore it is not necessary to restart the computer but only end the virtual machine and start it again. In addition a virtual machine is extremely useful for testing programs to avoid damage for the file system in case of error. 2.1 History The concept of virtualization was born in the IBM laboratories in 1960s. The basic idea was to abstract the physical characteristics of a system, and replace them with some fictitious. In this way it was possible to install a guest operating system inside another operating system, which would provide interfaces for each virtualized function like CPU, memory, I/O. 2

7 2.2 Virtualization types Currently there are five main types of virtualization: Emulation Full Virtualization ParaVirtualization Os-level Virtualization Application Virtualization Emulation In this type of virtualization, the guest operating system requires an hardware architecture that is emulated by the virtual environment. A common case is with mobile phones; application developers will use an emulated environment to test applications designed for smart phones or PDAs, for example. However this approach has poor performance and an high resource usage. Figure 2: Emulation 3

8 2.2.2 Full Virtualization In full virtualization all virtualized guests run on the same hardware architecture and the image of the guest OS is complete and unmodified. All of the guests support the same hardware and are able to execute many instructions directly on the hardware. Thereby there is an increment of performances. With this method is possible to run multiple Os from multiple vendors and virtualized images are a complete installation of the system. At the end an image file can be very very large. Figure 3: Full Virtualization ParaVirtualization Paravirtualization is a technique in which the virtualized operating system is able to communicate directly with the hypervisor (Virtual Machine Manager). To do this, is necessary a little kernel modification in the guest OS. This is a problem in case of products like Windows that does not allow editing the code for licensing reasons.the benefit of paravirtualization is the greater speed of execution of user applications. Figure 4: ParaVirtualization 4

9 2.2.4 Os-level Virtualization This kind of virtualization is without virtual machine; the single OS provides to it. There is a sharing of common features and drivers between host and guests. Each guest has its file system,configuration, IP, etc.. and can run different applications. Figure 5: OS-level Virtualization Application Virtualization In application virtualization there is a layer that intercepts all calls that are made by the virtualized application to the underlying systems. This layer redirects the calls to a virtual location. A caracteristic of this kind of virtualization is that the applications are completely abstract and interacts only with the virtualization layer. This allows applications to run on systems for which were not designed. Figure 6: OS-level Virtualization 5

10 3 Commercial Virtualization Software There are various types of commercial software that allow Mac user to virtualize an operating system; we will analyze the two main applications available (both belonging to the category of full virtualization 2.2.2) Parallels Desktop VMware Fusion 3.1 Parallels Desktop Parallels Desktop for Mac is one of the solutions tested. It is one of the most reliable and most awarded software created to run Windows applications on Mac Description and Features With Parallels Desktop for Mac, you can seamlessly run Operating Systems alongside Mac OS X with the highest levels of speed, control and security. The application has a very intuitive interface to install the "guest" system inside Parallels. The program provides us with a convenient wizard with several options (Figure 7). Figure 7: Wizard Parallesl Desktop 6

11 There are two highlighted options: one to install Windows and one to migrate an existing system in a new virtual machine through an USB cable, network, or by connecting an external drive. Obviously we can choose from a long list of operating systems (Windows and Linux mainly) of which we have a disk or installation image. It also appear the options to download, directly through the wizard, pre-configured virtual machines of Ubuntu Linux and Fedora. Then there is the possibility to import a pre-existing virtual machine, and finally the ability to install OS X Lion from the recovery partition. This is an option that can be very useful for developers and / or beta testers. For each virtual machine created it is possible to configured some parameters, such as the number of processors to allocate, the size of the virtual disk, the type of network connection, and so on. Interesting features of Parallel Desktop mainly concern the integration (Figure 8). Figure 8: Integration in Parallels Desktop It is possible to use two views: with the view "Like Pc" desktop (figure 9) System applications will be grouped in a window and will be possible to cut and paste text between Mac and the virtualized System; with the view "Coherence" (figure 10) System applications will be viewed without desktop like normal Mac s applications. Documents,musics and images will be available in Mac and in the virtualized System. 7

12 Figure 9: "Like Pc" mode Figure 10: "Coherence" mode 8

13 The start and stop virtual machines occur in fast time, allowing very good use. Sharing files between systems is effective. Mac applications can access files on Windows and vice versa without any apparent problem and also the copy of the file is done very quickly. The functions SmartConnect and SmartMount make it even easier access to the files. With SmartConnec, every time you connect a USB device to your Mac it is proposed where to mount and, eventually, the ability to store the selection for future use (Figure 11 ).With SmartMount you can mount disks instead of operating systems on your Mac (and vice versa) for quick access to files. Figure 11: Connect mode Once a system has been installed, we have a window to set all the parameters of our interest (Figures 12,13,14). Figure 12: Settings Parallels 1 9

14 Figure 13: Settings Parallels 2 Figure 14: Settings Parallels 3 To choose which Os to use, users have a nice and essential interface which provides the list of Operating Systems installed (Figure 15). Figure 15: Parallels OS List 10

15 3.2 VMware Fusion VMware Fusion for Mac is very similar to Parallels, though it doesn t offer the same functionality Description and Features To start VMware presents an initial interface to install a new "guest" system that is very basic and not convenient like Parellels ones (Figure 16). It is a 3-step prodecure without all the options provided by Parallels. Figure 16: Wizard VMware Fusion However it is possible, in addition to installing a new system through an.iso image or installation disk or to migrate an existing system in a new virtual machine. Instead it is not possible to download directly through the wizard some pre-configured virtual machines. The "Coherence" integration of VMware is very similar to integration of Parallels but in this case is called Unity and it is less integrated with the system than the integration of Parallels. 11

16 VMware doesn t present to you a pretty window when you connect an usb drive and there is not the possibility to choose where to mount the drive and the possibility to store the selection. Instead you have a good functional window to set the parameters of the guest operating systems (Figure 17). Figure 17: Settings VMware Fusion General view Like in Parallels, users have an interface which provides the list of Operating Systems installed (Figure 18). Figure 18: VMware OS List 12

17 4 Open Source Virtualization Software In addition to commercial products mentioned above, we can provide a good operating system virtualization using open source products. In this context we will analyze two important open source software : Virtual Box Qemu 4.1 Virtual Box VirtualBox is a powerful x86 virtualization product. This is a software extremely feature rich and it has high performance for less experienced users, but it is also an excellent solution for professional users who want to use a free open source virtualization software released under the GNU General Public License (GPL) Description and Features VirtualBox runs on all major platforms (Windows, Linux and Macintosh) and it is able to virtualize system like Windows, DOS / Windows 3.x, Linux, and OpenBSD. The great virtue of this application is to be found in the open source project and in the rich community that contributes to the development of the project every day for an increasingly significant enrichment of the product s stability. Figure 19: Wizard Virtual Box 13

18 Create a new virtual machine is very easy with Virtual Box. Just click on the "New" button at the top of the VirtualBox Manager window and a wizard will guide the user through all necessary steps like select the operating system type and select the memory (RAM) that VirtualBox should allocate every time the virtual machine is started (Figure 20). Figure 20: Memory step When a VM gets started for the first time, another wizard, the First Start Wizard, will pop up to help you select an installation medium. It is possible to select a medium to install an operating system from physical CD or DVD media or from an.iso file image. 14

19 Regarding the setting of parameters, we can use a nice interface that is at level of the commercial ones (Figure 21). Figure 21: Settings Virtual Box To manage Os, users can use a nice interface that provides a list of the Operating Systems with relative settings (Figure 22). Figure 22: Virtual Box OS List 15

20 4.2 Qemu Qemu is the second open source software for virtualization which will be discussed in this paper. Like other products, allows the installation of various operating systems on one machine, which can be launched like any other system software. In particular, for this project has been used Q [kju:] emulator, a feature packed Cocoa port of QEMU Description and Features Q emulator can run Windows, Linux and other systems on Mac. It presents a simple and minimalist interface whereby create and manage guest systems ( our operating systems ). Figure 23: Wizard Qemu 16

21 Qemu setting interface is not as beautiful as that of virtualbox, but it is functional and presents all necessary options to set the guest system. Figure 24: Settings Qemu 17

22 5 Performance Analysis To analyze our software we used two basic approaches. The first approach is a simple "time measurement" during the installation of Windows 1 and Linux 2 for each virtual machine, while the second approach is a "performance measurement" using two benchmark software. 5.1 Benchmarks The choice of programs used to analyze our software was performed looking for benchmarks available for both operating systems. Benchmarks are conceptually divided in two parts: the first part concerns the analysis of CPU performance by calculating of PI (π) with Super PI software for Windows and a combination of "shell" commands time and pi for Linux the second part concerns the analysis of the ability to write/read on disk using IOZone software For our tests we used the 1.5-mod version of Super PI and 3.0 version of IOZone Super PI Super PI is one of the most popular freeware software used to benchmark the CPU, and in general to test the RAM 3. Super PI runs an algorithm (Gauss-Legendre) through which it calculates the value of π, with a variable number of decimal places to the maximum value of 32 million IOZone IOZone is a really well done cross-platform freeware software that can analyze in detail all types of hard disk operation. It is dedicated to testing performance of file systems from the point of view of the I/O 4. This tool is also able to highlight, with 3 dimensional graphs, the relationship between the file system s responce with other factors like the processor cache. 1 Windows XP Service Pack 3 2 Linux Ubuntu 11 3 Random Access Memory 4 Input/Output operations 18

23 5.2 Results on time measurement Regarding time measurement on the installation of the various operating systems with the different software, we obtained clear results that show us how,in this phase, the commercial products have an higher execution speed than the open source products Figure 25: Results Time Figure 26: Results Time Average 19

24 5.2.1 Time measurement problems The problems we found are only with Q software. During this test phase we obtained very bad results testing Qemu, more than 6 hours for installing Windows XP and more than 4 to installing Ubuntu. After this observation, we decided to "eliminate" Q software from the other testing due to its inability to compete with the other software. 5.3 Results on Cpu testings For this test we calculated 1 million digits of pi with the same configuration for all our machines. The results are the time needed to perform the corresponding operations and less time means best performance. It is important to remember that we used two different methodologies to calculate pi on Windows XP and Ubuntu, so the results between the two operating systems are not comparable. Figure 27: Results Cpu on Windows XP 20

25 Figure 28: Results Cpu on Ubuntu 5.4 Results on Disk testings As written previously (5.1.2), IOzone allows to analyze the performance of a disc in detail. In particular it is possible to know the execution speed of each disk operation. Among all we decided to show performance in reading and writing. Although they are only a fraction of the total operations that you can do, they are the most common. We tested readings and writings to disk with a file size of 512MB with a record size of 4KB. 21

26 Figure 29: Write Test on Windows XP Figure 30: Write Test on Linux Ubuntu 22

27 Figure 31: Read Test on Windows XP Figure 32: Read Test on Linux Ubuntu 23

28 Regarding test results of the operation "write" disk, we can see an overwhelming superiority of Windows XP on Ubuntu. This fact is certainly attributable to an increased "ability" of the NTFS file system (the system used by Microsoft) to write 512MB files with records of 4K. We can also see how Windows Parallels and Ubuntu Parallels are very powerful and how Windows VMware and Linux Virtual Box are less powerful than the other two. Regarding test results of the operation "read" disk we have very surprising results. We can see that now Windows Parallels and Linux Parallels are less powerful than other two and like Windows Virtual box and Linux VMware are the best. We want to remember that the differences between operating systems Windows and Linux are also due to the predisposition of the filesystem to write files of the size chosen by us for testing. This fact does not mean that an operating system is faster than another in all situations, but only in the particular situation of test. 6 Conclusion Putting together test results, and analyzing them in a broader perspective, we can say that for commercial uses or uses that need of safety in general, commercial products are the best choice. In this case Parallels Desktop seems to be the best commercial software at present and exceeds vmware in features and usability. However vmware seems a good choice for Linux virtualization. For a virtualization that is not correlated with a commercial purpose, we find very not convenient to turn attention at commercial software, but very interesting to explore freeware products like Virtual Box. Although Virtualbox is a free software, it can rely on a big group of developers that are manteining it up with times and users needs. From our tests comes out also the big competitiveness of Virtual Box compared the other commercial products. At the end we can say that Parallels Desktop is the top software, VMware is falling behind and Virtual Box is the free alternative most functional and performant that we would like to advise. 24