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2. 2 VIRTUAL MACHINES By: Satya Prasanna Mallick Reg.No-17708

3. Virtualization Virtualization deals with “extending or replacing an existing interface so as to mimic the behavior of another system” Virtual system examples: virtual private network, virtual memory, virtual machine

4. 4 Virtual Machine A Virtual Machine is a software that creates a virtualized environment between the computer platform and the end user in which the end user can operate software.

5. 5 Description The operating system creates the illusion of multiple processes, each executing on its own processor with its own (virtual) memory.

6. Physical machine

7. 7 Virtualization Virtualization is an abstraction layer that decouples the physical hardware from the operating system to deliver greater IT resource utilization and flexibility. It allows multiple virtual machines, with heterogeneous operating systems to run in isolation, side-by-side on the same physical machine.

8. 8 Virtualization contd.. Each virtual machine has its own set of virtual hardware (e.g., RAM, CPU, NIC, etc.) upon which an operating system and applications are loaded. The operating system creates the illusion of multiple processes, each executing on its own processor with its own (virtual) memory.

9. Non-virtualized Data Centers Too many servers for too little work High costs and infrastructure needs –Maintenance –Networking –Floor space –Cooling –Power –Disaster Recovery

11. 11 History Virtualization was first introduced in the 1960s to allow partitioning of large, mainframe hardware. In the 1990s, researchers began to see how virtualization could solve some of the problems associated with the proliferation of less expensive hardware, including underutilization, escalating management costs and vulnerability.

12. CS502 Spring 2006 History – CP67 / CMS IBM Cambridge Scientific Center Ran on IBM 360/67 Alternative to TSS/360, which never sold very well Replicated hardware in each “process” Virtual 360/67 processor Virtual disk(s), virtual console, printer, card reader, etc. CMS: Cambridge Monitor System A single user, interactive operating system Commercialized as VM370 in mid-1970s

13. CS502 Spring 2006 VMware – Modern Virtual Machine System Founded 1998, Mendel Rosenblum et al. Research at Stanford University VMware Workstation Separates Host OS from virtualization layer Host OS may be Windows, Linux, etc. Wide variety of Guest operating systems < $200

14. 14 What is Virtual Machine Monitor? The host software that provides virtualization is often referred to as a virtual machine monitor (VMM) or hypervisor. The VMM gives each virtual machine an illusion of a complete computer to itself.

15. So, it is just like Java VM, right?

17. CS502 Spring 2006 Features The resources of the physical computer are shared to create the virtual machines – CPU scheduling can create the appearance that each user has own processor – Spooling and a file system provide virtual card readers, virtual line printers – Disk partitioned to provide virtual disks – A normal user time-sharing terminal serves as the virtual machine operator’s console

18. 18 Features Each virtual machine has its own set of virtual hardware (e.g., RAM, CPU, NIC, etc.) upon which an operating system and applications are loaded. The operating system sees a consistent, normalized set of hardware regardless of the actual physical hardware components.

21. CS502 Spring 2006 Virtual Machines (continued) Virtual-machine concept provides complete protection of system resources – Each virtual machine is isolated from all other virtual machines. – However, no direct sharing of resources Virtual-machine system is a good vehicle for operating- systems research and development. – System development is done on the virtual machine does not disrupt normal operation – Multiple concurrent developers can work at same time

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23. 23 Architecture

24. CS502 Spring 2006 VMware Architecture

25. 25 Benefits 1. Partitioning - Multiple applications and operating systems can be supported within a single physical system. - There is no overlap amongst memory as each Virtual Memory has its own memory space.

26. CS502 Spring 2006 VMware Server Free version released in 2006 http://www.vmware.com/products/server/ Runs on any x86 server hardware and OS Windows Server and Linux Host OS’s Partition a physical server into multiple virtual server machines Target market – IT centers providing multiple services Allows separate virtual servers to be separately configured for separate IT applications – Provisioning Portability, replication, etc.

28. Run legacy software on non-legacy hardware Run multiple operating systems on the same hardware Create a manageable upgrade path Manage outages (expected and unexpected) dynamically

29. Reduce costs by consolidating services onto the fewest number of physical machines http://www.vmware.com/img/serverconsolidation.jpg

30. 30 Summary Virtual machines are a number of discrete identical execution environments on a single computer, each of which runs an operating system. This can allow applications written for one OS to be executed on a machine which runs a different OS which provide a greater level of isolation between processes than is achieved when running multiple processes on the same instance of an OS.

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