Virtualization and Virtual Machines (VM) Shilpa Jain

Transcription

1 Virtualization and Virtual Machines (VM) Shilpa Jain

2 What is it? Virtualization is a framework or methodology of dividing the resources of a computer into multiple execution environments, Done by applying one or more concepts or technologies such as: hardware and software partitioning, time-sharing, emulation, quality of service, and many others. Virtualization is an abstraction layer that decouples the physical hardware from the operating system to deliver greater IT resource utilization and flexibility.

3 A Brief History Not a new concept 1960 s at IBM: M44/44X Project, the goal of which was being to evaluate the then emerging time sharing system concepts The architecture was based on virtual machines: the main machine was an IBM 7044 (M44) and each virtual machine was an experimental image of the main machine (44X) IBM and MIT headed research through the years and eventually developed the idea of a Virtual Machine Monitor (VMM)

4 Different Types of Virtual Machines Modern computer systems are composed of various hardware and software layers Virtualization inserts a software layer (VMM) at different points in this architecture, comes in three variants: hardware-level virtualization operating system-level high-level language virtual machines

5 Hardware Level Virtualization Virtualization layer sits right on top of the real hardware Since the VM presents a version the real machine, all software written for that hardware (x86) will run on that virtual machine Original design from IBM in the 1960 s More on this later

6 Operating System Level Virtualization Virtualization layer sit between the operating system and the application programs that run on the operating system Virtual Machine runs applications, or sets of applications written for the operating system but in a controlled environment use host OS API FreeBSD jails act like this. Application Virtual Machine VMM Applications OS Real Machine

7 High-level Language Virtual Machines The virtualization layer Java Byte Code sits as an application program on top of the JVM operating system Applications Can run any programs written for that virtual machine abstraction OS regardless of the operating system hosting that virtual Real Machine machine Anyone have an Java, Smalltalk example of this?

8 Attributes of All Virtual Machines Software Compatibility VM provides compatible abstraction so all software written for the machine that VM is virtualizing will run on it Java: write once, run anywhere Isolation All software running on the virtual machine is contained within it and can t affect other VM s or processes

9 Attributes of All Virtual Machines Encapsulation Virtual machines provide a level of indirection. Any software running within them can be controlled and manipulated. Java VM for example can perform run time error checking and garbage collection that C++ compiled code can t do running directly on the hardware Performance Any new software layer adds overhead to system

10 Hardware Virtual Machine Monitors Virtual machines are exported by thin layer of software, the VMM The hardware level VMM runs directly on the hardware and can export multiple VM s that look exactly like or similar to the real hardware

11 Main Concern of the VMM Biggest problem faced by the VMM is to present the hardware to the VM in a safe, transparent and efficient way Safe whatever the VM does, it should not be able to affect other VM s or the VMM Maintain illusion by tricking the software into thinking it has the hardware to itself and by hiding the true state of the hardware

12 Possible uses/benefits for using a hardware level VMM as a system administrator?

13 Some I Had Program testing and development Accelerated application deployment Using pre-configured virtual machines Data isolation One VM access secure data, one on a public network Server consolidation Used to run non trustworthy applications

14 More uses/benefits Implement resource monitoring within the VMM Reduce hardware costs Give root to an untrusted user (e.g., student) in a virtual machine rather than the physical one

15 VMware Hosted VMM Capable of extending modern operating system to support a virtual machine monitor that acts like a hardware level VMM Available for Windows or Linux as host OS Several different products Player (free) Workstation Server (free) Etc.

16 Xen Open source VMM developed by University of Cambridge Designed to be able to run 100 instances of OS s at the same time OS must be modified to run within Xen, due to paravirtualization Xen runs by having one OS in a privileged state called Domain-0 which is booted on start up and is then used to start all other unprivileged OS s in Xen

17 VMware vs. Xen VMware can run any x86 OS unmodified Xen provides better performance doesn t support Windows yet since it is illegal to modify Windows, more on this later Xen takes more work to get it up and running Xen is free and is being supported by the Linux community including Red Hat (Fedora)

18 QEMU Free software that acts similar to VMware, but is said to be faster on x86, supports more architectures as well (SPARC, MIPS, PowerPC, PowerMac, ARM) Seems far more complicated than VMware, but free

19 Countless Other Virtualization Technologies SimOS Microsoft Virtual Server Mac-on-Linux Linux-VServer OpenVZ Microsoft Virtual PC See

20 The Future Hardware companies have taken notice of virtualizations growing popularity and advantages Intel (called Virtualization Technology or VT-X Vanderpool) and AMD (Pacifica) are releasing processors that have built in software virtualization support that try to eliminate emulation costs This support will allow Xen to support unmodified unprivileged OS s (hello Windows support)

21 Questions?

22 Sources acmqueue.com/modules.php?name=content&pa=sh owpage&pid=168&page=1 ation.htm searchopensource.techtarget.com/originalcontent/0, ,sid39_gci ,00.html