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Advantages:
• High performances• Affordable, low cost solution• Robust and easy to use• Easy to deploy• Simple management and implementation of virtual
machine• Multi-os support enables windows and Linux virtual
machines• Board industry support amongst leading manufacturer
including IBM, INTEL, HP • Wider local storage support• Deep hardware virtualization integration
XEN architecture
Xen-Domain0
Host OS
Xen-DomainU
Xen Virtual Machine Monitor (VMM)
H a r d w a r e
Guest OS
PinOS
1
To run PinOS between guest and hardware: Use Xen
Virtualize and present a fake processor to the guest OS
12
2PinTool
I/O
Engine
CodeCache
Processor architecture
• Table 2.3 Xen Features by CPU Architecture
• x86 x86 x64 • Feature (no PAE) (with PAE) (x86_64) IA-64 POWERPC
• Privileged Domains X X X X X
• Guest Domains X X X X X • • SMP Guests X X X X
• Save/Restore/Migrate X X X X • • More than 4GB RAM X X X X
• Progressive PV X X X X X
• Driver Domains X X X •
Paravirtualization • Table 2.4 Paravirtualization Requirements and Considerations
• Item Type item Requirements or special Consideration
• Memory Management Segmentation Cannot insert privileged segment descrip-
• tors and cannot overlap with the top end • of the linear address space. • Paging Guest operating system has direct read • access to hardware-level page tables,
• updates are batched or performed indi- • vidually and validated by the hypervisor.
• CPU Protection The guest operating system must run at a • more restricted privilege level than Xen—
• in other words, it cannot run in Ring-0.
• Exceptions The guest operating system must register • a table for exception trap handlers.
•
Continued…
• System calls The guest operating system may install a • handler for system calls, allowing direct • calls from an application or the operating • system itself. Some of these calls do not • need to be handled directly by Xen.
• Interrupts Hardware interrupts are replaced with a • notification event mechanism.
• Time The guest operating system must be • aware
• Device I/O Network Virtual devices are simple to access. Data • and Disk is transferred using asynchronous I/O • rings, and interrupt-like communication • to the guest operating system is handled • through event notifications.
virtualization
• CPU – Cpu virtualization– Cpu scheduling– Time
• Memory management– Memory allocation– Paging and segmentation– Virtual address translation
• I/o virtualization – Device i/o ring– Event channels– Virtual i/o devices and split device driver– Software and hardware iommu
Creating virtual machine
• Using a template file• Installing from a CD or an ISO image onto a
XEN virtual machine (windows 2003 and windows xp only)
• Installing from vendor media onto a network installation server directly onto a XEN vm
• Performing a physical to virtual convertion on an existing server
• Cloning an existing VM• Importing an existing exported XEN VM
conclusion
• Great performances with minimal overhead
• Hardware virtualization extension
• Easy to use, robust and affordable
• Benefits of server utilization
REFERENCES
• www.xensource.com
• www.wikipedia.org
• www.xenenterprise.com
• www.xenserver.com
• www.gosephtechnologies.com
• Linux for U