Some info and items for XEN:#

• XenSource, Inc was acquired by Citrix Systems in October 2007

xm commands#

What is the difference between full virtualization and paravirtualization?#

Full virtualization #

Full virtualization (aka HVM) is called "full" because the entire system's resources are abstracted by the virtualization software layer. Individualization is called “para” because only a portion of the system's resources, or partial amount, is abstracted. Application programming interfaces (APIs) enable communication or provide assistance in certain situations.

• fully virtualized workloads leveraging Xen require that the host physical systems contain x86 virtualization.
• fully virtualized workloads do not require any change or modification to their guest operating systems.

Paravirtualization#

Paravirtualization requires that the guest operating system running on the host server be modified so that it recognizes the virtualization software layer.

Through paravirtualization, XEN can achieve higher performance than maybe possible on the host architecture (x86) which is not possible with traditional virtualization techniques.[1]

Is your Intel CPU utilizing VT-x extension?#

AFAIK, if anything is returned then is the result is positive.

(From my 2xCPU Quad4 box)
grep pae /proc/cpuinfo
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm
flags           : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc rep_good nopl pni ssse3 cx16 lahf_lm

is your AMD CPU utilizing Secure Virtual machine (or SVM) extension?#

AFAIK, if anything is returned then is the result is positive.

grep -i svm /proc/cpuinfo (No AMD running XEN)

is your XEN hypervisor capable of Hardware Virtual Machine (HVM)?#

AFAIK, if anything is returned then is the result is positive.

grep -i hvm /sys/hypervisor/properties/capabilities
xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64

XM Commands#

xm list#

 xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0 15527     8     r-----  52503.7
idp                                          1   512     4     -b----    175.9

Other useful xm commands include:#

• xm start starts a virtual machine
• xm reboot reboots a virtual machine
• xm destroy immediately terminates a virtual machine
• xm block-list displays all virtual block devices attached to a virtual machine
• All xm operations require that the Xen control daemon, xend, be running. For this reason, you should make sure xend starts whenever the host boots.
• Most xm commands require root privileges to allow interaction with the Xen hypervisor. Entering the xm command when you are not logged in as root returns an error.
• Some xm commands return no information even though the action is completed. In some instances, for example, when shutting down a virtual machine, the action can take several seconds to complete. To verify that the action has completed, you might need to view its status another way, such as, using the xm list command. [#1] http://en.wikipedia.org/wiki/Xen