HP-UX vPars and Integrity VM V6.1.5 Administrator Guide (5900-2295, April 2013)

• Balancing VSP workloads
• Optimizing physical resource utilization
With Online VM Migration, you can migrate all your VMs off of a VSP to one or more other VSPs
without interrupting the workload activity on the virtual machine. A common reason to do this is
for maintenance of the VSP system: hardware, firmware or software. You can configure the hardware
that does not have hot-plug support. You can update the firmware, which requires the system to
be shut down. You can also update software components that require a VSP reboot. A rolling
upgrade of VSP software is possible by moving the running guests to another VSP, upgrading the
VSP, then migrating the guests back. Being able to move VMs while keeping active applications
online allows greater flexibility in scheduling maintenance or upgrades, and minimizes the impact
of unpredictable maintenance. For example, you can move online VMs in response to predictive
failure alerts without interrupting your applications.
You might also want to migrate an active VM workload to a particular VSP to take advantage of
a particular resource or feature on that target VSP without losing application availability. If your
current VSP resources become oversubscribed, you can migrate one or more of the VMs to other
VSPs that have remaining capacity. Perhaps a potential target VSP has a large quantity of RAM,
CPUs or I/O adapters, which might facilitate faster processing or greater I/O bandwidth while
on that VSP. Another possibility is that certain VSPs have special devices that are needed only
temporarily by VM workloads. Because Online VM Migration enables VMs to be migrated without
interrupting their workloads, it is convenient and practical to migrate VMs temporarily to certain
VSPs to take advantage of their particular resources and features when they are needed. This is
especially true for workloads with well-understood cyclic resource requirements (for example,
month-end processing).
You might want to segregate VMs to balance the workload on VSPs workloads. For example, you
might want to separate VMs whose workloads peak simultaneously. Or, perhaps you want to
group workloads together that have similar special resource requirements. For example, you would
usually run your multi-threaded applications on a VSP that has several CPUs in order to maximize
the effectiveness of multi-way virtual machines. Online VM Migration enables a new level of
workload-to-resource alignment flexibility and agility -- you can segregate or combine your workloads
as you wish, without any interruption in application availability.
The Online VM Migration feature enables you to optimize the physical resources being used by
running VM. You can conveniently "park" idle, near-idle, or just currently less-critical VM workloads
together on a smaller or less powerful machine. You can use the dynamic memory feature to reduce
the amount of memory in use by the VMs and shrink CPU entitlements to more tightly packed VMs
on a smaller VSP.
Table 31 provides the supported online migration paths for HP-UX guests:
Table 31 Online Forward Migration Paths
Supported Forward Migration PathIntegrity VM Version
Integrity VM V4.2Integrity VM V4.1
Integrity VM V4.2.5, Integrity VM V4.3, V6.1, and Integrity
VM V6.1.5
Integrity VM V 4.2
Integrity VM V4.3, Integrity VM V6.1, and Integrity VM
V6.1.5
Integrity VM V4.2.5
Integrity VM V6.1 or Integrity VM V6.1.5Integrity VM V4.3
Integrity VM V6.1.5Integrity VM V6.1
Online migration among Integrity servers is limited by the processor architecture. Online migration
among servers with processor family 31 is supported regardless of the model number within the
family. Migration among servers with processor family 32 and model numbers 0 or 1 is supported.
12.1 Introduction to migration 201