HP-UX Virtual Partitions Administrator's Guide (includes A.05.02)

Introduction
What Is vPars?
Chapter 1
20
• Processing resources and memory available at boot time can be added to or removed from a virtual
partition without rebooting.
Why Use vPars?
The following are some of the advantages of using vPars. Note that some of these features, such as dynamic
memory migration, are only available in more recent releases.
vPars Increases Server Utilization and Isolates OS and Application Faults
In certain environments, one entire server is dedicated to a single application. When demand for that
application is not at peak, such as during non-business hours, the server is underutilized. If many servers are
configured this way, you have many servers that are being underutilized. You can minimize investment and
operational costs by consolidating servers and running multiple applications on one server; however, this
leaves all applications vulnerable to problems if any one application or its single OS has problems.
vPars provides a software-based solution that supports isolating an OS and its applications within virtual
partitions; thus, OS or application problems in one virtual partition do not affect the OS or applications
running in other partitions.
vPars also allows consolidation of underutilized servers into one faster server where applications are not
permitted to affect one another, such as an ISP running many small e-services application servers.
vPars Provides Flexibility Through Multiple but Independent OS Instances
vPars offers flexibility by allowing different HP-UX instances, OS Releases, and patch levels to run on the
same server.
vPars Provides Flexibility Through Dynamic Processing Core and Memory Migration
vPars enables you to reassign processing resources and memory from one virtual partition to another without
rebooting.
Processing cores and memory can be moved between two virtual partitions that have different resource
utilization peak times. For example, a transaction server used primarily during business hours can have a
portion of its cores and memory reassigned overnight to a report server. Such reassignments can be
automated, for example, via a cron job.
Because vPars assigns specific hardware resources to specific virtual partitions, a user on the transaction
server at night is not affected by the processing power consumption of a report server. A virtual partition uses
only the cores and memory that you assign to it; cores are not time-sliced across virtual partitions.