Specifications

Chapter 3. Virtualization 143
migration to fail. During the migration, the managed console controls all phases of
the process.
Improved Live Partition Mobility benefits
The possibility to move partitions between POWER6 and POWER7 processor-based servers
greatly facilitates the deployment of POWER7 processor-based servers, as follows:
򐂰 Installation of the new server can be performed while the application is executing on a
POWER6 server. After the POWER7 processor-based server is ready, the application can
be migrated to its new hosting server without application down time.
򐂰 When adding POWER7 processor-based servers to a POWER6 environment, you get the
additional flexibility to perform workload balancing across the entire set of POWER6 and
POWER7 processor-based servers.
򐂰 When performing server maintenance, you get the additional flexibility to use POWER6
Servers for hosting applications usually hosted on POWER7 processor-based servers,
and vice versa, allowing you to perform this maintenance with no application planned
down time.
For more information about Live Partition Mobility and how to implement it, see IBM
PowerVM Live Partition Mobility, SG24-7460.
3.4.6 Active Memory Sharing
Active Memory Sharing is an IBM PowerVM advanced memory virtualization technology that
provides system memory virtualization capabilities to IBM Power Systems, allowing multiple
partitions to share a common pool of physical memory.
Active Memory Sharing is only available with the Enterprise version of PowerVM.
The physical memory of an IBM Power System can be assigned to multiple partitions either in
dedicated or shared mode. The system administrator has the capability to assign some
physical memory to a partition and some physical memory to a pool that is shared by other
partitions. A single partition can have either dedicated or shared memory:
򐂰 With a pure dedicated memory model, the system administrator’s task is to optimize
available memory distribution among partitions. When a partition suffers degradation
because of memory constraints and other partitions have unused memory, the
administrator can manually issue a dynamic memory reconfiguration.
򐂰 With a shared memory model, the system automatically decides the optimal distribution of
the physical memory to partitions and adjusts the memory assignment based on partition
load. The administrator reserves physical memory for the shared memory pool, assigns
partitions to the pool, and provides access limits to the pool.
Active Memory Sharing can be exploited to increase memory utilization on the system either
by decreasing the global memory requirement or by allowing the creation of additional
partitions on an existing system. Active Memory Sharing can be used in parallel with Active
Memory Expansion on a system running a mixed workload of several operating system. For
example, AIX partitions can take advantage of Active Memory Expansion. Other operating
systems take advantage of Active Memory Sharing.
For additional information regarding Active Memory Sharing, see IBM PowerVM Virtualization
Active Memory Sharing, REDP-4470.