HP-UX vPars and Integrity VM V6.3 Administrator Guide

• The upper limit of the memory required for the guest must be available on the VSP.
• At run time, memory cannot be increased beyond the upper limit. To increase the limit, you
must shut down the VM guest and specify the required upper limit.
• If the Integrity VM guest is migrated online, the target must have the upper limit of specified
memory available.
NOTE: Dynamic memory is not applicable for vPar.
To illustrate this feature, it allows a VM that is a Serviceguard node to be used as a standby server
for multiple Serviceguard packages. When a package fails over to the VM, the VM memory can
be changed to suit the requirements of the package before, during, and after the failover process.
To use dynamic memory, the VM must have the VirtualBase software installed, as described in
Section 2.6.2 (page 35).
For more information about managing Integrity VM dynamic memory, see Section 13.14 (page 231).
5.6 Configuring memory for vPars
5.6.1 Memory allocation
When a vPar is started, the memory from the vPars and Integrity VM pool is allocated and presented
to the vPar as if it were private, physical memory. vPar memory is not virtualized, so, there is no
additional virtualization overhead involved in handling vPar memory. There is no hard limit on the
maximum memory configuration for vPars. Barring some overhead memory, the whole of available
memory that is present in the vPar and Integrity VM pool can be used by a single vPar.
5.6.2 Overhead memory for vPar
Each vPar has a memory overhead depending on its size. You can do a rough estimation of the
individual memory overhead using the following formula:
vPar memory overhead = vpar_mem * 0.4% + 64M
where, vpar_mem is the vPar memory size (in MB).
For example, a 16G, 8 CPU vPar, would have a memory overhead of 128M. The overhead
memory is constant for a given vPar memory configuration, irrespective of the CPU count. Hence,
in this example, even if it became a 16G 16 CPU vPAR, the memory overhead would remain
128M.
5.6.3 Online memory migration
Starting HP-UX vPars and Integrity VM V6.2 release, online addition and deletion of memory is
supported. This means that you can add and delete memory from a live vPar without rebooting
the vPar.
NOTE: The vPar OS must have the PHKL_43308 patch installed to use this feature. This patch
will be automatically installed as a part of the HP-UX 11i v3 March 2013 update on the vPar. If
you are running an HP-UX 11i v3 Version prior to March 2013 update on your vPar, you must
install this patch.
When memory is added to a live vPar:
• The VSP configures and presents the requested memory from the vPar and Integrity VM memory
pool to the vPar.
• The HP-UX kernel in the vPar discovers and integrates the new memory pages. Subsequently,
applications can use the new memory.
5.6 Configuring memory for vPars 59