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

NOTE: The VSP attempts to obtain memory from the vPar and Integrity VM memory pool, based
on the most favourable NUMA characteristics of the vPar. There are no manual controls to change
memory selection.
When memory is to be deleted from a live vPar:
• The HP-UX kernel in the vPar selects the memory pages to evacuate, and moves the contents
to other available free pages and then frees those memory pages.
• The VSP marks the memory as free, returns the memory back to the vPar and Integrity VM
memory pool, and this memory can be assigned to other vPars.
For more information about the online memory migration, see Reconfiguring vPars v6 memory with
zero downtime white paper at http://www.hp.com/go/hpux-hpvm-docs.
5.6.3.1 Base and floating memory
In HP-UX, portions of the memory, that contain kernel code and certain kernel data structures cannot
be evacuated. While allocating memory during boot or runtime, the HP-UX kernel needs to know
in advance, the memory type to use for kernel data structures as they cannot be evacuated. To aid
HP-UX kernel in this differentiation, vPars software sub divides memory into the following two types:
• base memory
• floating memory
NOTE: Base memory and floating memory is applicable only for vPars.
Base memory is used by the vPar HP-UX kernel for critical data structures. You can increase the
amount of base memory of a live vPar but you cannot decrease it.
Floating memory is typically used for user applications. You can either increase or decrease floating
memory from a live vPar.
For the list of command line options for base and floating memory configuration, see
Section 13.15.1 (page 240).
NOTE: The floating memory that is deleted from one vPar can be allocated to another vPar as
base or floating memory.
5.6.3.2 Allowed memory modification operations
Table 10 (page 60) lists the operations that are allowed for each memory type depending on the
vPar state.
Table 10 Types of memory
Floating memoryBase memoryvPar state
DELETEADDDELETEADD
AllowedAllowedNot AllowedAllowedOnline
AllowedAllowedAllowedAllowedOffline
For more information about illustrations and command line options related to vPar online memory
migration, see Section 13.15.3 (page 243).
5.6.3.3 Guidelines for base and floating memory configuration
The HP-UX kernel requires a certain percentage of total memory to be base memory for system
performance and to ensure that there is adequate memory available for critical system needs. The
60 CPU and Memory