Reconfiguring vPars v6 memory with zero downtime
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• On a system with heavy amount of memory utilization, the HP-UX kernel might take minutes or even hours to evacuate
memory. Hence, it is advisable not to delete oating memory on a heavily loaded system. Such a constraint does not
exist while adding more memory. The system administrator can add memory anticipating higher memory utilization or
when the memory utilization begins to go up.
– When a vPar takes more time to delete or does not make forward progress on deletion, it may be helpful to cancel the
operation and split the single large memory deletion operation into two or more small memory deletion operations.
For example, if a partition contains a large amount of oating memory, instead of deleting all the oating memory
in one operation, it may help to split it into multiple smaller delete operations each consisting of 10% of oating
memory.
NOTE
Under very rare conditions, the kernel could consume some portion of oating memory during boot. In such a situation,
the portion of oating memory consumed by the kernel will be converted to base memory. When that happens, the guest
conguration le will be updated to reect the increase in base memory and decrease in oating memory for that vPar.
Granularity and memory modication
Granularity refers to the unit size in which memory is assigned to all the vPars. The memory granule size is xed at 64
MB. Hence, all memory operations are performed in multiples of this size. On a live vPar, a maximum of 255 granules can
be specied per memory operation. Therefore, the maximum amount of memory that can be added to or deleted from a
vPar in a single operation is 16,320 MB.
Memory is always migrated (either add or delete operation) in multiples of 64 MB granules. Hence if a memory migration
operation is initiated where the requested memory is not a whole multiple of 64 MB, the actual memory considered
for the operation will be round down to the previous granule size. For example, if a request is made for deletion of 100
MB of memory, only 64 MB will be deleted. If a 257 MB deletion is requested, 256 MB will be deleted. Similarly, if a 100
MB memory addition request is made, 64 MB will be added and not 100 MB. To minimize any unintended changes, it is
recommended to perform memory migration operations in terms of multiples of the granule size.
Technical white paper | HP-UX vPars and Integrity VM v6.2