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

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.
5.7 Memory allocation and usage for VMs and vPars—Implementation
notes
vPar and VM memory is allocated in granules of 64 MB. If a vPar's or VM's memory size is not
an even multiple of 64 MB, the API/CLI code rounds up, but hpvmapp rounds down. Consequently,
there will be 64 MB of memory reserved for the vPar/VM, but not used by it, and the vPar/VM
might have up to 64 MB to 1 KB of memory less than was allocated.
To work around this problem, set the vPar or VM memory size to a multiple of 64 MB.
Overhead memory calculations for a vPar and VM guests are different. A vPar always takes less
or same overhead memory than a VM guest with same configurations. If a vPar guest is converted
to a VM guest and if there is no sufficient memory to accommodate increased overhead memory,
the modified guest may not start.
62 CPU and Memory