Memory: Choosing a Granularity Value and Boot Time (Integrity)

The Goal

The goal to avoid slow boot times is to have the number of granules to be close to 50. Any quantity up to 100 will show reasonable boot times, but HP recommends a value close to 50.

Example 1

If the total physical memory in the nPartition is 12 GB, then the granularity value should be 256 MB:

Example 2

If the total physical memory is 100 GB, then the granularity value should be 2 GB:

Note that as seen in “Granularity Issues (Integrity and PA-RISC)” and in the vparresources(5) manpage, memory is allocated to a virtual partition as a multiple of the granularity value. In this example, given a granularity value of 2 GB, this means that every virtual partition will have at least 2 GB (1 multiple) allocated to it. Further, this means that any memory assigned between the multiples will be rounded up to the next multiple. For example, if you attempt to assign 3 GB of memory to a virtual partition, this actual memory allocated will be rounded up to the next granularity multiple, in this case, of 4 GB.

If having each virtual partition allocated with at least 2 GB of memory is not desired, then you must chose a granularity value that is less than 2 GB, noting that this will cause the number of granules to be higher than 50 and therefore increase boot time.

	NOTE: PA-RISC  Due to PA-RISC and Integrity architectural differences, the way memory is presented to HP-UX on PA-RISC systems is different than on Integrity systems, so PA-RISC systems do not encounter this slow boot issue.