HP-UX Virtual Partitions Administrator's Guide (includes A.05.02)

CPU, Memory, and I/O Resources (A.04.xx)
Granularity Issues (Integrity and PA-RISC)
Chapter 7
252
Careful configuration planning will avoid this situation.
Granularity limitations do not apply to PA-RISC platforms.
However, there are guidelines that do apply to both PA-RISC and
Integrity systems. These are described next.
+ Recommendations for ILM and CLM granularity specifications:
On PA-RISC platforms, each vPar needs ILM below 2 GB to load and
launch its kernel. However, portions of the first granule
(starting at address 0) are used for the Monitor's code and data,
therefore will not be used for the kernel. Hence, excluding the
first granule, there should be at least one granule below 2 GB for
each partition. So if ILM granularity is 128 MB, the first 2 GB
will consist of 16 granules. Therefore, it will be possible
to load and launch the maximum supported 8 vPars. If ILM
granularity is 256 MB, there are only 8 granules in the first 2 GB.
The Monitor uses portions of the first one. So it will only be
possible to load and launch 7 or fewer vPars. On ab Integrity
server, there is no similar constraint on the maximum ILM
granularity.
For CLM on PA-RISC platforms, and for both ILM and CLM on
Integrity systems, Hewlett-Packard recommends choosing the
largest possible granularity for performance reasons. The
granularity can be such that it is equal to the partition with the
least amount of that memory type. For example, if the system
contains 64 GB of ILM and the smallest ILM specification of any
vPar is 1 GB, then ILM granularity can be 1 GB. If the system
contains 64 GB of CLM per cell and the smallest CLM specification
from any cell of any vPar is 4 GB, the CLM granularity can be 4 GB.
+ For an Integrity server, the chosen granularity values must
also be written to system firmware storage. When the Monitor is
started and a vPar database is loaded, the values in the database
must match those in firmware, or the Monitor will not allow the
database to be used.
While in nPars mode, you should use the vparstatus and vparenv
commands to verify that the database and firmware granularities are
identical. If not, you must either create a new database with the
correct granularities using the vparcreate -g command, or change
the firmware granularities with the vparenv -g command.
Although memory is normally allocated in integral granules, some
memory ranges are withheld for use by the Monitor or by firmware. The
vparstatus -m command displays these ranges. Other ranges of address
space are simply non-existent. Because of this fragmentation, the
Monitor may assign your vPar slightly more or less than an integral
granule of memory when the vPar boots.