HP-UX Virtual Partitions Administrator's Guide (includes A.03.05 and A.04.05)

Granularity
Memory is normally assigned to vPars in units called granules.
Exceptions are described below. The granule values for CLM and ILM
can be different. However, both are subject to the following rules:
+ MOST IMPORTANT, READ CAREFULLY. Granularity, the value of a
granule specification, is not a resource. Resource assignments can
be modified, even if some resource modifications require that a
vPar be Down. Granularity can only be specified when creating a
new database. It cannot be changed thereafter.
+ The minimum values (ILM and CLM) are 64 MB.
+ The default values are 128 MB.
+ The recommended specifications are described below.
+ Any chosen granularity must be an integral power of 2, not just a
multiple of 64. For example, 256 is a legal value, but 192 is not.
+ Although a granularity must be an integral power of 2, memory can
be assigned in any multiple of that value. For example, if the CLM
granularity is 128 MB, it is legal to assign 384 MB of CLM to a
vPar.
+ Integrity systems have a platform-dependent limit to the
number of CLM granules per cell or ILM granules that may be
configured. You can determine specific limits for your
installation by using the vparenv command and examining the "The
maximum possible xLM granules..." messages. Note: When in nPar
mode, the vparenv command does not display the "The maximum
possible xLM granules..." messages if the next boot mode setting is
nPars. So in order to get these values, you have to first change
the next boot mode setting to vPars (reboot not required) and then
invoke the vparenv command. These values, combined with your total
memory of each type, determine the minimum granularities you should
specify in order to allow your vPars to boot. For example, if you
are allowed 1024 ILM granules and your total memory is <= 128 GB,
you can use the default ILM granularity of 128 MB. Or if you are
allowed 16 CLM granules per cell, and your nPar configuration
includes two cells each configured with 8 GB of CLM, your CLM
granularity must be >= 512 MB.
If the total ILM memory or CLM memory per cell exceeds that which
can be configured in the maximum number of granules using your
specified granularity, the vPar Monitor will not boot any vPar. In
this case, you must increase one or both granularities
appropriately so that all available memory can be accommodated.
This will require a complete reconfiguration of your database.
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
220 CPU, Memory, and I/O Resources (A.04.xx)