HP Integrity Virtual Machines Installation, Configuration, and Administration

9.6.3.3 Guest Performance Considerations
During normal operation of a system which has a workload running on it, the large pages may
become fragmented over time. This is true on the VM Host as well as a virtual machine running
the HP-UX operating system. If the virtual machine's memory is fragmented, the dynamic memory
subsystem will be unable to reduce the size of guest. This is due to the minimum chunk size
used for the reduction. If dynamic memory cannot remove at least 64 MB of physically contiguous
guest memory, no reduction in size takes place.
9.6.3.4 Specify Sufficient Guest Memory
If you set the value of ram_dyn_target_start too small, the guest operating system might
hang or crash while booting. In this case, the guest does not have access to a sufficient amount
of memory. As a rule, do not decrease the memory allocated to an HP-UX guest by more than
75% of its allocated memory size. Do not reduce the memory of a virtual machines configured
with 2 GB of memory by more than 50%.
If the guest crashes while booting, on the VM Host , use the hpvmmodify command to increase
the value of ram_dyn_target_start. For example, to increase the memory size for the guest
named compass1, enter the following command on the VM Host:
# hpvmmodify -Pcompass1 -x ram_dyn_target_start=2G
After you set this parameter, reboot the guest.
If the guest hangs, on the VM Host, use the hpvmstatus command to check the memory statistics
on the guest. For example:
# hpvmstatus -V -P compass1
.
.
.
[Dynamic Memory Information]
Type : driver
Minimum memory : 1222 MB
Target memory : 2103 MB
Maximum memory : 6144 MB
Current memory : 2103 MB
Comfortable minimum : 2167 MB
Boot memory : 6135 MB
Free memory : 0 MB
Available memory : 286 MB
Memory pressure : 100
Memory chunksize : 65536 KB
Driver Mode(s) : STARTED ENABLED
.
.
.
An indication of this problem is a small or zero amount of free memory and a large memory
pressure value (100). If these indicators are present, use the hpvmmodify command on the VM
Host to increase the memory size of the guest . The guest should then boot normally.
9.6.3.5 Actual Memory Allocations May Differ
If you specify a value of ram_target or ram_dyn_target_start that results in a change in
memory size that is not a multiple of 64 MB, the target value is reset.
For example, if you specify r 6 GB, the HP-UX guest actually has access to 6135 MB of memory.
If you modify the virtual machine, decreasing the amount of memory to 2048 MB, the amount
of memory actually removed is 4087 MB. If you set the value of ram_target to 2048 MB, the
value is reset to 2103 MB. Therefore, the actual amount of memory allocated is a multiple of the
chunk size.
126 Managing Guests