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

(ram_dyn_max) in increments of the chunk size (64 MB). Use the -x option with the hpvmmgmt
command:
# hpvmmgmt -x ram_target=memory_size
For example, to change the guest memory size to 4 GB, enter the following command:
# hpvmmgmt -x ram_target=4096M
Attempting to increase memory from 2103 MB to 4096 MB.
Successfully began to change ram_target to 4096 MB.
13.14.3 Troubleshooting dynamic memory problems
This section describes how to solve problems in the use of dynamic memory.
13.14.3.1 Dynamic memory restrictions
Use of dynamic memory is subject to the following restrictions:
• The memory size of a VM cannot be increased to a value above its original boot size (as
specified with the -r option).
• If the VM memory has become fragmented, attempting to reduce the size of the VM might fail
or might take a very long time. If you cannot reduce the size of the VM to the desired size,
abort the operation by setting a new target size.
• Increasing the size of a VM requires free memory on the VSP. If the VSP memory is insufficient,
the operation might take a very long time to complete, and might fail.
• If the values of ram_target and ram_dyn_target_start are not within the values of
ram_dyn_min and ram_dyn_max, a warning message is displayed.
13.14.3.2 VM resource considerations
During normal operation of a system that has a workload running on it, the large pages might
become fragmented over time. This is true on the VSP and on a VM running the HP-UX operating
system. If the memory of the VM is fragmented, the dynamic memory subsystem is 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, the size is not reduced.
13.14.3.3 Specify sufficient VM memory
If you set the value of ram_dyn_target_start small, the guest operating system of the VM
might hang or crash while booting. In this case, the VM does not have access to 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 VM configured with 2 GB of memory
by more than 50%.
If the VM crashes while booting on the VSP, use the hpvmmodify command to increase the value
of the ram_dyn_target_start parameter. For example, to increase the memory size for the
VM named host1, enter the following command on the VSP:
# hpvmmodify -P host1 -x ram_dyn_target_start=2GB
After you set this parameter, reboot the VM.
If the VM hangs, on the VSP, use the hpvmstatus command to verify the memory statistics on
the VM. For example:
# hpvmstatus -V -P host1
.
.
.
[Dynamic Memory Information]
Type : driver
Minimum memory : 1222 MB
Target memory : 2103 MB
13.14 Managing dynamic memory from the VSP 237