Fujitsu M10-1: Changing Memory Configurations Considerations

Asset ID:	1-72-1981987.1
Update Date:	2018-03-01
Keywords:

Solution Type Problem Resolution Sure

Solution 1981987.1 : Fujitsu M10-1: Changing Memory Configurations Considerations

Applies to:

Fujitsu M10-1 - Version All Versions and later
Information in this document applies to any platform.

Symptoms

Fujitsu M10-1 system can't see sections of memory after physically altering the memory configuration.

Changes

System (OVM) cannot identify sections of memory, when:

it is an M10-1, and
domain configuration is NOT “factory default” (which means, domain configuration is changed from the default), and
memory interleave is changed by “modifying memory configuration”

Modifying memory configuration means either:

Number of DIMMs in either group (group-A / B) is changed from 4 to 8, or 8 to 4, or
Capacity of 8 DIMMs in either group (group-A / B) is changed from the same capacity to the different capacities (such as “eight 8GB DIMMs” to “four 8GB DIMMs and four 16GB DIMMs”), or from the different capacities to the same capacity)

Because M10-4/4S is always working with multiples of 8 DIMMs with the same capacity this issue won’t happen.

Cause

This happens because the MAC ( Memory Access Controller ) requires different settings for “8 DIMMs with same capacity” or for “4 DIMM” / “4DIMM + 4DIMM (with different capacities)”.

When this setting is changed, the PA (Physical address) for specific DIMMs will be changed. Because the PA is changed, some domains may lose access to some of the memory bound to the domain.

In significant cases, the system may fail to start, and revert to factory-default.

Solution

To avoid or fix this issue, follow the below procedure when modifying the memory configuration:

Save domain configuration to the xml file
- # ldm list-constraints -x > {file.xml}
Set system to factory-default
- # ldm set-spconfig factory-default
Shutdown and power off the control domain
- #shutdown -i0 -g0 -y
- XSCF>poweroff -p 0
Modify the memory configuration
Power on and boot the control domain
- poweron -p0
- console -yp 0
- boot ( if auto-boot? is not set to true )
Confirm the system is started with "factory-default" setting after domain has started
- ldm ls-spconfig
Execute the ldm-init command to restart the control domain with the saved
configuration.
- # ldm init-system -r -i {file.xml}

Note: If the physical resource is used for memory (specific PA is assigned to some domain, rather than specifying size of memory to assign), administrator may need to adjust assigned memory based on new memory layout.

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