Concept Guide

12 Memory Errors and Dell PowerEdge YX4X Server Memory RAS Features
Important: Consult your PowerEdge server installation and service manual for
complete memory population guidelines to properly enable Memory Mirroring.
Fault Resilient Memory (FRM)
Fault Resilient Memory Feature Support Table
CPUs Supported
Xeon Platinum and Gold SP Families Only
DIMMs Supported
x4 DIMMs: 
x8 DIMMs: 
Memory Configuration
Required
• Memory channels must be populated as either all one DIMM per
channel or two DIMMs per channel
FYI: Dell has published a separate technical whitepaper specifically for Fault
Resilient Memory.
Fault Resilient Memory (FRM) is a memory RAS feature that leverages partial memory mirroring to
create a fault resilient memory region specifically for critical memory functions. This will prevent any
uncorrectable errors in this memory region from generating a kernel panic or termination of virtual
machines or applications. A comparative advantage of FRM versus full memory mirroring is that the
memory capacity overhead can be configured based on need. The maximum memory redundancy
overhead for FRM is 25% compared to 50% with full memory mirroring.
When used with hypervisors such as VMware vSphere ESXi version 5.5 or later, the hypervisor will
ensure that only kernel memory and critical virtual machines utilize the mirrored memory region. In
BIOS Setup, a user may select to enable this feature with 12.5% or 25% memory redundancy. Separately,
the hypervisor must also be configured to utilize the mirrored memory region. Reference the Dell FRM
technical whitepaper for additional guidance.
When used with Linux operating systems that support address range or partial memory mirroring, the
OS will ensure that kernel memory utilizes the mirrored memory region. Since only the kernel will be
using the redundant memory space, the redundancy footprint for this usage model can big significantly
less than the hypervisor FRM configuration. In some cases, the redundancy footprint can be as little as
4GB of total memory. To configure this, a user must enable FRM in BIOS Setup selecting 12.5% or 25%
memory redundancy. Then, the user must configure the operating system to request a new mirrored
memory size. The OS request will override the static memory mirroring size specified in BIOS Setup. For
more information about support for this feature, see the production documentation of the respective
operating systems.
Important: Use of FRM is only officially supported by Dell with VMware vSphere
ESXi versions 5.5 or later (when used in conjunction with their Reliable Memory
feature). Use of FRM with Linux is not officially supported by Dell.