ESXi Reliable Memory Technology

VMware has introduced new feature for kernel protection against memory error in ESXi. VMware called the new feature: Reliable Memory Technology or RTM.

The feature is one of new features in ESXi 5.5!

ESXi use a zone of memory that it’s more reliable than other offsets of memory, so risk of PSOD will be reduced. Also when part of memory has error, ESXi will stop to using the part of memory.

There is some other technique against memory corruption or memory health error such as memory mirroring but Reliable Memory Technology can help you on this regard without loosing half of your memory capacity. Because memory mirroring is just like to RAID 1 on hard disks.

Dell has introduced another feature on its server by using Reliable Memory Technology and called the new feature: Fault Resilient Memory or FRM.

Fault Resilient Memory will provide “Fault Resilient Zone” and ESXi will put its kernel to the zone.

The features can protect ESXi kernel and VMs as well. So if you have critical service on a VM, you can force ESXi to keep its memory on RTM or FRM zone to avoid memory error and down time for the machine.

You can configure RTM on your VM by follow the below instruction:

sched.mem.reliable is the VMX option to on to place the memory pages consumed by a virtual machine to reliable memory area.

This is a Per-virtual machine basis option. The default value is False.


To turn on the feature:

  1. Edit the .vmx file
  2. Add the parameter:
  3. sched.mem.reliable = “True”

Note: sched.mem.reliable is just a flag to prefer reliable memory. It’s not guaranteed that all memory pages consumed by the virtual machine are allocated from reliable memory regions on the server platform.

To turn off the feature:
  1. Edit the .vmx file
  2. Add the parameter:

sched.mem.reliable = “False”


Note: vSphere Reliable Memory feature only works on the server platforms which supports Reliable Memory technology. Please contact server manufacturers for details.

I couldn’t find any document for other vendors such as HPE, IBM and others.

Davoud Teimouri

Davoud Teimouri is as a professional blogger, vExpert 2015/2016/2017/2018/2019, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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