CPU/Memory "Hot-Add" and "Hot-Remove" Support in Red Hat Enterprise Linux version 7

Updated -

Red Hat Enterprise Linux version 7.0 (RHEL7.0) and later supports "Hot-Add" of physical CPU and Memory as long as the underlying hardware supports this function.

Red Hat Enterprise Linux version 7.1 (RHEL7.1) and later supports "Hot-Remove" of physical CPU and Memory as long as the underlying hardware supports this function.

4 Comments

This feature doesnt work on my vanilla rhel 7 install. Which kernel module should be loaded for this to work?

I "onlined" the memory as follows:

echo online > /sys/devices/system/memory/memory[number]/state 

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1012764

This article specifically relates to physically adding or removing CPUs and/or memory on a physical system, not a system in a virtualized environment. The underlying hardware and firmware must support this function for it to be functional in Red Hat Enterprise Linux 7.1 and later.

For an example, see http://www.fujitsu.com/global/products/computing/servers/mission-critical/primequest/news/video/video-pq-201410.html

vCenter Server 6.5 Update 1g, and ESXi 6 patch 6 6921384. New VM, RHEL7.5, OS linux, RHEL7.5, open vm tools were in ISO image running 2147483647. I can hot add CPU fine. VM have 2 GB of RAM, I can hot-add up to 3 GB RAM. hot add 4GB or higher give error and won't let me do it in vCenter (memory must be between 2 GB and 3 GB. WHY? VMware Support says OS limiting this. Any help appreciated.