How to Disable NUMA in CentOS / RHEL 6,7?

NUMA stands for non uniform memory access.In this architecture, memory access time depends on the memory location relative to a processor.
Some workloads and virtualization setups perform more predictably when NUMA is turned off.
This guide explains how to disable NUMA on CentOS and RHEL versions 6 and 7.

Prerequisites

Before you begin:

• Root or sudo access
• Comfort editing system configuration files
• A running CentOS/RHEL 6 or 7 server

1. Verify NUMA Status

First check if NUMA is enabled:

numactl --show

If you see output showing multiple memory nodes, NUMA is active.
You can also list memory nodes:

ls /sys/devices/system/node

If you see directories like node0, node1, NUMA is enabled.

2. Disable NUMA on CentOS / RHEL 6

On version 6 you edit the legacy GRUB configuration:

sudo vi /boot/grub/grub.conf

Find the line that begins with kernel under the default boot entry.
At the end of that line, add numa=off.

kernel /vmlinuz-2.6.32-754.el6.x86_64 ro root=/dev/mapper/centos-root rhgb quiet numa=off

Save the file and reboot:

sudo reboot

3. Disable NUMA on CentOS / RHEL 7

Version 7 uses GRUB2:

sudo vi /etc/default/grub

Locate the line starting with GRUB_CMDLINE_LINUX and append numa=off inside the quotes.

GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rhgb quiet numa=off"

Regenerate the GRUB configuration:

# For BIOS systems
sudo grub2-mkconfig -o /boot/grub2/grub.cfg

# For UEFI systems
sudo grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg

Reboot the server:

sudo reboot

4. Verify Changes

After reboot, confirm NUMA is disabled:

numactl --show

You should see output indicating a single memory node.
You can also check kernel messages:

dmesg | grep -i numa

Look for a line such as NUMA: Disabled.

Conclusion

You have successfully disabled NUMA on your CentOS or RHEL 6 or 7 system.
This change can improve consistency for certain applications and virtualization setups.