How to disable NUMA (Non-Uniform Memory Architecture) on CentOS/RHEL 6

1. To disable NUMA, add numa=off to the kernel line in /boot/grub/grub.conf, for example:

# vi /boot/grub/grub.conf
kernel /vmlinuz-2.6.39-400.215.10.el5uek ro root=/dev/VolGroup00/LogVol00 numa=off

2. Reboot the server for the changes to take effect:

# shutdown -r now

Verify after rebooting the server:

# cat /proc/cmdline
ro root=/dev/VolGroup00/LogVol00 numa=off

3. You can also use the “numactl” command to verify the NUMA status:

# numactl -H
 available: 1 nodes (0)
 node 0 size: 4195 MB
 node 0 free: 3304 MB
 node distances:
 node 0
  0: 10

If NUMA was active, there would be more than one node listed in the above command output.