How to check if system RAM is faulty in Red Hat Enterprise Linux?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL)
  • x86 (32 or 64 bit)

Issue

  • How to check if system memory (RAM) is faulty in Red Hat Enterprise Linux?

Resolution

  • Red Hat Enterprise Linux ships a memory test tool called memtest86+. It is a bootable utility that tests physical memory by writing various patterns to it and reading them back. Since memtest86+ runs directly off the hardware it does not require any operating system support for execution.

  • This tool is available as an RPM package from Red Hat repositories as well as a boot option from the Red Hat Enterprise Linux rescue disk.

  • To boot memtest86+ from the rescue disk, you will need to boot your system from CD 1 of the Red Hat Enterprise Linux installation media, and type the following at the boot prompt (before the Linux kernel is started):

    boot: memtest86

  • If you would rather install memtest86+ on the system, here is an example of how to do it on a Red Hat Enterprise Linux 5 and above versions:

    # yum install memtest86+

  • Then you will have to configure it to run on next reboot:

    # memtest-setup

  • After reboot, the GRUB menu will list memtest. Select this item and it will start testing the memory.

    • Please note that once memtest86+ is running it will never stop unless you interrupt it by pressing the Esc key. It is usually a good idea to let it run for a few passes so it has time to test each block of memory several times. With large memory situations it may take more than 10hours just to reach one pass.

  • If your system is UEFI only, you may evaluate the upstream release of memtest86+ v.6: memtest86+ v.5 shipped by Red Hat works only with systems booting in BIOS mode.

    • NOTE: Not being delivered by Red Hat, no support, implicit or explicit can be expected by using memtest86+ v.6.

  • memtest86+ may not always find all memory problems. It is possible that the system memory can have a fault that memtest86+ does not detect.

Root Cause

  • A common cause for needing to run memtest86+ is when the system suffer from degraded performances, unresponsive or panics repeatedly, and the logs show "Machine Check Exception".

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