My Wasta Linux machine has been freezing at seemingly random moments. (Not slowing down; only freezing to the point where it won't respond to any interrupts except a hard restart.)

I'm running Memtest86+ to help me diagnose the issue, and I expected it to take a while, but it's already been 13 hours with no end in sight. There's other work that I need to get done.

Is it okay to interrupt Memtest86+ while it's running without adversely affecting the machine?

  • 19
    Yes, absolutely. You can press Esc to cause a reboot first, if that makes you feel better. But there's nothing wrong with yanking the plug while running Memtest86+. All it does is read/write from the RAM, which as you already know, is volatile once power is removed.
    – Cody Gray
    Jun 7 '17 at 12:40
  • 1
    If the machine is freezing but without a kernel error (check kernel logs after reboot) then your disk may be failing. Jun 7 '17 at 17:56
  • I had a similar issue (freezing to the point where it won't respond to any interrupts except a hard restart) except in my case a reboot didn't always help. I reseated the RAM and I haven't had problems since.
    – Ploni
    Jun 7 '17 at 23:16

If you're talking about memtest86/memtest86+, as in the bootable programs, sure. Interrupting it won't do anything, since it never writes any persistent data. In fact, the tests are intentionally endless - it'll just keep running passes until you stop it.

memtest is structured as a number of tests, each of a specific pattern. A single completed run through all selected tests is known as a pass. As mentioned before, you can safely abort at any time, simply by switching off the machine.

There is no optimal number of passes - an obvious failure will be caught in the first pass, while intermittent failures might take a hundred passes to appear (at which point you might as well get ECC RAM). I used to recommend running at least 10 passes to catch the more common intermittent failures, though with larger RAM capacities these days it could take too long.

  • 2
    Is an intermittent failure more likely to show up in 10 consecutive passes or could I also run 1 pass per day over a period of 10 days and use the machine for other stuff in between passes? Jun 7 '17 at 15:25
  • 7
    Running 10 consecutive passes is better, since an continuous and lengthy memtest86 run can pick up errors caused by overheating. Other than that, I believe that once a complete pass is completed all the consecutive passes are identical.
    – Arnon
    Jun 7 '17 at 16:34
  • 3
    I tend to run it for "as long as possible" which is at least overnight, maybe a weekend. "number of passes" doesn't really come into it.
    – Criggie
    Jun 7 '17 at 20:08
  • ECC memory: Fallen out of favor. Jun 8 '17 at 16:50

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