memtest86 Command: Tutorial & Examples

Checkin RAM for errors

The memtest86 command is a robust utility in Linux that checks your system's RAM for errors. This command is extremely vital as it helps in troubleshooting hardware problems that could be causing system instability, crashes, and data corruption.

As a Linux server administrator, understanding how to use the memtest86 command is crucial for maintaining system stability and performance. This command can diagnose potential memory issues that can lead to high load, system crashes, or even data corruption.

How memtest86 Works

The memtest86 software works by writing test patterns to every memory address, then reading back these patterns to verify the integrity of your RAM. It pushes your memory to its limit, carefully checking for errors. It's a standalone program that boots from a USB or CD and tests the RAM in your machine for faults using a series of comprehensive algorithms and test patterns.

Why memtest86 Is Important

Memory errors can cause serious system problems such as random reboots, system hangs, or even data corruption. It's often hard to diagnose these issues, as they can appear sporadically and may be mistaken for software bugs. By using memtest86, you can isolate these problems and potentially save hours of troubleshooting.

Typical Problems Solved by memtest86

Running memtest86 can help in diagnosing memory-related issues such as:

  • Random system crashes or reboots
  • Unexplained system slowness
  • Programs crashing unexpectedly
  • Operating system not booting

Using the memtest86 Command

The memtest86 command is typically found in GRUB, the boot loader for many Linux distributions. It's not a command you run in a shell, but rather a program that you boot your computer into.

sudo reboot

When your system reboots, select memtest86 from the GRUB menu. The test will start automatically.

Please note, memtest86 can take a long time to complete, especially with larger amounts of RAM. It's recommended to run this test when you don't need to use the computer, such as overnight.

Understanding memtest86 Output

When running memtest86, you'll see a series of tests being performed on your screen. If the test finds an error, it will be displayed like this:

Tst  Pass   Failing Address          Good       Bad     Err-Bits  Count Chan
---  ----  -----------------------  --------  --------  --------  ----- ----
8     0     0000893f7d0 -   137.0MB  ffffffff  fffffeff  00000100    1 

This output indicates that an error was found in the memory address 0000893f7d0. The "Good" column shows the expected result, the "Bad" column shows the value that was actually read, and "Err-Bits" shows the difference.


In conclusion, memtest86 is an invaluable tool when it comes to diagnosing and troubleshooting memory-related issues in your Linux server. It's a robust tool that can save a lot of time and prevent potential data loss caused by faulty hardware.

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