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This shows you the differences between two versions of the page.

--- hardware:workflow:memtest [2025/08/11 11:00] – fabricio
+++ hardware:workflow:memtest [2025/09/01 17:11] (current) – removed fabricio
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-====== Isolating and Testing RAM Sticks in Ubuntu ======
-This guide explains how to:
-  * Boot using only **one RAM stick** (by reserving other address ranges via ''memmap='')
-  * Test the remaining sticks with ''memtester'' **inside the OS**
-  * Cycle through all sticks, including the originally "known good"
-  * Reset to the normal configuration afterwards
-==== 1. Finding a Bootable Stick ====
-If you are unsure which RAM stick works:
-  - Power down and remove all but one stick
-  - Insert into the **primary DIMM slot** (usually nearest the CPU — see your motherboard manual)
-  - Attempt to boot
-    * If the system posts and loads an OS, mark this stick **bootable**
-    * If not, swap in another stick and repeat until one works
-(For more on this isolation method, see [[https://help.corsair.com/hc/en-us/articles/14238510858637-RAM-How-to-Test-RAM-Modules-for-Memory-Issues|corsair.com]])
-==== 2. Determine Memory Layout ====
-  - With only the bootable stick installed, boot Ubuntu.
-  - Check stick size and slot mapping: <code bash> dmidecode --type memory</code>
-  - Record:
-    - Size of the good stick (e.g. 8 GiB)
-    - Number and sizes of all sticks when installed
-===== 3. Reserve the Other Sticks' Address Space =====
-  - Install all sticks.
-  - Edit GRUB: <code bash> sudo nano /etc/default/grub </code> In: <code> GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"</code> append: <code>memmap=<SIZE>$<START></code> Where:
-      * **SIZE** = total capacity of sticks to test
-      * **START** = address immediately after the main stick's range
-Example (8 GiB good stick, 24 GiB to test):
-<code>
-GRUB_CMDLINE_LINUX_DEFAULT="quiet splash memmap=24G$8G"
-</code>
-. Save, update GRUB, reboot:
-<code bash>
-sudo update-grub
-sudo reboot
-</code>
-**Sidenote on update-grub**:
-After editing ''/etc/default/grub'', running ''update-grub'' ensures the new memmap parameter is written to ''/boot/grub/grub.cfg''. Without this step, changes won't apply on reboot.
-**Verification:**
-After rebooting, check reserved memory with:
-<code bash>
-dmesg | grep -i memmap  # Kernel log should show reserved regions
-free -h                 # Available RAM should reflect the exclusion
-</code>
-===== 4. Verify Isolation =====
-<code bash>
-free -h
-</code>
-Should show only the good stick's capacity as usable by the OS.
-===== 5. Test the Other Sticks In‑OS =====
-Install and run:
-<code bash>
-sudo apt install memtester
-memtester <SIZE-TO-TEST>M 1
-</code>
-Where **SIZE-TO-TEST** ≈ reserved size.
-**Runtime note:**
-  * ''memtester'' inside Ubuntu can complete a pass over a portion of RAM in **minutes to under an hour**, depending on size tested — it only tests memory the OS can allocate at runtime ([[https://repair.wiki/w/Raspberry_Pi_RAM_Test|repair.wiki]])
-  * ''Memtest86+'' at boot is **much slower** — several passes can take **many hours or overnight** ([[https://rtech.support/docs/guides/memtest/memtest86|rtech.support]]), but it is far more thorough
-===== 6. Cycling Through Sticks =====
-Once a stick passes the in‑OS test:
-  - Shut down
-  - Move this passing stick into the **main** slot
-  - Move the previously main stick into the test slots
-  - Update the ''memmap'' parameters accordingly (good stick's size / address)
-  - Repeat testing
-This way, you can eventually test **every stick**, including the one you started with.
-===== 7. Restore Normal Operation =====
-. Edit ''/etc/default/grub'' and remove ''memmap=...''
-. Update GRUB and reboot:
-<code bash>
-sudo update-grub
-sudo reboot
-</code>
-. Verify all RAM is detected:
-<code bash>
-free -h
-</code>
-===== 8. Tips =====
-  * ECC RAM: Check ''journalctl -k | grep -i edac'' for logged correctable errors
-  * Label defective sticks immediately
-  * If several sticks fail in the same slot, suspect the slot or motherboard
-  * See [[https://help.corsair.com/hc/en-us/articles/14238510858637-RAM-How-to-Test-RAM-Modules-for-Memory-Issues|corsair.com]] for more on physically testing one stick at a time