Maintenance purchase for 2025-05

List of components we would need to buy.

doc/2025-05-maintenance-purchase.md

@@ -0,0 +1,156 @@
+# Maintenance purchase 2025-05
+
+We need to buy some components to replace broken parts or to have spare ones for
+when they break. We also need some tools to do basic repairs.
+
+Here is the list:
+
+- 11 x Power supply DELTA DPS-750XB A (700 W) (this is critical)
+  - 57.69€/unit, 634.59€ total <https://es.aliexpress.com/item/1005004090017186.html>
+
+- 8 x RAM DDR4 2400MHz PC4-19200 ECC Registered
+  - 128.85€/pair, 515.40€ total <https://www.amazon.es/PC4-19200-REGISTERED-MEMORY-WORKSTATIONS-MOTHERBOARDS/dp/B06W9P3RKF>
+
+- 1 x Set of screwdrivers
+  - 23.99€ <https://www.amazon.es/BLOSTM-Juego-Destornilladores-Profesionales-Destornillador/dp/B09W9R8J3S>
+
+- 1 x UART adaptor
+  - 14.99€ <https://www.amazon.es/DSD-TECH-SH-U09C5-convertidor-Soporte/dp/B07WX2DSVB>
+
+- 1 x SSD SATA disk of 2 TB
+  - 135.99€ <https://www.amazon.es/Crucial-BX500-pulgadas-interno-CT2000BX500SSD101/dp/B0CCN9QWKT>
+
+Total: 1324.96 €
+
+# Rationale
+
+Below is the search procedure I followed to come up with that list.
+
+## Power supplies
+
+They are the first components to fail. We already have some problems with the
+monitoring of some power supplies. They will soon stop being manufactured, so we
+should increase out stack.
+
+Most Xeon nodes use the DELTA DPS-750XB A:
+
+    hut% sudo ipmitool fru
+    ...
+    FRU Device Description : Pwr Supply 1 FRU (ID 2)
+     Product Manufacturer  : DELTA
+     Product Name          : DPS-750XB A
+     Product Part Number   : E98791-010
+     Product Version       : 05
+     Product Serial        : XXXXXXXXXXXXXXXXX
+
+And we only have one per node. We should make the power supply redundant so we
+can tolerate it to fail without bringing down the node.
+
+They are available on Amazon, but they are very expensive (287.54 €):
+
+<https://www.amazon.es/DPS-750XB-E98791-010-alimentaci%C3%B3n-conmutada-Platinum/dp/B0DB65G4VT>
+
+On Aliexpress they are much cheaper (57.69 €):
+
+<https://es.aliexpress.com/item/1005004090017186.html>
+
+We have 11 nodes plus the login, but I'm not able to figure out which power
+supply the login is using.
+
+The login uses another one, AXX1100PCRPS, and only has one slot populated. We
+may want to also we another one, but I would need to reset the FRU and I don't
+have access to the login node. So I will leave this for Operations to deal with.
+We can live without the login if needed.
+
+## RAM DIMM
+
+The DIMM modules also experience errors, which are monitored by Linux. In some
+nodes we see non-recoverable errors that are no longer corrected by the ECC. We
+need to replace the bad modules.
+
+Having two spare modules per node would be enough to cover most problems in the
+future.
+
+> 16 GB, 2400 MHz RDIMM
+
+The module from dmidecode:
+
+    Handle 0x0026, DMI type 17, 40 bytes
+    Memory Device
+        Array Handle: 0x0020
+        Error Information Handle: Not Provided
+        Total Width: 72 bits
+        Data Width: 64 bits
+        Size: 16 GB
+        Form Factor: DIMM
+        Set: None
+        Locator: DIMM_B1
+        Bank Locator: NODE 1
+        Type: DDR4
+        Type Detail: Synchronous
+        Speed: 2400 MT/s
+        Manufacturer: Micron
+        Serial Number: XXXXXXXX
+        Asset Tag:
+        Part Number: 36ASF2G72PZ-2G3B1
+        Rank: 2
+        Configured Memory Speed: 2400 MT/s
+        Minimum Voltage: Unknown
+        Maximum Voltage: Unknown
+        Configured Voltage: Unknown
+
+Which is this module:
+
+<https://www.amazon.com/Micron-PC4-19200-DDR4-2400MHz-Registered-MTA36ASF2G72PZ-2G3B1/dp/B01KBCNEGI>
+
+But they have only one in stock. Here is more details:
+
+> 16GB PC4-19200 DDR4-2400MHz 
+
+The must have the following features:
+
+- 16 GB
+- DDR4
+- Speed at least 2400 MT/s
+- ECC
+- Registered
+- Best if from Micron
+
+I would say having 8 spare modules would be enough for now, as we only have a
+few that are currently failing. We could upgrade the modules later, as they
+don't have much risk of stopping being manufactured like the power supplies.
+
+These may work:
+
+- 1 x 16GB, 69,11€ <https://www.amazon.es/PC4-19200-REGISTRADO-SERVIDORES-Estaciones-CHIPKILL/dp/B06X42HC9N>
+
+- 2 x 16GB, 128,85€ <https://www.amazon.es/PC4-19200-REGISTERED-MEMORY-WORKSTATIONS-MOTHERBOARDS/dp/B06W9P3RKF>
+
+It is cheaper to buy them by pairs, so let's use the last one.
+
+## Screwdriver set
+
+In order to change and replace the machine parts we need a set of screwdrivers.
+Instead of having to bring my own from home, I want to have one at BSC. These
+are enough and come in a nice box so I don't lose them:
+
+<https://www.amazon.es/BLOSTM-Juego-Destornilladores-Profesionales-Destornillador/dp/B09W9R8J3S>
+
+## Serial port adaptor
+
+In order to debug problems with several components, we need to be able to plug
+to the serial port of the CPU. As we may deal with different voltages and
+pinouts, the most versatile option is to just be able to select the voltage and
+expose a pin interface.
+
+This one would do:
+
+<https://www.amazon.es/DSD-TECH-SH-U09C5-convertidor-Soporte/dp/B07WX2DSVB>
+
+## Storage for raccoon
+
+Given that we are currently using raccoon for builds too, we would need to
+increase its current storage. We only have available 270 GB, so we can benefit
+from another disk. Using 2 TiB would be plenty. This one seems enough:
+
+- 135,99€ <https://www.amazon.es/Crucial-BX500-pulgadas-interno-CT2000BX500SSD101/dp/B0CCN9QWKT>

m/hut/monitoring.nix

@@ -4,7 +4,6 @@
   imports = [
     ../module/slurm-exporter.nix
     ./gpfs-probe.nix
-    ./nix-daemon-exporter.nix
   ];
 
   age.secrets.grafanaJungleRobotPassword = {
@@ -109,7 +108,6 @@
             "127.0.0.1:${toString config.services.prometheus.exporters.smartctl.port}"
             "127.0.0.1:9341" # Slurm exporter
             "127.0.0.1:9966" # GPFS custom exporter
-            "127.0.0.1:9999" # Nix-daemon custom exporter
             "127.0.0.1:${toString config.services.prometheus.exporters.blackbox.port}"
           ];
         }];

m/hut/nix-daemon-builds.sh

@@ -1,26 +0,0 @@
-#!/bin/sh
-
-# Locate nix daemon pid
-nd=$(pgrep -o nix-daemon)
-
-# Locate children of nix-daemon
-pids1=$(tr ' ' '\n' < "/proc/$nd/task/$nd/children")
-
-# For each children, locate 2nd level children
-pids2=$(echo "$pids1" | xargs -I @ /bin/sh -c 'cat /proc/@/task/*/children' | tr ' ' '\n')
-
-cat <<EOF
-HTTP/1.1 200 OK
-Content-Type: text/plain; version=0.0.4; charset=utf-8; escaping=values
-
-# HELP nix_daemon_build Nix daemon derivation build state.
-# TYPE nix_daemon_build gauge
-EOF
-
-for pid in $pids2; do
-  name=$(cat /proc/$pid/environ 2>/dev/null | tr '\0' '\n' | rg "^name=(.+)" - --replace '$1')
-  user=$(ps -o uname= -p "$pid")
-  if [ -n "$name" -a -n "$user" ]; then
-    printf 'nix_daemon_build{user="%s",name="%s"} 1\n' "$user" "$name"
-  fi
-done

m/hut/nix-daemon-exporter.nix

@@ -1,23 +0,0 @@
-{ pkgs, config, lib, ... }:
-let
-  script = pkgs.runCommand "nix-daemon-exporter.sh" { }
-    ''
-      cp ${./nix-daemon-builds.sh} $out;
-      chmod +x $out
-    ''
-  ;
-in
-{
-  systemd.services.nix-daemon-exporter = {
-    description = "Daemon to export nix-daemon metrics";
-    path = [ pkgs.procps pkgs.ripgrep ];
-    wantedBy = [ "default.target" ];
-    serviceConfig = {
-      Type = "simple";
-      ExecStart = "${pkgs.socat}/bin/socat TCP4-LISTEN:9999,fork EXEC:${script}";
-      # Needed root to read the environment, potentially unsafe
-      User = "root";
-      Group = "root";
-    };
-  };
-}