From f69e545d6429aece0e55975c3b2426f20e91e545 Mon Sep 17 00:00:00 2001
From: Afonso Jorge Ramos <afonsojorgeramos@gmail.com>
Date: Sat, 20 Jun 2026 09:11:12 +0100
Subject: [PATCH] fix(truenas): report actual memory usage and pool free space
 (#6017)

---
 .../src/truenas/test/truenas-integration.spec.ts    | 13 ++++++++-----
 .../integrations/src/truenas/truenas-integration.ts | 11 ++++++++---
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/packages/integrations/src/truenas/test/truenas-integration.spec.ts b/packages/integrations/src/truenas/test/truenas-integration.spec.ts
index 28ff3b8d1..91ab0662c 100644
--- a/packages/integrations/src/truenas/test/truenas-integration.spec.ts
+++ b/packages/integrations/src/truenas/test/truenas-integration.spec.ts
@@ -132,8 +132,9 @@ const happyResponder = (method: string) => {
           aggregations: emptyAggregations(),
           start: 0,
           end: 1,
-          legend: [],
-          data: [[1000, 8_000_000_000]],
+          // The "memory" graph reports available (free) memory: legend is ["time", "available"].
+          legend: ["time", "available"],
+          data: [[1000, 6_000_000_000]],
         },
         {
           name: "cputemp",
@@ -194,15 +195,17 @@ describe("TrueNasIntegration", () => {
       version: "TrueNAS-SCALE-24.10",
       cpuModelName: "Intel Xeon",
       cpuTemp: 45,
-      memAvailableInBytes: 16_000_000_000,
-      memUsedInBytes: 8_000_000_000,
+      // physmem (16 GB) minus the reported available 6 GB leaves 10 GB used.
+      memAvailableInBytes: 6_000_000_000,
+      memUsedInBytes: 10_000_000_000,
       uptime: 3600,
       rebootRequired: false,
       availablePkgUpdates: 0,
       loadAverage: null,
       gpu: [],
       network: { up: 20_000, down: 10_000 },
-      fileSystem: [{ deviceName: "tank", available: "1000", used: "500", percentage: 50 }],
+      // `available` is the free space left on the pool (free = 500), not its total size.
+      fileSystem: [{ deviceName: "tank", available: "500", used: "500", percentage: 50 }],
       smart: [{ deviceName: "tank", healthy: true, overallStatus: "ONLINE", temperature: null }],
     });
   });
diff --git a/packages/integrations/src/truenas/truenas-integration.ts b/packages/integrations/src/truenas/truenas-integration.ts
index adbe32b3b..21f526201 100644
--- a/packages/integrations/src/truenas/truenas-integration.ts
+++ b/packages/integrations/src/truenas/truenas-integration.ts
@@ -37,14 +37,19 @@ export class TrueNasIntegration extends Integration implements ISystemHealthMoni
     const upload = this.extractNetworkTrafficData(netdata, 2); // Index 2 is "sent"
     const download = this.extractNetworkTrafficData(netdata, 1); // Index 1 is "received"
 
+    // The "memory" reporting graph reports available (free) memory, its legend is ["time", "available"].
+    // Used memory is therefore the physical total minus what is still available (clamped against timing skew).
+    const memAvailableInBytes = memoryData[1] ?? 0; // Index 0 is the UNIX timestamp, Index 1 is available bytes
+    const memUsedInBytes = Math.max(systemInformation.physmem - memAvailableInBytes, 0);
+
     return {
       cpuUtilization: cpuData.reduce((acc, item) => acc + (item > 100 ? 0 : item), 0) / cpuData.length,
       cpuTemp: Math.max(...cpuTempData.filter((_item, index) => index > 0)),
-      memAvailableInBytes: systemInformation.physmem,
-      memUsedInBytes: memoryData[1] ?? 0, // Index 0 is UNIX timestamp, Index 1 is free space in bytes
+      memAvailableInBytes,
+      memUsedInBytes,
       fileSystem: datasets.map((dataset) => ({
         deviceName: dataset.name,
-        available: `${dataset.size}`, // TODO: can we use number instead of string here?
+        available: `${dataset.free}`, // free space left on the pool
         used: `${dataset.allocated}`,
         percentage: (dataset.allocated / dataset.size) * 100,
       })),