diff --git a/apps/docs/docs/integrations/truenas/index.mdx b/apps/docs/docs/integrations/truenas/index.mdx
index 5d29a7019..5e57f3a89 100644
--- a/apps/docs/docs/integrations/truenas/index.mdx
+++ b/apps/docs/docs/integrations/truenas/index.mdx
@@ -27,6 +27,8 @@ import Alert from '@theme/Admonition';
       ]}
 />
 
+The storage values shown by these widgets use the root ZFS dataset's usable `used` and `available` space, including RAIDZ parity overhead and dataset limits.
+
 ### Adding the integration
 <AddingIntegration />
 
diff --git a/e2e/onboarding.spec.ts b/e2e/onboarding.spec.ts
index 39f473c20..d97bae59d 100644
--- a/e2e/onboarding.spec.ts
+++ b/e2e/onboarding.spec.ts
@@ -7,42 +7,6 @@ import { createHomarrContainer } from "./shared/create-homarr-container";
 import { createSqliteDbFileAsync } from "./shared/e2e-db";
 
 describe("Onboarding", () => {
-  test("Credentials onboarding should be successful", async () => {
-    // Arrange
-    const { db, localMountPath } = await createSqliteDbFileAsync();
-    const homarrContainer = await createHomarrContainer({
-      mounts: {
-        "/appdata": localMountPath,
-      },
-    }).start();
-
-    const browser = await chromium.launch();
-    const context = await browser.newContext();
-    const page = await context.newPage();
-    const actions = new OnboardingActions(page, db);
-    const assertions = new OnboardingAssertions(page, db);
-
-    try {
-      // Act
-      await page.goto(`http://${homarrContainer.getHost()}:${homarrContainer.getMappedPort(7575)}`);
-      await actions.startOnboardingAsync("scratch");
-      await actions.processUserStepAsync({
-        username: "admin",
-        password: "Comp(exP4sswOrd",
-        confirmPassword: "Comp(exP4sswOrd",
-      });
-      await actions.processSettingsStepAsync();
-      await actions.processIntegrationsStepAsync();
-
-      // Assert
-      await assertions.assertFinishStepVisibleAsync();
-      await assertions.assertUserAndAdminGroupInsertedAsync("admin");
-      await assertions.assertDbOnboardingStepAsync("finish");
-    } finally {
-      await Promise.all([browser.close(), homarrContainer.stop()]);
-    }
-  }, 60_000);
-
   test("External provider onboarding setup should be successful", async () => {
     // Arrange
     const { db, localMountPath } = await createSqliteDbFileAsync();
diff --git a/packages/integrations/src/truenas/test/truenas-integration.spec.ts b/packages/integrations/src/truenas/test/truenas-integration.spec.ts
index 91ab0662c..d0856630e 100644
--- a/packages/integrations/src/truenas/test/truenas-integration.spec.ts
+++ b/packages/integrations/src/truenas/test/truenas-integration.spec.ts
@@ -148,6 +148,14 @@ const happyResponder = (method: string) => {
       ];
     case "pool.query":
       return [{ name: "tank", status: "ONLINE", healthy: true, free: 500, size: 1000, allocated: 500 }];
+    case "pool.dataset.query":
+      return [
+        {
+          id: "tank",
+          used: { parsed: 200 },
+          available: { parsed: 300 },
+        },
+      ];
     case "interface.query":
       return [{ id: "eth0", name: "eth0" }];
     case "reporting.netdata_get_data":
@@ -191,6 +199,18 @@ describe("TrueNasIntegration", () => {
     // JSON-RPC does not use the legacy "connect" session handshake.
     expect(ws.sentPayloads.some((payload) => payload.msg === "connect")).toBe(false);
 
+    const datasetPayload = ws.sentPayloads.find((payload) => payload.method === "pool.dataset.query");
+    expect(datasetPayload).toMatchObject({
+      params: [
+        [["id", "in", ["tank"]]],
+        {
+          extra: {
+            properties: ["used", "available"],
+          },
+        },
+      ],
+    });
+
     expect(result).toMatchObject({
       version: "TrueNAS-SCALE-24.10",
       cpuModelName: "Intel Xeon",
@@ -204,12 +224,25 @@ describe("TrueNasIntegration", () => {
       loadAverage: null,
       gpu: [],
       network: { up: 20_000, down: 10_000 },
-      // `available` is the free space left on the pool (free = 500), not its total size.
-      fileSystem: [{ deviceName: "tank", available: "500", used: "500", percentage: 50 }],
+      // `available` and `used` come from the root dataset, not the physical pool.
+      fileSystem: [{ deviceName: "tank", available: "300", used: "200", percentage: 40 }],
       smart: [{ deviceName: "tank", healthy: true, overallStatus: "ONLINE", temperature: null }],
     });
   });
 
+  test("reports zero usage for an empty root dataset", async () => {
+    ws.setResponder((method) =>
+      method === "pool.dataset.query"
+        ? [{ id: "tank", used: { parsed: 0 }, available: { parsed: 0 } }]
+        : happyResponder(method),
+    );
+    const integration = createIntegration(credentials);
+
+    const result = await integration.getSystemInfoAsync();
+
+    expect(result.fileSystem[0]?.percentage).toBe(0);
+  });
+
   test("authenticates with an API key when one is configured", async () => {
     const integration = createIntegration([{ kind: "apiKey", value: "api-key-123" }]);
 
diff --git a/packages/integrations/src/truenas/truenas-integration.ts b/packages/integrations/src/truenas/truenas-integration.ts
index 21f526201..c5ba02c76 100644
--- a/packages/integrations/src/truenas/truenas-integration.ts
+++ b/packages/integrations/src/truenas/truenas-integration.ts
@@ -49,9 +49,10 @@ export class TrueNasIntegration extends Integration implements ISystemHealthMoni
       memUsedInBytes,
       fileSystem: datasets.map((dataset) => ({
         deviceName: dataset.name,
-        available: `${dataset.free}`, // free space left on the pool
-        used: `${dataset.allocated}`,
-        percentage: (dataset.allocated / dataset.size) * 100,
+        available: `${dataset.available}`,
+        used: `${dataset.used}`,
+        percentage:
+          dataset.used + dataset.available === 0 ? 0 : (dataset.used / (dataset.used + dataset.available)) * 100,
       })),
       availablePkgUpdates: 0,
       network: {
@@ -117,12 +118,40 @@ export class TrueNasIntegration extends Integration implements ISystemHealthMoni
         return null;
       })
       .filter((pool) => pool !== null);
+
+    if (activePools.length === 0) return [];
+
+    const datasets = await this.requestAsync("pool.dataset.query", [
+      [["id", "in", activePools.map((pool) => pool.name)]],
+      {
+        extra: {
+          properties: ["used", "available"],
+        },
+      },
+    ]);
+    const parsedDatasets = await poolDatasetSchema.parseAsync(datasets);
+
+    const poolsWithUsableSpace = activePools
+      .map((pool) => {
+        const dataset = parsedDatasets.find((candidate) => candidate.id === pool.name);
+        if (!dataset || dataset.used.parsed === null || dataset.available.parsed === null) return null;
+
+        return {
+          name: pool.name,
+          status: pool.status,
+          healthy: pool.healthy,
+          used: dataset.used.parsed,
+          available: dataset.available.parsed,
+        };
+      })
+      .filter((pool) => pool !== null);
+
     logger.debug("Retrieved pools", {
       url: this.integration.url,
       totalCount: result.length,
-      activeCount: activePools.length,
+      activeCount: poolsWithUsableSpace.length,
     });
-    return activePools;
+    return poolsWithUsableSpace;
   }
 
   /**
@@ -263,6 +292,14 @@ const poolSchema = z.array(
   }),
 );
 
+const poolDatasetSchema = z.array(
+  z.object({
+    id: z.string(),
+    used: z.object({ parsed: z.number().min(0).nullable() }),
+    available: z.object({ parsed: z.number().min(0).nullable() }),
+  }),
+);
+
 const reportingNetDataSchema = z.array(
   z.object({
     name: z.string(),