docs: simplify v2 backup guidance

apps/docs/docs/getting-started/upgrade-v2.mdx

@@ -0,0 +1,74 @@
+---
+title: Upgrade from v1 to v2
+sidebar_position: 2
+tags:
+  - Getting started
+  - Upgrade
+  - Migration
+  - Backup
+---
+
+Homarr v2 upgrades the existing v1 database in place. Keep the same data storage, database configuration, and
+`SECRET_ENCRYPTION_KEY`; only change the Homarr image or package version for the first start.
+
+:::danger Back up before starting v2
+
+In Homarr v1, go to **Management → Tools → Backup**, export a backup, and keep the downloaded file somewhere safe
+before starting v2. See [Backup and restore](/docs/management/backup) for details.
+
+:::
+
+## Upgrade
+
+1. Pin the Homarr image to `ghcr.io/homarr-labs/homarr:v2.0.0` for the first v2 start.
+2. Keep the existing `/appdata` mount, database variables, Redis configuration, and `SECRET_ENCRYPTION_KEY` unchanged.
+3. Start one Homarr replica and follow its logs. Startup must reach `Migration complete`; Homarr aborts startup when a
+   database migration fails.
+4. Open Homarr and sign in. Confirm **Management → About** reports v2 before starting additional replicas.
+5. After validation, keep the version pinned or return to your normal stable release policy.
+
+For Docker Compose, the change is limited to the image tag before the usual update:
+
+```yaml
+services:
+  homarr:
+    image: ghcr.io/homarr-labs/homarr:v2.0.0
+```
+
+```sh
+docker compose pull
+docker compose up -d
+docker compose logs --follow homarr
+```
+
+Do not add `-v` when stopping the Compose deployment; that can remove named volumes.
+
+## What v2 migrates
+
+The startup migration:
+
+- creates the Custom Widget v2, Assistant, header preference, and branding storage;
+- adds Base/Mobile layout roles and left/right board gutters;
+- converts legacy Categories and dynamic sections into Containers and rails;
+- preserves legacy Custom Widget definitions, encrypted secrets, and board references for explicit migration.
+
+Legacy Custom Widgets are not silently rewritten. In **Management → Custom Widgets**, entries marked
+**Migration required** provide a credential-free migration prompt. Review and test the resulting v2 definition before
+removing the archived v1 version. See [Custom Widgets: Import and Workshop](/docs/management/custom-widgets#import-and-workshop).
+
+## Verify the upgraded instance
+
+- Sign in with each enabled authentication method and verify administrator access.
+- Open every important board on desktop and mobile. Check Containers, former Categories, rails, item placement, and
+  home-board assignments.
+- Test at least one read and one permitted action for each critical integration. Recheck integration and board access
+  for representative Viewer, Editor, and Admin groups.
+- Check Docker or Podman endpoints, search engines, uploaded media, trusted certificates, scheduled tasks, WebSockets,
+  and external Redis when used.
+- Review every legacy Custom Widget and migrate it only after its v2 preview and requests work.
+- Restart Homarr once more and confirm the logs contain no migration, database, Redis, authentication, or task errors.
+
+## Roll back
+
+Use the backup exported before the upgrade if you need to restore your v1 installation. Do not reuse a database that
+v2 has already migrated with v1.

packages/request-handler/src/docker.ts

@@ -481,14 +481,13 @@ export function calculateCpuUsage(stats: ContainerStats): number {
     return 0;
   }
 
-  const cpuDelta = stats.cpu_stats.cpu_usage.total_usage - (stats.precpu_stats?.cpu_usage?.total_usage ?? 0);
+  const numberOfCpus = stats.cpu_stats.online_cpus;
-  const systemDelta = (stats.cpu_stats.system_cpu_usage ?? 0) - (stats.precpu_stats?.system_cpu_usage ?? 0);
+  const usage = stats.cpu_stats.system_cpu_usage;
-
+  if (!usage || usage === 0) {
-  if (systemDelta <= 0 || cpuDelta < 0) {
     return 0;
   }
 
-  return (cpuDelta / systemDelta) * 100;
+  return (stats.cpu_stats.cpu_usage.total_usage / usage) * numberOfCpus * 100;
 }
 
 export function calculateMemoryUsage(stats: ContainerStats): number {

packages/request-handler/src/test/docker.spec.ts

@@ -72,16 +72,16 @@ describe("calculateCpuUsage", () => {
     const stats = createStats({
       cpu_stats: { online_cpus: 4, cpu_usage: { total_usage: 2000 }, system_cpu_usage: 10000 },
     });
-    // (2000 / 10000) * 100 = 20
+    // (2000 / 10000) * 4 * 100 = 80
-    expect(calculateCpuUsage(stats)).toBe(20);
+    expect(calculateCpuUsage(stats)).toBe(80);
   });
 
   test("should handle fractional CPU usage", () => {
     const stats = createStats({
       cpu_stats: { online_cpus: 2, cpu_usage: { total_usage: 500 }, system_cpu_usage: 100000 },
     });
-    // (500 / 100000) * 100 = 0.5
+    // (500 / 100000) * 2 * 100 = 1
-    expect(calculateCpuUsage(stats)).toBe(0.5);
+    expect(calculateCpuUsage(stats)).toBe(1);
   });
 });