canonical · sed-i · Feb 4, 2026 · Feb 5, 2026 · Feb 5, 2026 · lucabello
diff --git a/docs/how-to/upgrade.md b/docs/how-to/upgrade.md
@@ -1,5 +1,17 @@
 # Upgrade instructions
 
+## COS 3
+
+### Migrate from COS 2 to COS 3
+
+
+### Migrate from COS Lite 2 to COS 3
+
+
+### Migrate from COS Lite 2 to COS Lite 3
+
+
+
 ## COS 2
 
 ### Migrate from COS Lite 1 to COS 2

diff --git a/docs/reference/release-notes.md b/docs/reference/release-notes.md
@@ -1,41 +1,47 @@
-# COS 2 release notes
-October 2025
+# COS 3 release notes
+May 2026
 
-These release notes cover new features and changes in COS 2.
+These release notes cover new features and changes in COS 3.
 
-COS 2 is designated as a short-term support release. This means it will continue to receive security updates and critical bug fixes for 9 months.
+COS 3 is designated as a long-term support (LTS) release. This means it will continue to receive security updates and critical bug fixes for 10 years.
 
 See our [release policy](release-policy.md) and [upgrade instructions](../how-to/upgrade.md).
 
 ## Requirements and compatibility
 See [system requirements](system-requirements.md).
 
-COS 2 is compatible with Juju v3.6+. When deployed using terraform, Juju v3.6.11+ is recommended.
+COS 3 is compatible with Juju v3.6+.
+
+
+## What's new in COS 3
+
+
+### COS components
+
+| Component                | Version | Upstream context |
+|--------------------------|---------|------------------|
+| alertmanager             | 0.x     |                  |
+| catalogue                |         |                  |
+| grafana                  | 12.x    |                  |
+| loki                     | 3.x     |                  |
+| mimir                    | 3.x     |                  |
+| opentelemetry-collector  | 0.x     |                  |
+| s3-integrator            |         |                  |
+| self-signed-certificates |         |                  |
+| tempo                    | 2.x     |                  |
+| traefik                  | 2.x     |                  |
+
+
+### COS Lite components
+
+
 
-## What's new in COS 2
 
-- Terraform modules for [COS](https://github.com/canonical/observability-stack/tree/main/terraform/cos)
-  and [COS Lite](https://github.com/canonical/observability-stack/tree/main/terraform/cos-lite).
-  As Juju bundles are deprecated, the standard way of deploying COS is now using the
-  [Juju Terraform provider](https://registry.terraform.io/providers/juju/juju/latest/docs).
-  - [Telemetry correlation](../explanation/telemetry-correlation.md) is now automatically enabled when you deploy COS using the
-    Terraform module.
-- **Grafana v12**. We upgraded the workload version from Grafana 9 to Grafana 12. A thorough review of Grafana's breaking changes and how they affect us is available [on Discourse](https://discourse.charmhub.io/t/cos-will-start-using-grafana-12-what-changed/18868).
-- **Opentelemetry collector**. Charmed opentelemetry-collector was released. The charm was designed to be a drop-in replacement for 
-  the grafana-agent charm (upstream grafana-agent is EOL since November 2025, and we will support charmed grafana-agent until July 2026).
-- `extra_alert_labels` config option. A new config option in grafana-agent and opentelemetry-collector enabled adding custom labels to alert rules. Custom labels are useful for differentiating alerts coming from sites with different SLAs.
-- **API links in catalogue-k8s**. The cards in catalogue-k8s now support extra links for documentation and APIs. COS charms now provide links to the workload API, making it easier to locate ingress URLs
-for workloads without a web UI.
 
 ## Notable changes in peripheral charms
-- Multiple scripts in script-exporter. The script exporter VM charm can now take an archive of scripts. It can now be deployed on 20.04, 22.04 and 24.04.
-- Prior to cos-proxy `rev166`, duplicate telemetry exists after `upgrade` and `config-changed` hooks. Follow [these remediation steps](https://github.com/canonical/cos-proxy-operator/issues/208#issuecomment-3367094739) to resolve, requiring you to upgrade cos-proxy to `>=rev166` via `track2`. This also includes the feature of scrape-configs and alert rules for `cos-agent` relations.
+
 
 ## Backwards-incompatible changes
-- Charms from track 2 can be deployed on juju models v3.6+.
-- Terraform module variable `model_name` renamed to `model` in all charms.
-- Grafana v12 changes how the panel view URL is generated for repeated panels. Links to **repeated panels** in a dashboard changed slightly; previously bookmarked links to a repeated panel (not its dashboard) will no longer work.
 
 
 ## Deprecated features
-- The `LogProxyConsumer` charm library (owned by Loki) is deprecated. Use Pebble log forwarding instead.
diff --git a/docs/reference/release-policy.md b/docs/reference/release-policy.md
@@ -4,6 +4,15 @@ Our release policy includes two kinds of releases, short-term releases and long-
 
 We release every six months, same as Ubuntu, and our LTS releases coincide with [Ubuntu's LTS release cadence](https://ubuntu.com/about/release-cycle).
 
+
+## Long-term support
+
+| Track   | Release date  | End of life       | Ubuntu base                          | Min. Juju version |
+| ------- | ------------- | ----------------- | ------------------------------------ | ----------------- |
+| `3-lts` | 2026-05       | 2036-04 (approx.) | 26.04 (rocks), 22.04+ (subordinates) | 3.6               |
+
+
+
 ## Short-term releases
 Short-term releases are supported for nine months by providing security patches and critical bug fixes.
 
@@ -13,13 +22,6 @@ Short-term releases are supported for nine months by providing security patches
 | `1`   | 2025-05      | 2026-02     | 24.04 (rocks)                        | 3.1               | Mimir 2.x, Prometheus 2.x, Loki 2.x (COS Lite), Loki 3.0 (COS), Grafana 9.x, Grafana Agent 0.40.4         |
 
 
-## Long-term support
-
-| Track   | Release date        | End of life         | Ubuntu base                          | Min. Juju version | Brief summary |
-| ------- | ------------------- | ------------------- | ------------------------------------ | ----------------- | ------------- |
-| `3-lts` | 2026-04 (predicted) | 2038-04 (predicted) | 26.04 (rocks), 22.04+ (subordinates) |                   |               |
-
-
 ## Charmhub tracks and git branches
 We create the Charmhub track at beginning of a cycle, and a git branch at end of cycle.
 For example, during June-September 2025, we had track `2` on Charmhub, but only `track/1` and `main` branches on github.
diff --git a/docs/reference/system-requirements.md b/docs/reference/system-requirements.md
@@ -1,7 +1,28 @@
 # System requirements
 
 ## COS
-3 nodes of 8cpu16gb or better.
+3 nodes of 8cpu16gb or better. At least 100 GB disk space.
+
 
 ## COS Lite
-4cpu8gb or better.
+As a general rule, plan for a 4cpu8gb or better VM.
+
+If you have an [estimate for the expected telemetry rate](../how-to/evaluate-telemetry-volume.md), refer to the tables below.
+
+
+### Metrics (Prometheus)
+
+| Metrics/min | vCPUs | Mem (GB) | Disk (GiB/day) |
+|-------------|-------|----------|----------------|
+|     1 M     |   2   |     6    |        6       |
+|     3 M     |   3   |     9    |       14       |
+|     6 M     |   3   |    14    |       27       |
+
+
+### Logs (Loki)
+
+| Logs/min | vCPUs | Mem (GB) | Disk (GiB/day) |
+|----------|-------|----------|----------------|
+|   60 k   |   5   |     8    |       20       |
+|   180 k  |   5   |     8    |       60       |
+|   360 k  |   6   |     8    |       120      |