RS: Check DB availability

content/operate/rs/databases/durability-ha/db-availability.md

@@ -0,0 +1,66 @@
+---
+alwaysopen: false
+categories:
+- docs
+- operate
+- rs
+db_type: database
+description: Verify if a Redis Software database is available to perform read and write operations and can respond to queries from client applications.
+linkTitle: Database availability
+title: Check database availability
+toc: 'true'
+weight: 30
+---
+
+You can use the [database availability API]({{<relref "/operate/rs/references/rest-api/requests/bdbs/availability">}}) to verify whether a Redis Software database is available to perform read and write operations and can respond to queries from client applications. Load balancers and automated monitoring tools can use this API to monitor database availability.
+
+## Check database availability for monitoring
+
+To monitor database availability, use the following REST API request:
+
+```sh
+GET /v1/bdbs/<database_id>/availability
+```
+
+If the OSS Cluster API is enabled, this request verifies all endpoints for this database are available. Otherwise, it verifies the database has at least one available endpoint.
+
+Returns the status code 200 OK if the database is available.
+
+If the database is unavailable, returns an error status code and a JSON object that contains [`error_code` and `description` fields]({{<relref "/operate/rs/references/rest-api/requests/bdbs/availability#get-db-error-codes">}}).
+
+## Check local database endpoint availability for load balancers
+
+To check database availability when using a load balancer and the recommended `all-nodes` proxy policy, use the local database endpoints for each node:
+
+```sh
+GET /v1/local/bdbs/<database_id>/endpoint/availability
+```
+
+Returns the status code 200 OK if the local database endpoint is available.
+
+If the local database endpoint is unavailable, returns an error status code and a JSON object that contains [`error_code` and `description` fields]({{<relref "/operate/rs/references/rest-api/requests/bdbs/availability#get-endpoint-error-codes">}}).
+
+## Availability by database status
+
+| Database status | Availability |
+|-----------------|--------------|
+| active          | <span title="Available">&#x2705;</span> Available |
+| active-change-pending | <span title="Available">&#x2705;</span> Available |
+| creation-failed | <span title="Not available">:x:</span> Not available |
+| delete-pending  | <span title="Availability not guaranteed" class="font-serif">:warning:</span> Availability not guaranteed |
+| import-pending  | <span title="Available">&#x2705;</span> Available |
+| pending         | <span title="Available">&#x2705;</span> Available |
+| recovery        | <span title="Not available">:x:</span> Not available |
+
+## Availability by shard status
+
+| Shard status | Availability |
+|--------------|--------------|
+| busy         | <span title="Available">&#x2705;</span> Available |
+| down         | <span title="Not available">:x:</span> Not available |
+| importing    | <span title="Available">&#x2705;</span> Available |
+| loading      | <span title="Available">&#x2705;</span> Available |
+| ok           | <span title="Available">&#x2705;</span> Available |
+| timeout      | ?            |
+| trimming     | <span title="Available">&#x2705;</span> Available |
+| unknown      | ?            |