Document how to monitor deadlocks in DBM (#26262)

* Document how to monitor deadlocks in DBM

* Reword a few things and remove the Notes section

* Fix broken link on deadlock XE buffer

* Add more information on what to expect from the deadlock tab

* Fix tense in guide title

* Fix grammar and punctuation on exploring deadlock events section

content/en/database_monitoring/guide/_index.md

@@ -19,6 +19,7 @@ cascade:
 
 {{< whatsnext desc="SQL Server guides:" >}}
     {{< nextlink href="database_monitoring/guide/sql_alwayson" >}}Exploring SQL Server AlwaysOn Availability Groups{{< /nextlink >}}
+    {{< nextlink href="database_monitoring/guide/sql_deadlock" >}}Configuring Deadlock Monitoring on SQL Server{{< /nextlink >}}
 {{< /whatsnext >}}
 
 {{< whatsnext desc="PostgreSQL guides:" >}}

content/en/database_monitoring/guide/sql_deadlock.md

@@ -0,0 +1,70 @@
+---
+title: Configuring Deadlock Monitoring on SQL Server
+further_reading:
+- link: "/database_monitoring/"
+  tag: "Documentation"
+  text: "Database Monitoring"
+- link: "/database_monitoring/setup_sql_server/"
+  tag: "Documentation"
+  text: "Setting Up SQL Server"
+- link: "/database_monitoring/troubleshooting/"
+  tag: "Documentation"
+  text: "Troubleshooting Database Monitoring"
+---
+
+The Deadlock view enables you to explore deadlock events in your SQL Server database.
+A deadlock occurs when two or more processes are unable to proceed because each is waiting for the other to release resources.
+This guide assumes that Database Monitoring has been configured for your [SQL Server][1].
+
+## Before you begin
+
+Supported databases
+: SQL Server
+
+Supported deployments
+: All deployment types except Azure DB (Azure Managed Instance is supported)
+
+Supported Agent versions
+: 7.59.0+
+
+## Setup
+1. In the SQL Server database instance, create a Datadog Extended Events (XE) session. You can run the session on any database in the instance.
+
+   **Note**: If the Datadog XE session isn't created in the database, the Agent still attempts to collect deadlock events from a default SQL Server XE view. This view writes to the buffer pool, but there's a higher chance of missing events because of a size limitation on the XML queried from it. For more information, see [You may not see the data you expect in Extended Event Ring Buffer Targets][2] on the SQL Server Support Blog.
+
+```sql
+  CREATE EVENT SESSION datadog
+  ON SERVER
+  ADD EVENT sqlserver.xml_deadlock_report
+  ADD TARGET package0.ring_buffer
+  WITH (
+      MAX_MEMORY = 1024 KB,
+      EVENT_RETENTION_MODE = ALLOW_SINGLE_EVENT_LOSS,
+      MAX_DISPATCH_LATENCY = 30 SECONDS,
+      STARTUP_STATE = ON
+  );
+  GO
+
+  ALTER EVENT SESSION datadog ON SERVER STATE = START;
+  GO
+```
+
+2. In the Datadog Agent, enable deadlocks in `sqlserver.d/conf.yaml`.
+```yaml
+  deadlocks_collection:
+      enabled: true
+```
+
+## Exploring deadlock events
+
+To access the deadlock view, navigate to the **APM** > **Database Monitoring** > **Databases** tab, select a SQL Server host, and then click the **Deadlocks** tab.
+The deadlock tab displays details about the victim and survivor processes, and includes a link to the deadlock diagram.
+
+**Note**: Because deadlocks occur infrequently, it's unlikely that any deadlock information will be visible right away.
+
+## Further reading
+
+{{< partial name="whats-next/whats-next.html" >}}
+
+[1]: /database_monitoring/setup_sql_server/
+[2]: https://techcommunity.microsoft.com/blog/sqlserversupport/you-may-not-see-the-data-you-expect-in-extended-event-ring-buffer-targets8230-/315838

content/en/database_monitoring/setup_sql_server/azure.md

@@ -8,8 +8,9 @@ further_reading:
 - link: "/database_monitoring/troubleshooting/?tab=sqlserver"
   tag: "Documentation"
   text: "Troubleshoot Common Issues"
-
-
+- link: "/database_monitoring/guide/sql_deadlock/"
+  tag: "Documentation"
+  text: "Configure Deadlock Monitoring"
 ---
 
 Database Monitoring provides deep visibility into your Microsoft SQL Server databases by exposing query metrics, query samples, explain plans, database states, failovers, and events.

content/en/database_monitoring/setup_sql_server/gcsql.md

@@ -5,8 +5,9 @@ further_reading:
 - link: "/integrations/sqlserver/"
   tag: "Documentation"
   text: "SQL Server Integration"
-
-
+- link: "/database_monitoring/guide/sql_deadlock/"
+  tag: "Documentation"
+  text: "Configure Deadlock Monitoring"
 ---
 
 Database Monitoring provides deep visibility into your Microsoft SQL Server databases by exposing query metrics, query samples, explain plans, database states, failovers, and events.

content/en/database_monitoring/setup_sql_server/rds.md

@@ -8,8 +8,9 @@ further_reading:
 - link: "/database_monitoring/troubleshooting/?tab=sqlserver"
   tag: "Documentation"
   text: "Troubleshoot Common Issues"
-
-
+- link: "/database_monitoring/guide/sql_deadlock/"
+  tag: "Documentation"
+  text: "Configure Deadlock Monitoring"
 ---
 
 Database Monitoring provides deep visibility into your Microsoft SQL Server databases by exposing query metrics, query samples, explain plans, database states, failovers, and events.

content/en/database_monitoring/setup_sql_server/selfhosted.md

@@ -8,6 +8,9 @@ further_reading:
 - link: "/database_monitoring/troubleshooting/?tab=sqlserver"
   tag: "Documentation"
   text: "Troubleshoot Common Issues"
+- link: "/database_monitoring/guide/sql_deadlock/"
+  tag: "Documentation"
+  text: "Configure Deadlock Monitoring"
 - link: "https://www.datadoghq.com/blog/migrate-sql-workloads-to-azure-with-datadog/"
   tag: "Blog"
   text: "Strategize your Azure migration for SQL workloads with Datadog"