Update monitor-event-hubs-reference.md

Updating event Hubs monitoring reference with Diagnostic Error logs

Author: Saglodha

articles/event-hubs/monitor-event-hubs-reference.md

@@ -179,6 +179,63 @@ Name | Description
 `OffsetCommit` | Number of offset commit calls made to the event hub 
 `OffsetFetch` | Number of offset fetch calls made to the event hub.
 
+## Diagnostic Error Logs
+Diagnostic error logs capture error messages for any client side, throttling and Quota exceeded errors. They provide detailed diagnostics for error identification.
+
+Diagnostic Error Logs include elements listed in below table:
+
+Name | Description | Supported in Azure Diagnostics | Supported in AZMSDiagnosticErrorLogs (Resource specific table)
+---|---|---|---|
+`ActivityId` | A randomly generated UUID that ensures uniqueness for the audit activity. | Yes | Yes
+`ActivityName` | Operation name  | Yes | Yes
+`NamespaceName` | Name of Namespace | Yes | yes
+`EntityType` | Type of Entity | Yes | Yes 
+`EntityName` | Name of Entity | Yes | Yes  
+`OperationResult` | Type of error in Operation (Clienterror or Serverbusy or quotaexceeded) | Yes | Yes
+`ErrorCount` | Count of identical errors during the aggregation period of 1 minute. | Yes | Yes 
+`ErrorMessage` | Detailed Error Message | Yes | Yes 
+`ResourceProvider` | Name of Service emitting the logs. Possible values: Microsoft.Eventhub and Microsoft.Servicebus | Yes | Yes 
+`Time Generated (UTC)` | Operation time | No | Yes
+`EventTimestamp` | Operation Time | Yes | No
+`Category` | Log category | Yes | No
+`Type`  | Type of Logs emitted | No | Yes
+
+Here's an example of Diagnostic error log entry:
+
+```json
+{
+    "ActivityId": "0000000000-0000-0000-0000-00000000000000",
+    "SubscriptionId": "<Azure Subscription Id",
+    "NamespaceName": "Name of Event Hubs Namespace",
+    "EntityType": "EventHub",
+    "EntityName": "Name of Event Hub",
+    "ActivityName": "SendMessage",
+    "ResourceId": "/SUBSCRIPTIONS/xxx/RESOURCEGROUPS/<Resource Group Name>/PROVIDERS/MICROSOFT.EVENTHUB/NAMESPACES/<Event hub namespace name>",,
+    "OperationResult": "ServerBusy",
+    "ErrorCount": 1,
+    "EventTimestamp": "3/27/2024 1:02:29.126 PM +00:00",
+    "ErrorMessage": "the request was terminated because the entity is being throttled by the application group with application group name <application group name> and policy name <throttling policy name>.error code: 50013.",
+    "category": "DiagnosticErrorLogs"
+ }
+
+```
+Resource specific table entry:
+```json
+{
+    "ActivityId": "0000000000-0000-0000-0000-00000000000000",
+    "NamespaceName": "Name of Event Hubs Namespace",
+    "EntityType": "Event Hub",
+    "EntityName": "Name of Event Hub",
+    "ActivityName": "SendMessage",
+    "ResourceId": "/SUBSCRIPTIONS/xxx/RESOURCEGROUPS/<Resource Group Name>/PROVIDERS/MICROSOFT.EVENTHUB/NAMESPACES/<Event hub namespace name>",,
+    "OperationResult": "ServerBusy",
+    "ErrorCount": 1,
+    "TimeGenerated [UTC]": "1/27/2024 4:02:29.126 PM +00:00",
+    "ErrorMessage": "The request was terminated because the entity is being throttled by the application group with application group name <application group name> and policy name <throttling policy name>.error code: 50013.",
+    "Type": "AZMSDiagnosticErrorLogs"
+ }
+
+```
 
 ## Azure Monitor Logs tables
 Azure Event Hubs uses Kusto tables from Azure Monitor Logs. You can query these tables with Log Analytics. For a list of Kusto tables the service uses, see [Azure Monitor Logs table reference](/azure/azure-monitor/reference/tables/tables-resourcetype#event-hubs).