Merge pull request #267203 from EdB-MSFT/pormetheus-case-sensitivity

updated case sesnitivity statements

Author: v-ccolin

articles/azure-monitor/essentials/prometheus-metrics-overview.md

@@ -5,7 +5,7 @@ author: EdB-MSFT
 ms.service: azure-monitor
 ms-author: edbaynash
 ms.topic: conceptual
-ms.date: 05/10/2023
+ms.date: 01/25/2024
 ---
 
 # Azure Monitor managed service for Prometheus
@@ -45,13 +45,14 @@ See [Azure Monitor service limits](../service-limits.md#prometheus-metrics) for
 ## Limitations/Known issues - Azure Monitor managed Service for Prometheus
 
 - Scraping and storing metrics at frequencies less than 1 second isn't supported.
-- Metrics with the same label names but different cases are rejected during ingestion (ex;- `diskSize(cluster="eastus", node="node1", filesystem="usr_mnt", FileSystem="usr_opt")` is invalid due to `filesystem` and `FileSystem` labels, and are rejected).
 - Microsoft Azure operated by 21Vianet cloud and Air gapped clouds aren't supported for Azure Monitor managed service for Prometheus.
 - To monitor Windows nodes & pods in your cluster(s), follow steps outlined [here](../containers/kubernetes-monitoring-enable.md#enable-windows-metrics-collection-preview).
 - Azure Managed Grafana isn't currently available in the Azure US Government cloud.
 - Usage metrics (metrics under `Metrics` menu for the Azure Monitor workspace) - Ingestion quota limits and current usage for any Azure monitor Workspace aren't available yet in US Government cloud.
 - During node updates, you might experience gaps lasting 1 to 2 minutes in some metric collections from our cluster level collector. This gap is due to a regular action from Azure Kubernetes Service to update the nodes in your cluster. This behavior is expected and occurs due to the node it runs on being updated. None of our recommended alert rules are affected by this behavior. 
 
+[!INCLUDE [case sensitivity](../includes/prometheus-case-sensitivity.md)] 
+
 ## Prometheus references
 Following are links to Prometheus documentation.
 
@@ -88,4 +89,4 @@ If you use the Azure portal to enable Prometheus metrics collection and install
 
 - [Enable Azure Monitor managed service for Prometheus on your Kubernetes clusters](../containers/kubernetes-monitoring-enable.md).
 - [Configure Prometheus alerting and recording rules groups](prometheus-rule-groups.md).
-- [Customize scraping of Prometheus metrics](prometheus-metrics-scrape-configuration.md).
+- [Customize scraping of Prometheus metrics](prometheus-metrics-scrape-configuration.md).

articles/azure-monitor/includes/prometheus-case-sensitivity.md

@@ -1,13 +1,16 @@
 ---
 ms.service: azure-monitor
 ms.topic: include
-ms.date: 04/01/2023
+ms.date: 01/25/2024
 ms.author: edbaynash
 author: EdB-MSFT
 ---
 
 ## Case sensitivity
-Azure managed Prometheus is a case insensitive system. If one time series differs from another only by a difference in the case of a string (metric name, label name, label value, etc), it's treated as the same time series. This behavior is different from native open source Prometheus, which is a case sensitive system.
+Azure managed Prometheus is a case insensitive system. It treats strings, such as metric names, label names, or label values, as the same time series if they differ from another time series only by the case of the string.
+
+> [!NOTE]
+> This behavior is different from native open source Prometheus, which is a case sensitive system.
 
 In Azure managed Prometheus the following time series are considered the same: 
 
@@ -16,10 +19,10 @@ In Azure managed Prometheus the following time series are considered the same:
 
 The above examples are a single time series in a time series database.
 -	Any samples ingested against them are stored as if they're scraped/ingested against a single time series.
--	If the examples above are ingested with the same timestamp, one of them is randomly dropped.
+-	If the preceding examples are ingested with the same timestamp, one of them is randomly dropped.
 -	The casing that's stored in the time series database and returned by a query is unpredictable. Different casing may be returned at different times for the same time series.
 -	Any metric name or label name/value matcher present in the query is retrieved from time series database by making a case-insensitive comparison. If there's a case sensitive matcher in a query, it's automatically treated as a case-insensitive matcher when making string comparisons.
 
-It is best practice to ensure that a time series is produced or scraped using a single consistent case.
+It's best practice to ensure that a time series is produced or scraped using a single consistent case.
 
-In OSS Prometheus, the above time series are treated as two different time series. Any samples scraped/ingested against them are stored separately.
+In Open Source Prometheus, the above time series are treated as two different time series. Any samples scraped/ingested against them are stored separately.

articles/azure-monitor/includes/prometheus-faq-i-am-missing-metrics-with-same-name-different-casing.md

@@ -8,4 +8,4 @@ author: EdB-MSFT
 
 ### Why am I missing metrics that have two labels with the same name but different casing?
 
-Metrics that have two label names that are the same except for their casing will be treated as having duplicate label names. These time series will be dropped upon ingestion since the two labels are seen as the same. For example, the time series `my_metric{ExampleLabel="label_value_0", examplelabel="label_value_1}` will be dropped due to duplicate labels since `ExampleLabel` and `examplelabel` will be seen as the same label name.
+Azure managed Prometheus is a case insensitive system. It treats strings, such as metric names, label names, or label values, as the same time series if they differ from another time series only by the case of the string. For more information, see [Prometheus metrics overview](/azure/azure-monitor/essentials/prometheus-metrics-overview#case-sensitivity).

includes/azure-monitor-limits-metrics.md

@@ -12,6 +12,8 @@ ms.custom: "include file"
 
 ### Ingestion
 
+Azure managed Prometheus is a case insensitive system. It treats strings, such as metric names, label names, or label values, as the same time series if they differ from another time series only by the case of the string. For more information, see [Prometheus metrics overview](/azure/azure-monitor/essentials/prometheus-metrics-overview#case-sensitivity). 
+ 
 The following limits apply to the Azure Monitor workspace ingesting your Prometheus metrics.
 
 | Limit | Value |