diff --git a/src/k8s-extension/HISTORY.rst b/src/k8s-extension/HISTORY.rst
index 09a13348d04..94df11be9ce 100644
--- a/src/k8s-extension/HISTORY.rst
+++ b/src/k8s-extension/HISTORY.rst
@@ -3,6 +3,10 @@
 Release History
 ===============
 
+1.6.6
+++++++++
+* microsoft.azuremonitor.containers: Extend ContainerInsights Extension for high log scale mode support.
+
 1.6.5
 ++++++++++++++++++
 * microsoft.dataprotection.kubernetes: Add support for 'DisableInformerCache' configuration.
diff --git a/src/k8s-extension/azext_k8s_extension/partner_extensions/ContainerInsights.py b/src/k8s-extension/azext_k8s_extension/partner_extensions/ContainerInsights.py
index b059850d7b4..5cf74793808 100644
--- a/src/k8s-extension/azext_k8s_extension/partner_extensions/ContainerInsights.py
+++ b/src/k8s-extension/azext_k8s_extension/partner_extensions/ContainerInsights.py
@@ -33,6 +33,21 @@
 logger = get_logger(__name__)
 DCR_API_VERSION = "2022-06-01"
 
+ContainerInsightsStreams = [
+    "Microsoft-ContainerLog",
+    "Microsoft-ContainerLogV2-HighScale",
+    "Microsoft-KubeEvents",
+    "Microsoft-KubePodInventory",
+    "Microsoft-KubeNodeInventory",
+    "Microsoft-KubePVInventory",
+    "Microsoft-KubeServices",
+    "Microsoft-KubeMonAgentEvents",
+    "Microsoft-InsightsMetrics",
+    "Microsoft-ContainerInventory",
+    "Microsoft-ContainerNodeInventory",
+    "Microsoft-Perf",
+]
+
 
 class ContainerInsights(DefaultExtension):
     def Create(self, cmd, client, resource_group_name, cluster_name, name, cluster_type, cluster_rp,
@@ -83,6 +98,7 @@ def Delete(self, cmd, client, resource_group_name, cluster_name, name, cluster_t
         # Delete DCR-A if it exists incase of MSI Auth
         useAADAuth = False
         isDCRAExists = False
+        enable_high_log_scale_mode = False
         cluster_rp, _ = get_cluster_rp_api_version(cluster_type=cluster_type, cluster_rp=cluster_rp)
         try:
             extension = client.get(resource_group_name, cluster_rp, cluster_type, cluster_name, name)
@@ -95,6 +111,7 @@ def Delete(self, cmd, client, resource_group_name, cluster_name, name, cluster_t
                 return
 
         subscription_id = get_subscription_id(cmd.cli_ctx)
+        resources = cf_resources(cmd.cli_ctx, subscription_id)
         # handle cluster type here
         cluster_resource_id = '/subscriptions/{0}/resourceGroups/{1}/providers/{2}/{3}/{4}'.format(subscription_id, resource_group_name, cluster_rp, cluster_type, cluster_name)
         if (extension is not None) and (extension.configuration_settings is not None):
@@ -108,6 +125,14 @@ def Delete(self, cmd, client, resource_group_name, cluster_name, name, cluster_t
                 useAADAuthSetting = configSettings['amalogs.useAADAuth']
                 if (isinstance(useAADAuthSetting, str) and str(useAADAuthSetting).lower() == "true") or (isinstance(useAADAuthSetting, bool) and useAADAuthSetting):
                     useAADAuth = True
+            
+            # Check if high log scale mode was enabled
+            if useAADAuth and 'amalogs.enableHighLogScaleMode' in configSettings:
+                highLogScaleSetting = configSettings['amalogs.enableHighLogScaleMode']
+                if isinstance(highLogScaleSetting, str):
+                    enable_high_log_scale_mode = (highLogScaleSetting.lower() == "true")
+                elif isinstance(highLogScaleSetting, bool):
+                    enable_high_log_scale_mode = highLogScaleSetting
         if useAADAuth:
             association_url = cmd.cli_ctx.cloud.endpoints.resource_manager + f"{cluster_resource_id}/providers/Microsoft.Insights/dataCollectionRuleAssociations/ContainerInsightsExtension?api-version={DCR_API_VERSION}"
             for _ in range(3):
@@ -131,6 +156,28 @@ def Delete(self, cmd, client, resource_group_name, cluster_name, name, cluster_t
                 except Exception:
                     pass  # its OK to ignore the exception since MSI auth in preview
 
+        if useAADAuth:
+            resource = resources.get_by_id(cluster_resource_id, '2020-01-01-preview')
+            cluster_location = resource.location.lower()
+            dcr_name = f"MSCI-{cluster_location}-{cluster_name}"
+            dcr_name = dcr_name[0:64]
+            
+            dcr_resource_id = f"/subscriptions/{subscription_id}/resourceGroups/{resource_group_name}/providers/Microsoft.Insights/dataCollectionRules/{dcr_name}"
+            dcr_url = cmd.cli_ctx.cloud.endpoints.resource_manager + f"{dcr_resource_id}?api-version={DCR_API_VERSION}"
+            response = send_raw_request(cmd.cli_ctx, "GET", dcr_url)
+            dcr_config = json.loads(response.text)
+            # Delete the DCR
+            for _ in range(3):
+                try:
+                    send_raw_request(cmd.cli_ctx, "DELETE", dcr_url,)
+                    logger.info(f"Successfully deleted DCR: {dcr_name}")
+                    break
+                except Exception as ex:
+                    logger.warning(f"Error deleting DCR: {str(ex)}")
+                    pass
+
+            if enable_high_log_scale_mode:
+                _delete_dce_for_dcr(cmd, subscription_id, resource_group_name, dcr_config)
 
 # Custom Validation Logic for Container Insights
 
@@ -464,6 +511,7 @@ def _get_container_insights_settings(cmd, cluster_resource_group_name, cluster_r
     subscription_id = get_subscription_id(cmd.cli_ctx)
     workspace_resource_id = ''
     useAADAuth = True
+    enableHighLogScaleMode = False  # Default value
     if 'amalogs.useAADAuth' not in configuration_settings:
         configuration_settings['amalogs.useAADAuth'] = "true"
     extensionSettings = {}
@@ -520,6 +568,16 @@ def _get_container_insights_settings(cmd, cluster_resource_group_name, cluster_r
                     raise InvalidArgumentValueError('streams must be an array type')
             extensionSettings["dataCollectionSettings"] = dataCollectionSettings
 
+        if useAADAuth and 'amalogs.enableHighLogScaleMode' in configuration_settings:
+            enableHighLogScaleMode = configuration_settings['amalogs.enableHighLogScaleMode']
+            if isinstance(enableHighLogScaleMode, str):
+                enableHighLogScaleMode_str = enableHighLogScaleMode.lower()
+                if enableHighLogScaleMode_str not in ["true", "false"]:
+                    raise InvalidArgumentValueError('amalogs.enableHighLogScaleMode value MUST be either true or false')
+                enableHighLogScaleMode = (enableHighLogScaleMode_str == "true")
+            elif not isinstance(enableHighLogScaleMode, bool):
+                raise InvalidArgumentValueError('amalogs.enableHighLogScaleMode value MUST be either true or false')
+
     workspace_resource_id = workspace_resource_id.strip()
 
     if configuration_protected_settings is not None:
@@ -548,7 +606,7 @@ def _get_container_insights_settings(cmd, cluster_resource_group_name, cluster_r
     if is_ci_extension_type:
         if useAADAuth:
             logger.info("creating data collection rule and association")
-            _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_resource_group_name, cluster_rp, cluster_type, cluster_name, workspace_resource_id, extensionSettings)
+            _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_resource_group_name, cluster_rp, cluster_type, cluster_name, workspace_resource_id, extensionSettings, enableHighLogScaleMode)
         elif not _is_container_insights_solution_exists(cmd, workspace_resource_id):
             logger.info("Creating ContainerInsights solution resource, since it doesn't exist and it is using legacy authentication")
             _ensure_container_insights_for_monitoring(cmd, workspace_resource_id).result()
@@ -597,6 +655,37 @@ def _get_container_insights_settings(cmd, cluster_resource_group_name, cluster_r
         configuration_settings['amalogs.domain'] = 'opinsights.azure.microsoft.scloud'
 
 
+def _delete_dce_for_dcr(cmd, subscription_id, cluster_resource_group_name, dcr_config):
+    """Delete Data Collection Endpoint associated with a DCR if it exists"""
+    try:
+        if ("properties" in dcr_config and 
+            "dataCollectionEndpointId" in dcr_config["properties"] and 
+            dcr_config["properties"]["dataCollectionEndpointId"]):
+            
+            dce_id = dcr_config["properties"]["dataCollectionEndpointId"]
+            dce_parts = dce_id.split('/')
+
+            if len(dce_parts) > 0:
+                dce_name = dce_parts[-1]
+                dce_resource_id = f"/subscriptions/{subscription_id}/resourceGroups/{cluster_resource_group_name}/providers/Microsoft.Insights/dataCollectionEndpoints/{dce_name}"
+                dce_url = cmd.cli_ctx.cloud.endpoints.resource_manager + f"{dce_resource_id}?api-version=2022-06-01"              
+                # Try to delete up to 3 times
+                for retry in range(3):
+                    try:
+                        send_raw_request(cmd.cli_ctx, "DELETE", dce_url)
+                        logger.info("Successfully deleted DCE: %s", dce_name)
+                        return True
+                    except CLIError as e:
+                        if "ResourceNotFound" in str(e):
+                            return True
+                        if retry == 2:
+                            logger.warning("Failed to delete DCE: %s - %s", dce_name, str(e))
+                            return False
+                        logger.info("Retrying DCE deletion after error: %s", str(e))
+    except CLIError:
+        pass
+    return True
+
 def get_existing_container_insights_extension_dcr_tags(cmd, dcr_url):
     tags = {}
     _MAX_RETRY_TIMES = 3
@@ -617,7 +706,7 @@ def get_existing_container_insights_extension_dcr_tags(cmd, dcr_url):
     return tags
 
 
-def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_resource_group_name, cluster_rp, cluster_type, cluster_name, workspace_resource_id, extensionSettings):
+def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_resource_group_name, cluster_rp, cluster_type, cluster_name, workspace_resource_id, extensionSettings, enable_high_log_scale_mode):
     from azure.core.exceptions import HttpResponseError
 
     cluster_region = ''
@@ -652,6 +741,18 @@ def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_
     dataCollectionRuleName = dataCollectionRuleName[0:64]
     dcr_resource_id = f"/subscriptions/{subscription_id}/resourceGroups/{cluster_resource_group_name}/providers/Microsoft.Insights/dataCollectionRules/{dataCollectionRuleName}"
 
+    # ingestion DCE MUST be in workspace region
+    ingestionDataCollectionEndpointName = f"MSCI-ingest-{workspace_region}-{cluster_name}"
+    # Max length of the DCE name is 43 chars
+    ingestionDataCollectionEndpointName = _trim_suffix_if_needed(ingestionDataCollectionEndpointName[0:43])
+    ingestion_dce_resource_id = None
+
+    # create ingestion DCE if high log scale mode enabled
+    if enable_high_log_scale_mode:
+        ingestion_dce_resource_id = create_data_collection_endpoint(
+            cmd, subscription_id, cluster_resource_group_name, workspace_region, ingestionDataCollectionEndpointName
+        )
+
     # first get the association between region display names and region IDs (because for some reason
     # the "which RPs are available in which regions" check returns region display names)
     region_names_to_id = {}
@@ -677,6 +778,8 @@ def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_
     # get existing tags on the container insights extension DCR if the customer added any
     existing_tags = get_existing_container_insights_extension_dcr_tags(cmd, dcr_url)
     streams = ["Microsoft-ContainerInsights-Group-Default"]
+    if enable_high_log_scale_mode:
+        streams = ContainerInsightsStreams
     if extensionSettings is None:
         extensionSettings = {}
     if 'dataCollectionSettings' in extensionSettings.keys():
@@ -691,6 +794,11 @@ def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_
         }
     extensionSettings["dataCollectionSettings"] = dataCollectionSettings
 
+    if enable_high_log_scale_mode:
+        for i, v in enumerate(streams):
+            if v == "Microsoft-ContainerLogV2":
+                streams[i] = "Microsoft-ContainerLogV2-HighScale"
+
     # create the DCR
     dcr_creation_body = json.dumps(
         {
@@ -722,6 +830,7 @@ def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_
                         }
                     ]
                 },
+                "dataCollectionEndpointId": ingestion_dce_resource_id
             },
         }
     )
@@ -755,3 +864,34 @@ def _ensure_container_insights_dcr_for_monitoring(cmd, subscription_id, cluster_
             error = e
         else:
             raise error
+
+
+def create_data_collection_endpoint(cmd, subscription_id, cluster_resource_group_name, workspace_region, ingestionDataCollectionEndpointName):
+    # create the ingestion DCE
+    ingestion_dce_resource_id = f"/subscriptions/{subscription_id}/resourceGroups/{cluster_resource_group_name}/providers/Microsoft.Insights/dataCollectionEndpoints/{ingestionDataCollectionEndpointName}"
+    ingestion_dce_url = cmd.cli_ctx.cloud.endpoints.resource_manager + f"{ingestion_dce_resource_id}?api-version=2022-06-01"
+    ingestion_dce_creation_body = json.dumps({
+        "location": workspace_region,
+        "kind": "Linux",
+        "properties": {
+            "networkAcls": {
+                "publicNetworkAccess": "Enabled"
+            }
+        }
+    })
+    error = None
+    for _ in range(3):
+        try:
+            send_raw_request(cmd.cli_ctx, "PUT", ingestion_dce_url, body=ingestion_dce_creation_body)
+            return ingestion_dce_resource_id
+        except AzCLIError as e:
+            error = e
+    if error:
+        raise error
+    return ingestion_dce_resource_id
+
+
+def _trim_suffix_if_needed(s, suffix="-"):
+    if s.endswith(suffix):
+        s = s[:-len(suffix)]
+    return s
diff --git a/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale.yaml b/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale.yaml
new file mode 100644
index 00000000000..f19e4cd2a41
--- /dev/null
+++ b/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale.yaml
@@ -0,0 +1,49 @@
+interactions:
+- request:
+    body: null
+    headers:
+      Accept:
+      - application/json
+      Accept-Encoding:
+      - gzip, deflate
+      CommandName:
+      - k8s-extension create
+      Connection:
+      - keep-alive
+      ParameterSetName:
+      - -g -n -c --cluster-type --extension-type --configuration-settings
+      User-Agent:
+      - AZURECLI/2.75.0 azsdk-python-core/1.31.0 Python/3.10.12 (Linux-6.6.87.2-microsoft-standard-WSL2-x86_64-with-glibc2.35)
+    method: GET
+    uri: https://management.azure.com/subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/azurecli-tests/providers/Microsoft.Kubernetes/connectedClusters/arc-cluster?api-version=2020-01-01-preview
+  response:
+    body:
+      string: '{"error":{"code":"ResourceGroupNotFound","message":"Resource group
+        ''azurecli-tests'' could not be found."}}'
+    headers:
+      cache-control:
+      - no-cache
+      content-length:
+      - '106'
+      content-type:
+      - application/json; charset=utf-8
+      date:
+      - Tue, 01 Jul 2025 18:42:31 GMT
+      expires:
+      - '-1'
+      pragma:
+      - no-cache
+      strict-transport-security:
+      - max-age=31536000; includeSubDomains
+      x-cache:
+      - CONFIG_NOCACHE
+      x-content-type-options:
+      - nosniff
+      x-ms-failure-cause:
+      - gateway
+      x-msedge-ref:
+      - 'Ref A: 43ED95238AFF4CEA964D74A2529E4C51 Ref B: BL2AA2011005060 Ref C: 2025-07-01T18:42:32Z'
+    status:
+      code: 404
+      message: Not Found
+version: 1
diff --git a/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale_streams.yaml b/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale_streams.yaml
new file mode 100644
index 00000000000..4f45cd12fd2
--- /dev/null
+++ b/src/k8s-extension/azext_k8s_extension/tests/latest/recordings/test_container_insights_high_log_scale_streams.yaml
@@ -0,0 +1,49 @@
+interactions:
+- request:
+    body: null
+    headers:
+      Accept:
+      - application/json
+      Accept-Encoding:
+      - gzip, deflate
+      CommandName:
+      - k8s-extension create
+      Connection:
+      - keep-alive
+      ParameterSetName:
+      - -g -n -c --cluster-type --extension-type --configuration-settings
+      User-Agent:
+      - AZURECLI/2.75.0 azsdk-python-core/1.31.0 Python/3.10.12 (Linux-6.6.87.2-microsoft-standard-WSL2-x86_64-with-glibc2.35)
+    method: GET
+    uri: https://management.azure.com/subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/azurecli-tests/providers/Microsoft.Kubernetes/connectedClusters/arc-cluster?api-version=2020-01-01-preview
+  response:
+    body:
+      string: '{"error":{"code":"ResourceGroupNotFound","message":"Resource group
+        ''azurecli-tests'' could not be found."}}'
+    headers:
+      cache-control:
+      - no-cache
+      content-length:
+      - '106'
+      content-type:
+      - application/json; charset=utf-8
+      date:
+      - Tue, 01 Jul 2025 18:42:31 GMT
+      expires:
+      - '-1'
+      pragma:
+      - no-cache
+      strict-transport-security:
+      - max-age=31536000; includeSubDomains
+      x-cache:
+      - CONFIG_NOCACHE
+      x-content-type-options:
+      - nosniff
+      x-ms-failure-cause:
+      - gateway
+      x-msedge-ref:
+      - 'Ref A: BEEC6FA3AAA44D3B923946D0F5FF610C Ref B: BL2AA2011006062 Ref C: 2025-07-01T18:42:32Z'
+    status:
+      code: 404
+      message: Not Found
+version: 1
diff --git a/src/k8s-extension/azext_k8s_extension/tests/latest/test_k8s_extension_scenario.py b/src/k8s-extension/azext_k8s_extension/tests/latest/test_k8s_extension_scenario.py
index c0436d709fb..53e2482abbc 100644
--- a/src/k8s-extension/azext_k8s_extension/tests/latest/test_k8s_extension_scenario.py
+++ b/src/k8s-extension/azext_k8s_extension/tests/latest/test_k8s_extension_scenario.py
@@ -6,12 +6,11 @@
 # pylint: disable=line-too-long
 
 import os
+import json
 from azure.cli.testsdk import (ScenarioTest, record_only)
 
-
 TEST_DIR = os.path.abspath(os.path.join(os.path.abspath(__file__), '..'))
 
-
 class K8sExtensionScenarioTest(ScenarioTest):
     @record_only()
     def test_k8s_extension(self):
@@ -60,3 +59,68 @@ def test_k8s_extension(self):
                 found_extension = True
                 break
         self.assertFalse(found_extension)
+
+
+class ContainerInsightsExtensionTest(ScenarioTest):
+    @record_only()
+    def test_container_insights_high_log_scale(self):
+        from azure.core.exceptions import ResourceNotFoundError
+        
+        self.kwargs.update({
+            'name': 'azuremonitor-containers',
+            'rg': 'azurecli-tests',
+            'cluster_name': 'arc-cluster',
+            'cluster_type': 'connectedClusters',
+            'extension_type': 'microsoft.azuremonitor.containers',
+            'config_settings': '"amalogs.useAADAuth=true amalogs.enableHighLogScaleMode=true ' + 
+                             'dataCollectionSettings=' + json.dumps({
+                                 'interval': '1m',
+                                 'enableContainerLogV2': True,
+                                 'streams': ['Microsoft-ContainerLogV2']
+                             }) + '"'
+        })
+        # Test creating extension with high log scale enabled
+        with self.assertRaisesRegexp(ResourceNotFoundError, "Resource group 'azurecli-tests' could not be found"):
+            self.cmd('k8s-extension create -g {rg} -n {name} -c {cluster_name} --cluster-type {cluster_type} '
+                    '--extension-type {extension_type} --configuration-settings {config_settings}')
+
+    @record_only()
+    def test_container_insights_invalid_high_log_scale(self):
+        self.kwargs.update({
+            'name': 'azuremonitor-containers',
+            'rg': 'azurecli-tests',
+            'cluster_name': 'arc-cluster',
+            'cluster_type': 'connectedClusters',
+            'extension_type': 'microsoft.azuremonitor.containers'
+        })
+
+        # Test that invalid high log scale mode value is rejected
+        with self.assertRaisesRegexp(Exception, 'amalogs.enableHighLogScaleMode value MUST be either true or false'):
+            self.cmd('k8s-extension create -g {rg} -n {name} -c {cluster_name} --cluster-type {cluster_type} '
+                    '--extension-type {extension_type} '
+                    '--configuration-settings '
+                    'amalogs.useAADAuth=true '
+                    'amalogs.enableHighLogScaleMode=invalid')
+
+    @record_only()
+    def test_container_insights_high_log_scale_streams(self):
+        from azure.core.exceptions import ResourceNotFoundError
+        
+        self.kwargs.update({
+            'name': 'azuremonitor-containers',
+            'rg': 'azurecli-tests',
+            'cluster_name': 'arc-cluster',
+            'cluster_type': 'connectedClusters',
+            'extension_type': 'microsoft.azuremonitor.containers',
+            'config_settings': '"amalogs.useAADAuth=true amalogs.enableHighLogScaleMode=true ' +
+                             'dataCollectionSettings=' + json.dumps({
+                                 'interval': '1m',
+                                 'enableContainerLogV2': True,
+                                 'streams': ['Microsoft-ContainerLogV2', 'Microsoft-ContainerLog']
+                             }) + '"'
+        })
+
+        # Test creating extension with high log scale enabled and multiple streams
+        with self.assertRaisesRegexp(ResourceNotFoundError, "Resource group 'azurecli-tests' could not be found"):
+            self.cmd('k8s-extension create -g {rg} -n {name} -c {cluster_name} --cluster-type {cluster_type} '
+                    '--extension-type {extension_type} --configuration-settings {config_settings}')
diff --git a/src/k8s-extension/setup.py b/src/k8s-extension/setup.py
index c46e1aca890..bdee2be8241 100644
--- a/src/k8s-extension/setup.py
+++ b/src/k8s-extension/setup.py
@@ -33,7 +33,7 @@
 # TODO: Add any additional SDK dependencies here
 DEPENDENCIES = []
 
-VERSION = "1.6.5"
+VERSION = "1.6.6"
 
 with open("README.rst", "r", encoding="utf-8") as f:
     README = f.read()
diff --git a/testing/pipeline/k8s-custom-pipelines.yml b/testing/pipeline/k8s-custom-pipelines.yml
index 0cc9895583a..8fe39c8728d 100644
--- a/testing/pipeline/k8s-custom-pipelines.yml
+++ b/testing/pipeline/k8s-custom-pipelines.yml
@@ -35,6 +35,10 @@ stages:
     parameters:
       jobName: AzureMonitor
       path: ./test/extensions/public/AzureMonitor.Tests.ps1
+  - template: ./templates/run-test.yml
+    parameters:
+      jobName: AzureMonitorHighScale
+      path: ./test/extensions/public/AzureMonitorHighScale.Tests.ps1
   - template: ./templates/run-test.yml
     parameters:
       jobName: AzurePolicy
diff --git a/testing/test/extensions/public/AzureMonitorHighScale.Tests.ps1 b/testing/test/extensions/public/AzureMonitorHighScale.Tests.ps1
new file mode 100644
index 00000000000..183bfb6b476
--- /dev/null
+++ b/testing/test/extensions/public/AzureMonitorHighScale.Tests.ps1
@@ -0,0 +1,126 @@
+Describe 'Azure Monitor High Scale Mode Testing' {
+    BeforeAll {
+        $extensionType = "microsoft.azuremonitor.containers"
+        $extensionName = "azuremonitor-containers"
+        $extensionAgentName = "omsagent"
+        $extensionAgentNamespace = "kube-system"
+        
+        . $PSScriptRoot/../../helper/Constants.ps1
+        . $PSScriptRoot/../../helper/Helper.ps1
+    }
+
+    It 'Creates the extension with high log scale mode and verifies DCE creation' {
+        # Create extension with high scale mode enabled
+        az $Env:K8sExtensionName create -c $($ENVCONFIG.arcClusterName) -g $($ENVCONFIG.resourceGroup) `
+            --cluster-type connectedClusters --extension-type $extensionType -n $extensionName `
+            --configuration-settings "amalogs.enableHighLogScaleMode=true" --no-wait
+        $? | Should -BeTrue
+
+        # Verify extension creation
+        $output = az $Env:K8sExtensionName show -c $($ENVCONFIG.arcClusterName) -g $($ENVCONFIG.resourceGroup) --cluster-type connectedClusters -n $extensionName
+        $? | Should -BeTrue
+
+        $extension = ($output | ConvertFrom-Json)
+        $extension | Should -Not -BeNullOrEmpty
+        
+        # Verify high scale mode configuration
+        $settings = $extension.configurationSettings
+        $settings.'amalogs.enableHighLogScaleMode' | Should -Be "true"
+        $settings.'amalogs.useAADAuth' | Should -Be "true"
+
+        # Wait for extension to install
+        $n = 0
+        do {
+            if (Has-ExtensionData $extensionName) {
+                break
+            }
+            Start-Sleep -Seconds 10
+            $n += 1
+        } while ($n -le $MAX_RETRY_ATTEMPTS)
+        $n | Should -BeLessOrEqual $MAX_RETRY_ATTEMPTS
+
+        # Verify DCE creation
+        $clusterLocation = (az resource show -g $($ENVCONFIG.resourceGroup) -n $($ENVCONFIG.arcClusterName) --resource-type "Microsoft.Kubernetes/connectedClusters" --query location -o tsv).ToLower()
+        $dceName = "MSCI-ingest-$clusterLocation-$($ENVCONFIG.arcClusterName)"
+        if ($dceName.Length -gt 43) {
+            $dceName = $dceName.Substring(0, 43)
+            # Remove trailing hyphen if present
+            if ($dceName.EndsWith("-")) {
+                $dceName = $dceName.Substring(0, $dceName.Length - 1)
+            }
+        }
+        
+        $dce = az monitor data-collection endpoint show -g $($ENVCONFIG.resourceGroup) -n $dceName
+        $? | Should -BeTrue
+        $dce | Should -Not -BeNullOrEmpty
+        
+        # Verify DCE configuration
+        $dceObj = ($dce | ConvertFrom-Json)
+        $dceObj.kind | Should -Be "Linux"
+        $dceObj.properties.networkAcls.publicNetworkAccess | Should -Be "Enabled"
+    }
+
+    It "Verifies Data Collection Rule configuration for high scale mode" {
+        # Get the DCR name
+        $clusterLocation = (az resource show -g $($ENVCONFIG.resourceGroup) -n $($ENVCONFIG.arcClusterName) --resource-type "Microsoft.Kubernetes/connectedClusters" --query location -o tsv).ToLower()
+        $dcrName = "MSCI-$clusterLocation-$($ENVCONFIG.arcClusterName)"
+        if ($dcrName.Length -gt 64) {
+            $dcrName = $dcrName.Substring(0, 64)
+        }
+
+        # Get the DCR
+        $dcr = az monitor data-collection rule show -g $($ENVCONFIG.resourceGroup) -n $dcrName
+        $? | Should -BeTrue
+        $dcr | Should -Not -BeNullOrEmpty
+
+        # Verify high scale mode streams configuration
+        $dcrObj = ($dcr | ConvertFrom-Json)
+        $streams = $dcrObj.properties.dataSources.extensions[0].streams
+        $streams | Should -Contain "Microsoft-ContainerLogV2-HighScale"
+        $streams | Should -Contain "Microsoft-KubeEvents"
+        $streams | Should -Contain "Microsoft-KubePodInventory"
+        $streams | Should -Contain "Microsoft-KubeNodeInventory"
+        $streams | Should -Contain "Microsoft-KubePVInventory"
+        $streams | Should -Contain "Microsoft-KubeServices"
+        $streams | Should -Contain "Microsoft-KubeMonAgentEvents"
+        $streams | Should -Contain "Microsoft-InsightsMetrics"
+        $streams | Should -Contain "Microsoft-ContainerInventory"
+        $streams | Should -Contain "Microsoft-ContainerNodeInventory"
+        $streams | Should -Contain "Microsoft-Perf"
+    }
+
+    It "Deletes the extension and verifies DCE cleanup" {
+        # Get DCE name before deletion
+        $clusterLocation = (az resource show -g $($ENVCONFIG.resourceGroup) -n $($ENVCONFIG.arcClusterName) --resource-type "Microsoft.Kubernetes/connectedClusters" --query location -o tsv).ToLower()
+        $dceName = "MSCI-ingest-$clusterLocation-$($ENVCONFIG.arcClusterName)"
+        if ($dceName.Length -gt 43) {
+            $dceName = $dceName.Substring(0, 43)
+            # Remove trailing hyphen if present
+            if ($dceName.EndsWith("-")) {
+                $dceName = $dceName.Substring(0, $dceName.Length - 1)
+            }
+        }
+
+        # Delete the extension
+        $output = az $Env:K8sExtensionName delete -c $($ENVCONFIG.arcClusterName) -g $($ENVCONFIG.resourceGroup) --cluster-type connectedClusters -n $extensionName --force
+        $? | Should -BeTrue
+
+        # Verify extension is deleted
+        $output = az $Env:K8sExtensionName show -c $($ENVCONFIG.arcClusterName) -g $($ENVCONFIG.resourceGroup) --cluster-type connectedClusters -n $extensionName
+        $? | Should -BeFalse
+        $output | Should -BeNullOrEmpty
+
+        # Verify DCE is deleted
+        $dce = az monitor data-collection endpoint show -g $($ENVCONFIG.resourceGroup) -n $dceName
+        $? | Should -BeFalse
+    }
+
+    It "Performs another list after the delete" {
+        $output = az $Env:K8sExtensionName list -c $($ENVCONFIG.arcClusterName) -g $($ENVCONFIG.resourceGroup) --cluster-type connectedClusters
+        $? | Should -BeTrue
+        $output | Should -Not -BeNullOrEmpty
+        
+        $extensionExists = $output | ConvertFrom-Json | Where-Object { $_.extensionType -eq $extensionName }
+        $extensionExists | Should -BeNullOrEmpty
+    }
+}