Create elastic-san-troubleshoot.md

Creating TSG doc for Elastic SAN

Author: adarshv98

articles/storage/elastic-san/elastic-san-troubleshoot.md

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+---
+title: Troubleshoot Azure Elastic SAN
+description: Troubleshoot issues with Azure Elastic SAN
+author: adarshv98
+ms.service: azure-elastic-san-storage
+ms.topic: how-to
+ms.date: 04/15/2025
+ms.author: adarshv98
+---
+
+# Troubleshoot Elastic SAN
+
+This article lists common issues related to Azure Elastic SAN. It also provides possible causes and resolutions for these issues.
+
+## Encountered get_iqns timeout error with Linux documentation script - Exception: Command took longer than 10s
+
+- Install the latest Azure CLI. Please follow the instructions that work for your VM SKU.
+- Once you've installed the latest version, run az extension add -n elastic-san to install the extension for Elastic SAN. 
+- Run the az login command and follow the steps that command generates to login through your browser.
+- Rerun the Linux documentation script script
+
+## Encountered login rejected error - iscsiadm: Cannot modify node.conn[0].iscsi.DataDigest. Invalid param name. 
+
+- Ensure the private endpoint or service endpoint is configured correctly 
+- Check if your volumes are being attached either to AVS (CRC not supported yet) or Fedora or its downstream Linux distributions like Red Hat Enterprise Linux, CentOS, Rocky Linux, etc. that don't support data digests. If they are, disable the CRC protection flag. Note that you will have to uncheck the box on portal and change the parameter for EnforceDataIntegrityCheckForIscsi (PSH) or data-integrity-check (CLI) to false.
+
+## Unable to connect to your Elastic SAN via service endpoints
+
+- Enable Public Network Access on the SAN (https://learn.microsoft.com/en-us/azure/storage/elastic-san/elastic-san-networking?tabs=azure-powershell#configure-public-network-access)
+```powershell
+# Set the variable values.
+$RgName       = "<ResourceGroupName>"
+$EsanName     = "<ElasticSanName>"
+# Update the Elastic San.
+Update-AzElasticSan -Name $EsanName -ResourceGroupName $RgName -PublicNetworkAccess Enabled
+```
+- Configure service endpoints on the volume group (https://learn.microsoft.com/en-us/azure/storage/elastic-san/elastic-san-networking?tabs=azure-powershell#configure-an-azure-storage-service-endpoint)
+```powershell
+# Define some variables
+$RgName = "<ResourceGroupName>" 
+$VnetName = "<VnetName>" 
+$SubnetName = "<SubnetName>" 
+# Get the virtual network and subnet 
+$Vnet = Get-AzVirtualNetwork -ResourceGroupName $RgName -Name $VnetName $Subnet = Get-AzVirtualNetworkSubnetConfig -VirtualNetwork $Vnet -Name $SubnetName 
+# Enable the storage service endpoint 
+$Vnet | Set-AzVirtualNetworkSubnetConfig -Name $SubnetName -AddressPrefix $Subnet.AddressPrefix -ServiceEndpoint "Microsoft.Storage.Global" | Set-AzVirtualNetwork
+```
+
+## Elastic SAN volume performance or latency is not as expected
+
+- Check your SAN size and configuration via portal (SAN homepage -> Configuration blade) and ensure that the IOPS and throughput numbers can handle the requirements of the workload
+-  Check your VM throughput and IOPS limits and ensure that the VM can handle the workload requirements
+- Ensure that you are following the best practices outlined in this [document](https://learn.microsoft.com/en-us/azure/storage/elastic-san/elastic-san-best-practices). 
+
+
+## Unable to establish connectivity from new nodes in a cluster
+
+- Identify which VMs are part of the cluster.
+- Check the number of sessions per node using iscsicli sessionList or mpclaim -s -d (for Windows) or sudo multipath -ll (for Linux) on each VM in the cluster and add up the total number of sessions
+- After doing so, if the # of sessions is 128 then you can disconnect the volumes via portal or using the script linked [here](https://github.com/Azure-Samples/azure-elastic-san/blob/main/PSH%20(Windows)%20Multi-Session%20Connect%20Scripts/ElasticSanDocScripts0523/disconnect.ps1) for Windows and [here](https://github.com/Azure-Samples/azure-elastic-san/blob/main/CLI%20(Linux)%20Multi-Session%20Connect%20Scripts/disconnect_for_documentation.py) for Linux. Then modify the NumSession parameter (Windows) or the num_of_sessions parameter (Linux) of the connect script (either from portal or the [Windows](https://github.com/Azure-Samples/azure-elastic-san/blob/main/PSH%20(Windows)%20Multi-Session%20Connect%20Scripts/ElasticSanDocScripts0523/connect.ps1)/[Linux](https://github.com/Azure-Samples/azure-elastic-san/blob/main/CLI%20(Linux)%20Multi-Session%20Connect%20Scripts/connect_for_documentation.py) scripts) to have the right # of sessions per volume such that the total is less than 128 and run it on the VM. This can also be entered during runtime of the script.
+
+## Unable to connect to more than 8 volumes to a Windows VM
+
+- Run iscsicli sessionList or mpclaim -s -d on your Windows VM to see the number of sessions. Max session limit is 255.
+- If you are at the limit, then you can disconnect the volumes via portal or using the script linked [here](https://github.com/Azure-Samples/azure-elastic-san/blob/main/PSH%20(Windows)%20Multi-Session%20Connect%20Scripts/ElasticSanDocScripts0523/disconnect.ps1) for Windows. Then modify the $NumSession parameter of the connect script (either from portal or the [Windows](https://github.com/Azure-Samples/azure-elastic-san/blob/main/PSH%20(Windows)%20Multi-Session%20Connect%20Scripts/ElasticSanDocScripts0523/connect.ps1) script) to have the right # of sessions per volume such that the total is less than 255 sessions and run it on the VM. This can also be entered during runtime of the script.
+
+## Need help?
+If you still need help, [contact support](https://portal.azure.com/?#blade/Microsoft_Azure_Support/HelpAndSupportBlade) to get your problem resolved quickly.