Store and view diagnostic data in Azure Storage

Article
08/19/2024

Important

Cloud Services (classic) is now deprecated for all customers as of September 1st, 2024. Any existing running deployments will be stopped and shut down by Microsoft and the data will be permanantly lost starting October 2024. New deployments should use the new Azure Resource Manager based deployment model Azure Cloud Services (extended support).

Diagnostic data isn't permanently stored unless you transfer it to the Microsoft Azure Storage Emulator or to Azure Storage. Once in storage, it can be viewed with one of several available tools.

Specify a storage account

You specify the storage account that you want to use in the ServiceConfiguration.cscfg file. The account information is defined as a connection string in a configuration setting. The following example shows the default connection string created for a new Cloud Service project in Visual Studio:

    <ConfigurationSettings>
       <Setting name="Microsoft.WindowsAzure.Plugins.Diagnostics.ConnectionString" value="UseDevelopmentStorage=true" />
    </ConfigurationSettings>

You can change this connection string to provide account information for an Azure storage account.

Depending on the type of diagnostic data that is being collected, Azure Diagnostics uses either the Blob service or the Table service. The following table shows the data sources that are persisted and their format.

Data source	Storage format
Azure logs	Table
IIS 7.0 logs	Blob
Azure Diagnostics infrastructure logs	Table
Failed Request Trace logs	Blob
Windows Event logs	Table
Performance counters	Table
Crash dumps	Blob
Custom error logs	Blob

Transfer diagnostic data

For SDK 2.5 and later, the request to transfer diagnostic data can occur through the configuration file. You can transfer diagnostic data at scheduled intervals as specified in the configuration.

For SDK 2.4 and earlier, you can request to transfer the diagnostic data programmatically and through the configuration file. The programmatic approach also allows you to do on-demand transfers.

Important

When you transfer diagnostic data to an Azure storage account, you incur costs for the storage resources that your diagnostic data uses.

Store diagnostic data

Log data is stored in either Blob or Table storage with the following names:

Tables

WadLogsTable - Logs written in code using the trace listener.
WADDiagnosticInfrastructureLogsTable - Diagnostic monitor and configuration changes.
WADDirectoriesTable – Directories that the diagnostic monitor is monitoring. These directories include IIS logs, IIS failed request logs, and custom directories. The location of the blob log file is specified in the Container field and the name of the blob is in the RelativePath field. The AbsolutePath field indicates the location and name of the file as it existed on the Azure virtual machine.
WADPerformanceCountersTable – Performance counters.
WADWindowsEventLogsTable – Windows Event logs.

Blobs

wad-control-container – (Only for SDK 2.4 and previous) Contains the XML configuration files that control the Azure diagnostics.
wad-iis-failedreqlogfiles – Contains information from IIS Failed Request logs.
wad-iis-logfiles – Contains information about IIS logs.
"custom" – A custom container based on configuring directories that are monitored by the diagnostic monitor. WADDirectoriesTable specifies the name of this blob container.

Tools to view diagnostic data

Several tools are available to view the data after it transfers to storage. For example:

Server Explorer in Visual Studio - If you installed the Azure Tools for Microsoft Visual Studio, you can use the Azure Storage node in Server Explorer to view read-only blob and table data from your Azure storage accounts. You can display data from your local storage emulator account and also from storage accounts you created for Azure. For more information, see Browsing and Managing Storage Resources with Server Explorer.
Microsoft Azure Storage Explorer is a standalone app that enables you to easily work with Azure Storage data on Windows, OSX, and Linux.
Azure Management Studio includes Azure Diagnostics Manager, which allows you to view, download, and manage the diagnostics data collected by the applications running on Azure.

Next Steps

Trace the flow in a Cloud Services application with Azure Diagnostics

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