@David Thielen](/users/na/?userid=2e000d14-7fa3-4e41-9299-8306855b228f) Thanks for your response. Please find the below response for your follow questions.
The 12 hours information related to storing the logs in file system is for temporary and debugging purpose only and for long retention you need to either use application insights or enabling diagnostic settings would be helpful. Even your webapp is scaled out to 4 or N (number of instances) application insights will be able to scale along with the App Service as it becomes part of Application and its setting.
Questions related to Diagnostics settings:
1.Anything I should add to my ILogger message format configuration to identify the server each log message came from?
A: To distinguish/identify the source of logs, you can configure telemetry.Context.Cloud.RoleName
and telemetry.Context.Cloud.RoleInstance
in your application telemetry configuration as mentioned here.
2.Messages from all servers will all go to the same blog - correct?
A: Based on my tests, we have observed that an individual blob file will be generated for each instance.
3.Any suggestions on how I should configure the disgnostic settings to save everything to the blob.
A: While enabling the diagnostic settings select the destination as Storage account to send webapp logs as shown below.
4.Any suggestions on what tool(s) I should use to review the blob?
A: If you store logs in storage account you manually need to review it and if you store the logs in application insights you can query them using some KQL queries.
Feel free to reach back to me if you have any further questions on this.