I new to Azure and am running about 20 websites ( web apps ) on an Azure B1 Basic, 1 Core, 1.75 GB RAM, 10 GB Storage instance. They are very low traffic sites with tens of visits daily.
The sites include one page static holding pages, some Umbraco sites using SQL Server or SQLLite and a couple of WordPress sites using MySQL(In App). One site uses an extension to get a free Lets encrypt ssl certificate.
The app service is using around 2GB of the 10Gb of storage and memory usage sits around 60%.
Every few weeks a random few of the sites will go down with an http 500 error for a few minutes spread over a period of half an hour or longer. I use uptime robot monitoring so see the email notifications come in. Some sites seem to be more likely than others to restart. Occasionally a site won't restart throwing the 500 error until I go and do it manually. I need to turn off 'always on' to get them to restart without the error.
I have used 'Diagnose and solve problems' and got the following issues reported.
Reasons for your web app restart
Around 9/19/2017 9:22:21 PM (UTC), On Instance RD0003FF1C76E9, Your application was recycled due to an intermittent Azure infrastructure issue while accessing remote file storage. This can happen due to multiple reasons like platform instances getting upgraded or instance(s) experiencing high latencies accessing the remote storage. In case the instance(s) where your application is running is experiencing high latencies accessing remote storage, platform tries to heal your application by switching to different remote storage which is having low latency. This can also cause the application process to restart. If this is a one off occurrence, then no further action plan is needed from your side. But if you see it occur frequently, then enabling local cache feature can help reduce dependency on storage file servers to some extent.
Explore App Service Local Cache (https://docs.microsoft.com/en-gb/azure/app-service/app-service-local-cache-overview)
On Instance RD0003FF1C95DF, Your application was recycled as the Azure scale unit was undergoing an upgrade. This event occurred multiple times during the day. There are periodic updates made by Microsoft to the underlying Azure platform to improve overall reliability, performance, and security of the platform infrastructure where your application is running on. Most of these updates are performed without any impact upon your web app. To reduce the impact of such events on your application, consider deploying your application to multiple regions and use Azure Traffic Manager to distribute the load across regions.
Explore Azure Traffic Manager (https://docs.microsoft.com/en-gb/azure/app-service/web-sites-traffic-manager)
Is there anything I can do to fix this? Is the suggested local cache safe to use on a content manged site?
Is this just normal service from Azure or is this unusual.
Thanks
Best Answer
As your issue report said,
Azure need infrastructure to be upgraded and keep your resource healthy at the same time. So, it recycle your Apps at random to reach that .
For now ,we should wait azure finishing this upgrade. We cannot fix that due to it's about Azure infrastructure issue. This would not cost too much time.Using Azure VM or Web App service is quite safe to hold your Apps on Cloud.
App Service Local Cache can be used for Azure Web App Service. According to your issue , You needn't use this feature because your Apps is running on an Azure VM . After this upgrade , all your apps would be running well.