App Service c:\local space question

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App Service c:\local space question

Jeff Tucker 90

Hi,

We recently setup monitoring to alert us if the c:\local space on our Windows based App Service was getting low. We used the details from an earlier post which worked quite well: https://learn.microsoft.com/en-us/answers/questions/1328576/how-to-monitor-storage-space-on-app-services

Our issue now, is that we have detected low free space on our c:\local folder, but we cannot seem to identify what is taking the space. When we monitor this over time, we see the free space slowly going down until it will eventually go to zero. However, if we try to look at all the files themselves, it adds up to a much smaller number and also remains static over time. So it seems that something else is taking the space, but we cannot seem to find what that is.

For reference, the PowerShell we were using to measure the space was the following:

(Get-ChildItem -path c:\local -Recurse -Force -ErrorAction SilentlyContinue | Measure-Object -Property Length -Sum).sum

Any ideas on what is taking this space and how we can find it?

It also is worth noting that if we redeploy the application, that in that case the space gets reset. This also happens if we scale the app service plan up and then back down (although this seems more expected to me, since that is changing the machine size behind the scenes). Doing an advanced application restart does not reclaim any space however.

Any advice or suggestions?

SnehaAgrawal-MSFT 22,706 Reputation points Moderator

2024-01-04T16:51:04.16+00:00

@Jeff Tucker Thanks for asking question!

You may want to know that App Service is a service running on top of the Azure PaaS (platform as a service) infrastructure. As a result, the local drives that are "attached" to a virtual machine are the same drive types available to any worker role running in Azure. This includes:

• An operating system drive (the D:\ drive)
• An application drive that contains Azure Package cspkg files used exclusively by App Service (and inaccessible to customers)
• A "user" drive (the C:\ drive), whose size varies depending on the size of the VM.

So, Its important to monitor your disk utilization as your application grows. If the disk quota is reached, it can have adverse effects to your application. For example:

• The app may throw an error indicating not enough space on the disk.
• You may see disk errors when browsing to the Kudu console.
• Deployment from Azure DevOps or Visual Studio may fail with ERROR_NOT_ENOUGH_DISK_SPACE: Web deployment task failed.
(Web Deploy detected insufficient space on disk).
• Your app may suffer slow performance.

You can monitor the disk space under “Quotas” tab at the Web App level. Go to Web App -> Quotas -> you can see the File System Storage.

Also, try checking the App Service Plan quotas by going to App service plan and selecting Quotas. Additionally suggest you to check the application files in the D:\home\site\wwwroot from the Azure kudu tool (https://yoursite.scm.azurewebsites.net/) and available disk space on the Environment page. You may try increasing the pricing tier plan and see if that helps to resolve the issue.

Also, Please check below articles on this:

Azure App Service - What is taking my disk space for my Azure Web App ?

Review and manage your web site disk space in Azure

Disclaimer: This response contains a reference to a third-party World Wide Web site. Microsoft is providing this information as a convenience to you.

Let us know if further query.
Jeff Tucker 90 Reputation points

2024-01-04T19:46:28.48+00:00

Thanks for the information. It does not seem that the Quota information covers the c:\local folder from what I can see. When we check this, it always seems that the quota is referring to the overall larger storage, and as a result always shows very low usage. But the c:\local folder has a specific size limit and this is the folder that we are running into issues with.

I will take a look at the extension mentioned in the second article. I haven't used extensions before (paranoid from a security perspective), but will take a look at the code and will see if that can help narrow down the source.

Also, just to help give more context to my original description, here is a screenshot showing the current state of this app in question. As you can see the c:\home folder is fine - no issue at all there. But the c:\local is the one where the free space keeps slowly going down. It started at 50 GB, but is now down to 10 GB and will keep going down from there.

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Jeff Tucker 90 Reputation points

2024-01-04T19:46:28.48+00:00

Thanks for the information. It does not seem that the Quota information covers the c:\local folder from what I can see. When we check this, it always seems that the quota is referring to the overall larger storage, and as a result always shows very low usage. But the c:\local folder has a specific size limit and this is the folder that we are running into issues with.

I will take a look at the extension mentioned in the second article. I haven't used extensions before (paranoid from a security perspective), but will take a look at the code and will see if that can help narrow down the source.

Also, just to help give more context to my original description, here is a screenshot showing the current state of this app in question. As you can see the c:\home folder is fine - no issue at all there. But the c:\local is the one where the free space keeps slowly going down. It started at 50 GB, but is now down to 10 GB and will keep going down from there.

Answer 1

SnehaAgrawal-MSFT 22,706 Moderator

@Jeff Tucker Thanks for reply! You may also refer this link- https://microsoft.github.io/AzureTipsAndTricks/blog/tip21.html

Azure Web Apps Disk Usage is an online tool that shows you the size and details of all the folders in your website.

You can see the name, size, number of files, last modified date and disk usage percentage of each folder.

The tool also displays the folders in a tree structure for easy navigation.

Let us know.

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App Service c:\local space question

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