Azure File Sync is not working bi-directional

Question

Azure File Sync is not working bi-directional

ASY ASY 25

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I have a third party application which runs on an on-premises windows server. This application generates.xml files and places them to a folder on the same server.

And I have an Azure Function to pick up those files, process them and move to an archive folder on the same on-premises server.

Folder path where xml files are generated: D:\XMLFiles\

The archive folder my azure function writes back: D:\XMLFiles\XMLArchive\

The requirement is to be able to detect when a new file is created on the server (D:\ XMLFiles) and pick for my Azure function processing on a near real time basis. And once the file is processed. Move it to archive (D:\XMLFiles\XMLArchive).

I've followed the document to deploy Azure File Sync

1- I've installed Azure File Sync agent on the on premises server.

2- I've created an Azure Storage Sync Service in Azure Portal.

3- I've registered my server with Azure Storage Sync Service

4- I've created an Azure Storage account with a File Share.

5- I've created a Sync Group under Azure Storage Sync Service:

 - Cloud Endpoint: Azure File Share

 - Server Endpoint: my on premises server.

I've developed an azure function periodically scan the Azure File Share that is set up above.

When xml files are generated on my windows server, I can see that it is replicated in my Azure File Share near real time. So this works good.

But when my function writes files to archive from Azure end (through Azure File Share) I don't see those files are replicated to the Windows Server.

Is this the normal behavior of Azure File Sync Agent?

ASY ASY 25 Reputation points

2025-06-17T09:52:36.4966667+00:00

Hi Nandamuri Pranay Teja,

Thanks for your prompt and detailed answer on my question.

Just a correction on my initial post the drive was C instead of D. But all paths are correct.

And I can confirm that the folder structures are not modified during or after the setup.

And this is my test flow:

Step1: I've placed two xml file under C:\xmlfiles folder and waiting for agent to sync back to azure.

Step2: I check Azure File share mapped as cloud end. I can see both xml files reflected.

Step3: My function (on a timer trigger) picks the files from File Share. And moves them from

/myfileshare/ location to /myfileshare/xmlarchive/ on Azure File share.

After this step I expect two things happen.

1-See the xml files deleted from C:\xmlfiles folder.

2- See the files moved to C:\xmlfiles\xmlarchive subfolder.

Unfortunately this part is not happening.

Also I tried to check Windows event logs. But could not find the Services Logs -> Microsoft -> FileSync -> Sync category in logs. But nothing extraordinary in Operational category.

Also I've googled similar questions found that some people mention, the purpose of this service is to sync files from server to cloud near real time. But when files are added / changed on cloud they get reflected to server around 24 hours of time. Not immediately. Is it possible to clarify this?

Please check this comment below:

https://www.reddit.com/r/AZURE/comments/1b1xxaz/comment/ksjcn8c/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

https://stackoverflow.com/a/61845913/1131784

May be I am using he service on the wrong purpose.

Thanks.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-17T10:32:58.2266667+00:00
Hello ASY ASY

Thank you for the detailed clarification and the screenshots!

I understand that all paths now refer to C:\xmlfiles\ and C:\xmlfiles\xmlarchive\. After your Azure Function moves files from /myfileshare/ to /myfileshare/xmlarchive/, trigger the following PowerShell command:

Invoke-AzStorageSyncChangeDetection ` -ResourceGroupName "yourResourceGroup" ` -StorageSyncServiceName "yourStorageSyncService" ` -SyncGroupName "xmlfilesgroup" ` -CloudEndpointName "xmlfiles" ` -DirectoryPath "xmlarchive" ` -Recursive ` -AsJob ` -PassThru

Replace your Resource Group and Storage Sync Service with your actual resource names. SyncGroupName is xmlfilesgroup (from your screenshot). CloudEndpointName is xmlfiles (the name of your file share). DirectoryPath is xmlarchive (relative path to the archive folder in the file share).

Now Integrate this into your Azure Function workflow: Create a secondary Azure Function or Logic App to run this command after the file is moved. Alternatively, use Azure Automation Runbooks to execute the command.

The change detection job will scan the xmlarchive folder on the Azure File Share and detect the moved files. Azure File Sync will then propagate the changes to the server endpoint:

Delete the files from C:\xmlfiles (since they were deleted from /myfileshare/).

Add the files to C:\xmlfiles\xmlarchive (since they were moved to /myfileshare/xmlarchive/).

Note: the changes take few minutes

Hope the above answer helps! Please let us know do you have any further queries.

Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-18T04:07:53.0833333+00:00

Hello ASY ASY

Just checking in to see if the provided answer helped. If this answers your query, do click "Up-Vote” for the same, which might be beneficial to other community members reading this thread. And, if you have any further queries do let us know.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-19T01:21:24.7566667+00:00

Hello ASY ASY

I wanted to follow up and see if the given answer was helpful. If this resolves your issue, please click "Accept the answer" for it, which could help other community members who read this thread. And, if you have any more questions, please let us know.
ASY ASY 25 Reputation points

2025-06-24T09:50:59.13+00:00

Hi Nandamuri,

Apologies for my late reply and thanks for your detailed answer.

Yes I tried the command and it helped me to to sync from cloud to VM direction.

However I was expecting Azure File Sync to provide a near real time sync for both directions without any extra steps from my end like executing a PS command.

So, having to trigger from cloud and waiting for around 2-3 minutes would not solve my individual requirement.

I moved to another solution option (ADF with SHIR). But good learning for where the Azure File Sync best fits.

Thanks.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-24T18:33:26.5633333+00:00

Hello ASY ASY

Thank you so much for the kind response! And thank you for reaching me out back

Yes, ASY ASY Azure File Sync's primary strength lies in its near real-time server-to-cloud synchronization and its ability to act as a cache (cloud tiering) for on-premises users. However, for cloud-initiated changes syncing back down to the server, it relies on polling, which introduces a delay (up to 24 hours, or often 1-2 hours in practice, but definitely not "near real-time"). This design choice optimizes for cost and scalability in typical file server extension scenarios, not immediate bi-directional workflow automation.

Your decision to move to Azure Data Factory (ADF) with a Self-Hosted Integration Runtime (SHIR) is indeed the correct and most robust solution for your specific requirement of near real-time, event-driven, bi-directional file processing and movement between Azure and you're on-premises server.

If the issue is resolved I request, you to kindly "Accept the answer” this can be beneficial to other community members.

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ASY ASY 25 Reputation points

2025-06-17T09:52:36.4966667+00:00

Hi Nandamuri Pranay Teja,

Thanks for your prompt and detailed answer on my question.

Just a correction on my initial post the drive was C instead of D. But all paths are correct.

And I can confirm that the folder structures are not modified during or after the setup.

And this is my test flow:

Step1: I've placed two xml file under C:\xmlfiles folder and waiting for agent to sync back to azure.

Step2: I check Azure File share mapped as cloud end. I can see both xml files reflected.

Step3: My function (on a timer trigger) picks the files from File Share. And moves them from

/myfileshare/ location to /myfileshare/xmlarchive/ on Azure File share.

After this step I expect two things happen.

1-See the xml files deleted from C:\xmlfiles folder.

2- See the files moved to C:\xmlfiles\xmlarchive subfolder.

Unfortunately this part is not happening.

Also I tried to check Windows event logs. But could not find the Services Logs -> Microsoft -> FileSync -> Sync category in logs. But nothing extraordinary in Operational category.

Also I've googled similar questions found that some people mention, the purpose of this service is to sync files from server to cloud near real time. But when files are added / changed on cloud they get reflected to server around 24 hours of time. Not immediately. Is it possible to clarify this?

Please check this comment below:

https://www.reddit.com/r/AZURE/comments/1b1xxaz/comment/ksjcn8c/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button

https://stackoverflow.com/a/61845913/1131784

May be I am using he service on the wrong purpose.

Thanks.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-17T10:32:58.2266667+00:00

Hello ASY ASY

Thank you for the detailed clarification and the screenshots!

I understand that all paths now refer to C:\xmlfiles\ and C:\xmlfiles\xmlarchive\. After your Azure Function moves files from /myfileshare/ to /myfileshare/xmlarchive/, trigger the following PowerShell command:

Invoke-AzStorageSyncChangeDetection ` -ResourceGroupName "yourResourceGroup" ` -StorageSyncServiceName "yourStorageSyncService" ` -SyncGroupName "xmlfilesgroup" ` -CloudEndpointName "xmlfiles" ` -DirectoryPath "xmlarchive" ` -Recursive ` -AsJob ` -PassThru

Replace your Resource Group and Storage Sync Service with your actual resource names. SyncGroupName is xmlfilesgroup (from your screenshot). CloudEndpointName is xmlfiles (the name of your file share). DirectoryPath is xmlarchive (relative path to the archive folder in the file share).

Now Integrate this into your Azure Function workflow: Create a secondary Azure Function or Logic App to run this command after the file is moved. Alternatively, use Azure Automation Runbooks to execute the command.

The change detection job will scan the xmlarchive folder on the Azure File Share and detect the moved files. Azure File Sync will then propagate the changes to the server endpoint:

Delete the files from C:\xmlfiles (since they were deleted from /myfileshare/).

Add the files to C:\xmlfiles\xmlarchive (since they were moved to /myfileshare/xmlarchive/).

Note: the changes take few minutes

Hope the above answer helps! Please let us know do you have any further queries.

Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-18T04:07:53.0833333+00:00

Hello ASY ASY

Just checking in to see if the provided answer helped. If this answers your query, do click "Up-Vote” for the same, which might be beneficial to other community members reading this thread. And, if you have any further queries do let us know.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-19T01:21:24.7566667+00:00

Hello ASY ASY

I wanted to follow up and see if the given answer was helpful. If this resolves your issue, please click "Accept the answer" for it, which could help other community members who read this thread. And, if you have any more questions, please let us know.
ASY ASY 25 Reputation points

2025-06-24T09:50:59.13+00:00

Hi Nandamuri,

Apologies for my late reply and thanks for your detailed answer.

Yes I tried the command and it helped me to to sync from cloud to VM direction.

However I was expecting Azure File Sync to provide a near real time sync for both directions without any extra steps from my end like executing a PS command.

So, having to trigger from cloud and waiting for around 2-3 minutes would not solve my individual requirement.

I moved to another solution option (ADF with SHIR). But good learning for where the Azure File Sync best fits.

Thanks.
Nandamuri Pranay Teja 3,610 Reputation points Microsoft External Staff Moderator

2025-06-24T18:33:26.5633333+00:00

Hello ASY ASY

Thank you so much for the kind response! And thank you for reaching me out back

Yes, ASY ASY Azure File Sync's primary strength lies in its near real-time server-to-cloud synchronization and its ability to act as a cache (cloud tiering) for on-premises users. However, for cloud-initiated changes syncing back down to the server, it relies on polling, which introduces a delay (up to 24 hours, or often 1-2 hours in practice, but definitely not "near real-time"). This design choice optimizes for cost and scalability in typical file server extension scenarios, not immediate bi-directional workflow automation.

Your decision to move to Azure Data Factory (ADF) with a Self-Hosted Integration Runtime (SHIR) is indeed the correct and most robust solution for your specific requirement of near real-time, event-driven, bi-directional file processing and movement between Azure and you're on-premises server.

If the issue is resolved I request, you to kindly "Accept the answer” this can be beneficial to other community members.

Answer 1

Hello ASY ASY

Please be informed that that the D:\XMLFiles\XMLArchive\ folder on your on-premises server is not correctly considered part of the Server Endpoint's synchronized scope. Because when you configure a Server Endpoint, you define a specific local path on your server that Azure File Sync will monitor and synchronize. All subdirectories and files within that specified path should be included in the sync.

Go to your Azure Storage Sync Service and Navigate to your Sync Group.
Under the "Server endpoints" section, click on the entry for your on-premises server.

Look at the "Path" field.

Is it precisely D:\XMLFiles? If it is, then D:\XMLFiles\XMLArchive\ is a subdirectory, and it should sync. Is it D:\ or some other parent folder, and XMLFiles is a subfolder? If so, then D:\XMLFiles\XMLArchive\ should still be covered.
Is there any chance the Server Endpoint was configured only for D:\XMLFiles and the XMLArchive folder was later created outside its perceived scope, or there's a misunderstanding of how subdirectories are handled? (Unlikely if it's a direct subfolder, but worth confirming).

Post which Examine Azure File Sync Agent Logs on the On-Premises Server:

On your Windows Server, open Event Viewer.
Navigate to Applications and Services Logs -> Microsoft -> FileSync -> Sync.
Look for any warning or error events related to download or synchronization. These logs will tell you if the agent is even attempting to download changes for that archive folder and why it might be failing.

Why it's Not Normal Behavior and What to Expect?

If D:\XMLFiles\XMLArchive\ is indeed a subfolder of your configured Server Endpoint path (e.g., D:\XMLFiles), then any files placed into /myfileshare/XMLArchive/ via your Azure Function should absolutely sync down to D:\XMLFiles\XMLArchive\ on your server.

Confirm it encompasses the D:\XMLFiles\XMLArchive\ directory. diagnosing why the download isn't happening. Look for specific error messages or warnings in the Sync event logs.
If all configurations look correct and logs don't immediately reveal a clear issue, consider restarting the Azure File Sync Agent service on your on-premises server to force a rescan. (Search for "Services" -> find "Azure File Sync Agent" -> Restart).

References:

Hope the above answer helps! Please let us know do you have any further queries.

Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

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Azure File Sync is not working bi-directional

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