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nlucero's avatar
nlucero
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1 year ago
Solved

Azure SQL Mirrored DB says "metadata tables are corrupted" when stopping then restarting replication

I created a Mirrored SQL DB in fabric that connects to a source Azure SQL DB via a service principal. I was able to get the replication up and running as expected. It began mirroring tables as expect...
data engineering
data pipeline
  • nlucero's avatar
    nlucero
    1 year ago

    I heard back from MS support. TL;DR: you need to grant VIEW PERFORMANCE DEFINITION to the managed identity fabric is using to connect to the db:

    GRANT SELECT, ALTER ANY EXTERNAL MIRROR, VIEW PERFORMANCE DEFINITION TO [User];

    The official docs only mention the need for `SELECT, ALTER ANY EXTERNAL MIRROR`.

     

    This does not fix a database that already has corrupted metadata, but it makes it so that the reproduction steps I mention in the first post do not generate a metadata corruption in the first place.

     

    I believe MS is planning to push a fix for this before the end of the month, but I don't know whether that will be just an update to the documentation or a code fix that makes the "ANY EXTERNAL MIRROR" permission sufficient.

v-ssriganesh's avatar
v-ssriganesh
Icon for Community Support rankCommunity Support
1 year ago

Hi nlucero,
Thank you for reaching out to the Microsoft Fabric Forum Community.

After thoroughly reviewing the details you provided, here’s how you can troubleshoot this without needing to restore your source database:

  • Go to the mirrored database in the Fabric portal and use the Monitor Replication section. Look for outdated timestamps or error alerts on your tables. This will confirm if replication is stalled.
  • In the Azure Portal, ensure the System Assigned Managed Identity (SAMI) for your Azure SQL logical server is enabled (check under Identity settings). Then, in Fabric, go to the mirrored database item, select Manage Permissions, and confirm the SAMI has Read and Write access.
  • Check your Azure SQL Database allows connections from Azure services (check Networking settings in the Azure Portal). If you’re using a private endpoint, you may need to set up a virtual network data gateway in Fabric to maintain a stable connection.

If the error persists, you might need to delete the mirrored database item in Fabric (this won’t affect your source database) and create a new one using the same connection details. This can often resolve metadata issues without touching the source database.

If this information is helpful, please “Accept as solution” and give a "kudos" to assist other community members in resolving similar issues more efficiently.
Thank you.

  • nlucero's avatar
    nlucero
    Icon for Advocate I rankAdvocate I
    1 year ago

    Thanks for the reply v-ssriganesh - I confirmed all of the steps above that they're not the root problem. Details below. But, in short, I am able to see the same error in the DB itself when I run

    EXEC sys.sp_change_feed_enable_db  
    @destination_type = 2;  
GO

    The full error message is: 

    Msg 22710, Level 16, State 1, Procedure sys.sp_synapse_link_enable_db_internal, Line 415 [Batch Start Line 0]
Could not update the metadata. The failure occurred when executing the command 'SetTridentLink(Value = 1)'. The error/state returned was 22697/1: 'Cannot enable fabric link on the database because the metadata tables are corrupted.'. Use the action and error to determine the cause of the failure and resubmit the request.

    So, it appears that the corrupted metadata tables are in my Azure SQL DB, independent of Fabric, and I don't know how to uncorrupt or reset them. Further, it will be a problem if the metadata tables become corrupted any time I stop replication and/or turn off my Fabric compute.

     

    More Detail:

     

    This is the view of the mirrored db in my Fabric portal. Notice that even though I previously had tables succesfully mirroring, the portal won't even list them when this error is thrown.

    I went to "manage permissions" and confirmed that my SAMI is configured with Read/Write permissions on the db. I then went into the connection definition itself, removed the credentials, and then re-added them to confirm that the connection parameters are valid and the connection is active (it is).

     

    Also, the database does allow connections from Azure services. I confirmed this. But, additionally, Fabric is having no problem connecting to that Azure SQL DB in general. I opened a new Data Factory job and successfully confirmed a connection to the same DB using the same access credentials. So, the connection itself doesn't seem to be the problem. As summarized above, I'm getting the "currupt metadata" error in the Azure SQL DB itself, even when not accessing from Fabric.

  • nlucero's avatar
    nlucero
    Icon for Advocate I rankAdvocate I
    1 year ago
    I was able to isolate the issue and the specific scenario in which it occurs:
     
    If I have a working Fabric SQL Mirror connected to a source Azure SQL DB and then I pause and then resume the Fabric compute, the Fabric mirror will report that it is still replicating but it is not. If I "Stop Replication" and then "Start Replication" on the mirror in the Fabric UI after restarting the fabric compute, then the metadata will become corrupted.
     
    However, if after restarting the compute I instead go to "Configure Replication" in the Fabric Mirrored DB, change nothing, but then "Apply Changes", it will successfully resume the replication.
     
    So the problem occurs specifically in the following sequence of events:
    1. Start with a Fabric Mirror that is successfully replicating.
    2. Stop the Fabric compute that the mirror depends on.
    3. Restart the Fabric compute
    4. "Stop Replication" on the mirror
    5. "Start Replication" on the mirror
    6. This always produces a metadata corruption in the Azure SQL DB.
     
    The problem also intermittently occurs when:
    1. Start with a Fabric Mirror that is successfully replicating.
    2. Stop the replication (keeping the fabric compute on)
    3. Start the replication again
    4. This intermittently produces a metadata corruption in the Azure SQL DB.
     
    And to avoid the metadata corruption:
    1. Start with a Fabric Mirror that is successfully replicating.
    2. Stop the Fabric compute that the mirror depends on.
    3. Restart the Fabric compute.
    4. In the Fabric Mirror UI, click "Configure replication". Change nothing, then click "Apply changes"
    5. The replication will resume as expected.
     
    Even though I now know how to avoid this issue (namely, by reconfiguring the replication instead of ever starting or stopping it), I still want to emphasize that this is a significant issue for anyone putting a production workload on Fabric because if the metadata becomes corrupted for any reason, it seems to require an Azure SQL restore from backup to resolve it. Creating a new mirrored DB on top of an Azure SQL DB that has already experienced metadata corruption does not work; it will not replicate once corrupted. So, I still need to know if there is a way to recover or reset an Azure SQL DB with corrupted replication metadata without restoring the DB from backup, because restoring from a backup means downtime and lost data.
    • v-ssriganesh's avatar
      v-ssriganesh
      Icon for Community Support rankCommunity Support
      1 year ago

      Hi nlucero,

      We sincerely regret the inconvenience this issue has caused and appreciate your detailed investigation, especially your valuable workaround using the reconfiguration approach. Given that the metadata corruption resides in the Azure SQL Database and requires a reset beyond standard portal options, we recommend raising a Microsoft support ticket for further assistance. You can create a support ticket using the link below:
      https://learn.microsoft.com/en-us/power-bi/support/create-support-ticket

      Please include the following details in your ticket to help the support team:

      • The full error message (Msg 22710... Cannot enable fabric link on the database because the metadata tables are corrupted).
      • The ArtifactId (352bb680-e0cc-4927-85d9-333b0b391c78 from your original post).
      • The specific sequence triggering the issue (e.g., compute pause > stop/start replication).
      • Your finding that reconfiguration avoids corruption.

      If this guidance helps, please “Accept as Solution” and drop a “kudos” to make it easier for other community members to find. We hope this resolves the issue for you.

      Thank you.

      • WLY168's avatar
        WLY168
        Icon for Advocate I rankAdvocate I
        1 year ago

        Just to confirm I have experienced the exact same problem and managed to replicate the scenario using a Fabric Trial. Based on this risk we would not consider talking the technology to production. A simple start and stop of the replication should not have such a high impact on the source. For platform as a managed service this is truly alarming.

        My steps were simply to:

        1. Stop the fabric mirror

        2. Start the fabric mirror


        Since it was a Fabric Trial I could find no way to pause the capacity. 

         

        DBCC and using DMV's could not identify any problems / corruptions in the source Azure SQL Database. Dynamic Management Views are probably fruitless since the link itself cannot be established.

        The exact same error : "Code: SqlChangeFeedError, Type: UserError, Message: Cannot enable fabric link on the database because the metadata tables are corrupted. ArtifactId: e21c6419-bdca-497c-8f00-96ad0c262608"

         

        Destroying the mirror and trying to recreate it from scratch has absolutely no effect on the outcome ... which re-inforces the suspicion that something fundamentally changes in the source database.