Deduplication volume repair help needed

Question

Hi guys
We just had an unclean shutdown, and now one of our deduplicated volumes is throwing chunk store corruption warnings. I’m worried this could escalate into data loss if we don’t act quickly. Could any of the engineers advise on the proper supported repair process here? Specifically, should we be looking at DDPEval or scrubbing as the first step before things get worse ?

Answer 1

Welcome to Microsoft Q&A Forum! 

Based on your description, I would recommend starting with Integrity Scrubbing, not DDPEval. Integrity Scrubbing is the Data Deduplication maintenance job specifically designed to detect corruption within the chunk store and attempt recovery when redundant copies of the data are available. The Scrubbing job identifies chunk store corruption caused by disk failures or bad sectors and repairs recoverable corruption when possible.

In contrast, DDPEval.exe (Deduplication Evaluation Tool) is intended to estimate potential storage savings before enabling Data Deduplication. It is an assessment tool and is not intended to repair or recover chunk store corruption. For a deduplicated volume that began reporting chunk store corruption warnings after an unclean shutdown, I recommend the following:

• Review the Data Deduplication Operational and System event logs to identify the specific corruption events being reported.
• Run an Integrity Scrubbing job. If the logged events indicate more severe corruption, consider running Full/Deep Scrubbing.
• Verify the results after the job completes and confirm that no additional corruption events are generated
• Ensure you have a current backup before pursuing any further recovery actions.

So in your case, Scrubbing is the appropriate first step for investigating and repairing recoverable chunk store corruption, while DDPEval is designed for evaluating deduplication savings and is not a repair utility.

For additional information, please refer to:

Understanding Data Deduplication | Microsoft Learn

Troubleshoot Windows Server Data Deduplication - Windows Server | Microsoft Learn

I hope this information helps clarify the behavior and points you in the right direction. If this answer was helpful, please Accept the Answer.

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