This case study documents the successful forensic recovery of a 60 GB MongoDB 4.x database following a catastrophic server array (RAID) malfunction. By manually extracting data from orphaned collection files, the AS Data Recovery team bypassed the missing metadata to achieve a 100% restoration.
Client & Data Information
- Client Name: Confidential
- Data Type: MongoDB 4.x (WiredTiger Storage Engine)
- Data Capacity: 60 GB
- Primary Issue: Server RAID Array Malfunction / Missing Metadata
Incident Summary
The client’s production server suffered a hardware array failure. While the physical disks were stabilized, the resulting file system corruption led to the total loss of MongoDB’s metadata information. Specifically, the files that act as the database’s internal “table of contents” were missing or zeroed out. Without this metadata, the MongoDB service was unable to map logical collections to their physical counterparts, causing a fatal startup failure.
Technical Analysis
Upon forensic analysis of the recovered 60 GB data directory, AS Data Recovery engineers identified:
- Missing Control Files: The WiredTiger.wt and size.wt files were absent, meaning the database engine had no record of which collections existed or where they were stored within the storage layer.
- Physical Data Persistence: Despite the missing “map,” the individual .wt files containing the raw BSON (Binary JSON) documents remained physically present on the disks.
- RAID Inconsistency: Minor striping errors from the array malfunction had corrupted some file headers, requiring manual correction before extraction could begin.
Recovery Solution
The recovery strategy utilized Low-Level Collection Carving. Since the MongoDB service could not initialize the data directory, our engineers bypassed the service layer entirely. Using proprietary forensic tools, we performed a deep-sector scan of the physical collection files. By identifying the internal B-tree structures of the WiredTiger files, we were able to extract the raw BSON records and reassemble them into a new, functional database.
Recovery Process
- Forensic RAID Reconstruction: Stabilized the server array and created a bit-for-bit clone of the storage volume to prevent secondary data loss.
- Orphaned File Mapping: Scanned the 60 GB directory to identify all physical .wt files. Our tools analyzed the internal data signatures to determine which collections they originally belonged to.
- WiredTiger Page Parsing: Directly accessed the raw pages within the physical collection files, bypassing the need for the central WiredTiger.wt metadata file.
- Data Extraction & Migration: Extracted the records into a clean JSON format and re-imported them into a freshly initialized MongoDB 4.x instance.
- Integrity Validation: The client performed a final verification of the record counts and document structures, confirming a 100% recovery success rate.
Recovery Results
- Recovery Integrity: 100% (All documents and collections restored)
- Recovered Volume: 60 GB
- System Status: Database fully operational on a newly configured RAID array.
- Total Recovery Time: 4 Hours
Expert Reminder from AS Data Recovery: RAID malfunctions can lead to “silent corruption” where files look healthy but metadata is missing. Do not attempt to ‘re-init’ the database, as this will overwrite your existing data files with empty templates. Contact AS Data Recovery professionals immediately for forensic-level database extraction. We guarantee recovery for specific failures regardless of the database size.