If your Veeam Backup files have been damaged due to storage media failure or malware activity, your first and best step is to contact Veeam Technical Support for assistance.
I am a Data Recovery specialist and am not affiliated with Veeam. The following information is based on my personal experience recovering data from damaged backup files in a professional DR laboratory, specifically dealing with media failures and ransomware-induced corruption.
Terminology used:
- Header: The first 4KB of the file.
- SSS0 / SSS1 (Snapshot Slots): Contain archive metadata (parameter groups, Metabank tables with addresses and sizes, and CRC for integrity verification).
- Metabank: Contains the metadata required to navigate the backup file.
The metadata describing data block placement forms tree-like structures that build an abstract object map. This map is then associated with a map of physically stored blocks. This separation of maps is precisely what enables Veeam's deduplication mechanism.
Q: The Header (first 4KB) is damaged.
A: This is the easiest scenario. Often, simply transplanting a valid header from a healthy file of the same version and block size is sufficient. In some cases, minor additional adjustments may be required. Success prognosis: ~100%.
Q: SSS0 and SSS1 are damaged or missing.
A: This requires scanning the entire VBK/VIB/VRB file space for Metabanks. Based on the scan results, you must compile lists of Metabanks for both the primary (0) and secondary (1) copies, reconstruct the Snapshot Slots, populate the Snapshot Slot Descriptions, and write the bank tables with recalculated CRCs for both the banks and the Slots themselves. Success prognosis: Close to 100%.
Q: Both copies of the Metabanks are partially corrupted at various offsets.
A: This requires a page-by-page analysis of each damaged Metabank. Often, a complete, healthy copy can be synthesized by merging the two damaged copies. This requires advanced scanning to locate metadata fragments based on known structure types and verify their integrity. Success prognosis: Close to 100% if no pages are missing in the reconstructed object. If pages are missing, a full metadata analysis is required (directory records, tree reconstruction, physical block map assessment) to calculate the exact data loss percentage.
Q: Directories containing saved object names and links to root metadata tree structures are damaged.
A: Requires a full metadata scan and tree reconstruction. If the trees themselves are intact, the success prognosis is close to 100%. A secondary challenge is stitching incremental chains, as this requires accurately mapping the recovered unnamed objects to objects with valid name records.
Q: Certain Metabanks are entirely missing from the Metabank chain.
A: This is a severe scenario requiring full metadata analysis (directory records, tree reconstruction, physical block map assessment) to calculate the data loss percentage. Success heavily depends on the scale of the loss. Without root tree structures, you may only recover block groups of varying granularity based on the integrity of the surviving branches. Reconstructing large objects then requires building a "virtual translator" to determine block ownership. If large branches survive, the chances of success remain reasonably high.
Q: Loss of the physical object map.
A: A complex task requiring a full file scan to identify compressed block offsets, compression types (most commonly LZ4), compressed block sizes, and alignment padding. After building the physical block map and calculating digests, one can attempt to associate this physical map with the logical block numbers in the metadata trees.
Q: Complete loss of all Metabanks.
A: The worst-case scenario, where 100% of Metabank pages are destroyed. Object maps cannot be built due to the total absence of metadata. The only path is a full file scan to identify surviving data blocks. Two approaches remain:
- Sequential unpacking: Unpacking all compressed blocks yields raw material suitable for carving small files (typically smaller than the block size).
- Virtual translator reconstruction: Extracting all compressed blocks and attempting to build a mapping layer. This involves searching for known file system and file type signatures to deduce the role of blocks within reconstructed objects. This is a highly resource-intensive method and is generally effective only for objects containing many small files. Reconstructing large files this way remains a topic of ongoing discussion and research within the professional Data Recovery community.
