dcfldd if=/dev/sdX of=vmfs_disk.dd hash=sha256 hashlog=hash.txt bs=1M conv=noerror,sync # Or using ddrescue for failing drives ddrescue -f /dev/sdX vmfs_disk.dd vmfs_mapfile Commercial tools are often the fastest path:
| Structure | Purpose | Location (LBA offset) | |-----------|---------|------------------------| | | FS UUID, version, block size, heartbeat region | LBA 128 (VMFS5/6), LBA 1 (VMFS3) | | File Descriptor (FD) | Inode-like entry pointing to FB/PC regions | Varies – part of file system heap | | FBC (File Block Map) | Physical block pointers for file data | Allocated from metadata heap | | Heartbeat Region | LUN ownership & cluster health | LBA 0x1000 – 0x2000 | | Resource Allocation (RA) | Free block tracking | Located in metadata partition | | Directory Entries (DirEntry) | Filename ↔ FD mapping | Inside .vmdk directory or root | Recovery principle : If superblock is intact, the FS can be logically remounted. If not, you must scan for FDs and rebuild the block map. 4. Step-by-Step Recovery Workflow 4.1 Initial Assessment (Non‑destructive) # Identify VMFS partitions (Linux with vmfs-tools or esxcli) esxcli storage vmfs snapshot list partedUtil get /dev/disks/naa.600... | grep vmfs Check if superblock is readable dd if=/dev/sdX bs=512 skip=128 count=1 | hexdump -C | head -20 Look for magic string "VMFS" or "VMFS5"/"VMFS6" 4.2 Full Disk Imaging (Mandatory) Always work on a forensic image to preserve evidence: vmfs recovery
sgrep -b 'VMFS5' vmfs_disk.dd FDs start with a known pattern (e.g., FD 00 00 01 for VMFS5). Scan the entire disk: dcfldd if=/dev/sdX of=vmfs_disk
# Check VMDK descriptor consistency vmkfstools -Q recovered_vm.vmdk dd if=recovered_flat.vmdk bs=1M count=1 | hexdump -C Attempt to mount or clone vmkfstools -i recovered_flat.vmdk -d thin verified.vmdk Step-by-Step Recovery Workflow 4