1. Introduction VMware Virtual Machine File System (VMFS) is a high-performance clustered file system designed for storing virtual machine disks (VMDKs), configuration files, and snapshots. Despite its robustness, VMFS volumes can become corrupted due to abrupt power loss, improper VMFS upgrades, faulty storage hardware, accidental formatting, or metadata corruption.
vmfs-fuse -o ro /dev/loop0 /mnt/recovery If that fails, carve small files by known headers ( #! for VMX, KDMV for VMDK descriptor). Situation : An administrator ran vmkfstools -C vmfs5 /dev/disks/... on a datastore containing 12 production VMs. vmfs recovery
| 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-fuse -o ro /dev/loop0 /mnt/recovery If that fails,
This write-up outlines a systematic methodology for recovering data from damaged or inaccessible VMFS datastores (VMFS3, VMFS5, VMFS6) using low-level disk analysis and specialized recovery tools. | Symptom | Possible Cause | |---------|----------------| | Datastore appears as "not mounted" or "unmounted" in vSphere | Corrupt heartbeats or partition table | | VMs missing from inventory but .vmx/.vmdk files visible via CLI | Lost directory entries or corrupt file descriptors (FDs) | | Unable to power on VM: "File system specific error" | Corrupt VMFS metadata (FB, PB, or resource allocation) | | Entire LUN shows as raw or snapshot LUN | Overwritten VMFS superblock or partition table | | Deleted VMDKs still consuming space | Orphaned file blocks without FD links | 3. VMFS Metadata Structures (Recovery Essentials) Understanding key on-disk structures is critical for manual recovery: on a datastore containing 12 production VMs