Vmfs Recovery May 2026

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:

Example (pseudo‑script logic):

sgrep -b 'VMFS5' vmfs_disk.dd FDs start with a known pattern (e.g., FD 00 00 01 for VMFS5). Scan the entire disk: vmfs recovery

fd = read_fd(fd_number) for each block_pointer in fd.fbt: dd if=vmfs_disk.dd of=recovered_flat.vmdk \ bs=<vmfs_block_size> skip=<block_pointer> count=1 seek=<output_offset> These are stored in metadata heaps. Use vmfs-fuse (from vmfs-tools) in read‑only mode if superblock is partially valid: Scan the entire disk: fd = read_fd(fd_number) for

| Tool | Best for | |------|----------| | | VMFS3/5/6, deleted VMDKs, RAID reconstruction | | R‑Studio | VMFS datastores with partition table loss | | SysTools VMFS Recovery | Simple file extraction from healthy metadata | | vmfs-tools (open source) | Manual CLI recovery, limited to clean FS | limited to clean FS |