Recover Vmfs Metadata -

VMFS version: 6.81 Volume UUID: 4a5b3c2d-... Number of heartbeats: 3 If it fails with No VMFS filesystem found , metadata is corrupt or missing. Use dd and hdparm to check if basic partition table is readable:

esxcfg-volume -l # List snapshot volumes esxcfg-volume -r <vol_name> # Resignature (keeps data) VMFS6 stores redundant copies of critical metadata structures. You can manually copy a backup superblock:

# Find backup superblock locations (example for VMFS6) # Primary at LBA 1, backup at LBA 2048, 4096, etc. dd if=/vmfs/devices/disks/naa.6000... of=/tmp/backup_superblock bs=512 count=1 skip=2048 # Restore primary dd if=/tmp/backup_superblock of=/vmfs/devices/disks/naa.6000... bs=512 count=1 seek=1 Incorrect offsets can destroy data. Only attempt if you have exact documentation for your VMFS version. 3.3 Third-Party Recovery Tools (Recommended for Critical Data) Several commercial tools specialize in VMFS metadata reconstruction. They work by scanning the raw device for file signatures and rebuilding the allocation map. recover vmfs metadata

dd if=/vmfs/devices/disks/naa.6000... bs=512 count=1 | hexdump -C Look for “VMFS” ASCII signature at offset 0x200. If present but higher-level structures corrupt, recovery is possible. Recovery options depend on whether you have backups, ESXi’s built-in repair utilities, or need third-party tools. 3.1 First Line: ESXi Built-in Commands A. vmfs-fs-rescue (VMFS3/5 only – deprecated in newer versions) For older environments, this utility attempts to rebuild the FDC table from residual metadata.

vmfs-fs-rescue /vmfs/devices/disks/naa.6000...:1 This creates a lost+found directory with recoverable files. It does not preserve original folder structure but may recover VMDK and VMX files. VMFS does not have an fsck like ext4. Instead, VMware relies on journal replay on mount. To force replay: VMFS version: 6

# List all partitions on a device (e.g., naa.6000...) partedUtil get /vmfs/devices/disks/naa.6000... fdisk -l /vmfs/devices/disks/naa.6000... Attempt to probe filesystem vmfs-fs-probe /vmfs/devices/disks/naa.6000...:1 View kernel VMFS errors tail -100 /var/log/vmkernel.log | grep -i vmfs

Expected output from vmfs-fs-probe if metadata intact: You can manually copy a backup superblock: #

# Unmount if mounted vmkfstools -V /vmfs/devices/disks/naa.6000...:1 # Remount to replay journal esxcfg-volume -M <datastore_name> If corruption is due to ESXi detecting a duplicate UUID, resignaturing preserves metadata but changes datastore identity: