Use vSphere On-disk Metadata Analyzer (VOMA) to identify and fix incidents of metadata corruption that affect file systems or underlying logical volumes.


You can check metadata consistency when you experience problems with a VMFS datastore or a virtual flash resource. For example, perform a metadata check if one of the following occurs:
  • You experience storage outages.
  • After you rebuild RAID or perform a disk replacement.
  • You see metadata errors in the vmkernel.log file similar to the following:
    cpu11:268057)WARNING: HBX: 599: Volume 50fd60a3-3aae1ae2-3347-0017a4770402 ("<Datastore_name>") may be damaged on disk. Corrupt heartbeat detected at offset 3305472: [HB state 0 offset 6052837899185946624 gen 15439450 stampUS 5 $
  • You are unable to access files on a VMFS.
  • You see corruption being reported for a datastore in events tabs of vCenter Server.


To check metadata consistency, run VOMA from the CLI of an ESXi host. VOMA can be used to check and fix minor inconsistency issues for a VMFS datastore or logical volumes that back the VMFS datastore.

VOMA can check and fix the following items.

Table 1. VOMA Functions
VOMA Functions Description
Metadata check and fix Examples of metadata check and fix include, but are not limited to, the following:
  • Validation of VMFS volume header for basic metadata consistency.
  • Checking consistency of VMFS resource files (system file).
  • Checking the pathname and connectivity of all files.
Affinity metadata check and fix

To enable the affinity check for VMFS6, use the -a|--affinityChk option.

Several examples of affinity metadata check and fix include the following:
  • Affinity flags in resource types and FS3_ResFileMetadata.
  • Validation of affinity flags in SFB RC meta (FS3_ResourceClusterMDVMFS6).
  • Validation of all entries in the affinityInfo entries in rcMeta of RC, including the overflow key, to make sure no invalid entries exist. Checking for missing entries.
Directory validation VOMA can detect and correct the following errors:
  • Directory hash block corruption.
  • Alloc map corruption.
  • Link blocks corruptions.
  • Directory entry block corruptions.

Based on the nature of the corruption, VOMA can either fix only the corrupted entries or fully reconstruct the hash block, alloc map blocks and link blocks.

Lost and found files

During a filesystem check, VOMA can find files that are not referenced anywhere in the filesystem. These orphaned files are valid and complete, but do not have a name or directory entry on the system.

If VOMA encounters orphaned files during scanning, it creates a directory named lost+found at the root of the volume to store the orphaned files. The names of the files use the Filesequence-number format.

Command options that the VOMA tool takes include the following.

Table 2. VOMA Command Options
Command Option Description
-m|--module The modules to run include the following:
vmfs If you do not specify the name of the module, this option is used by default.

You can check the VMFS file systems and the file systems that back virtual flash resources. If you specify this module, minimal checks are performed for LVM as well.

lvm Check logical volumes that back the VMFS datastores.
ptbl Check and validate VMFS partitions, such as MBR or GPT. If no partition exists, determine whether partitions should exist.
-f|--func Functions to be performed include the following:
query List functions supported by module.
check Check for errors.
fix Check and fix errors.
dump Collect metadata dump.
-a|--affinityChk Include affinity related check and fix for VMFS6.
-d|--device Device or disk to be inspected. Make sure to provide the absolute path to the device partition backing the VMFS datastore. For example, /vmfs/devices/disks/naa.00000000000000000000000000:1.
-s|--logfile Specify the log file to output the results.
-x|--extractDump Extract the collected dump using VOMA.
-D|--dumpfile Dump file to save the collected metadata dump.
-v|--version Display the version of VOMA.
-h|--help Display the help message for the VOMA command.


voma -m vmfs -f check -d /vmfs/devices/disks/naa.xxxx:x

voma -m vmfs -f dump -d /vmfs/devices/disks/naa.xxxx:x -D dumpfilename