VMFS Metadata Corruption in vSphere 5.1 and Newer: Taking The Lead in The Battle With VOMA

VMFS corruption is one of disasters which happening you might lose both service and data. vSphere On-Disk Metadata Analyzer (VOMA) would help you to fix some issues on VMFS and repair metadata.

You should have backup from virtual machines and data in any environment but sometimes, backup won’t help to recover services and you have to resolve the problem without restoring backup.

Also restoring backup of data is equal to data lost. At least, service’s data will be lost between failure and last successful backup session.

vSphere On-Disk Metadata Analyzer (VOMA) introduced in vSphere 5.1 and available on newer version as well.

vSphere On-disk Metadata Analyzer (VOMA)

vSphere On-disk Metadata Analyzer (VOMA)

VOMA, introduced by VMware, is a command-line utility designed to analyze and repair inconsistencies or corruptions in vSphere on-disk metadata. It provides administrators with a powerful tool to detect and resolve potential issues that may impact the stability and performance of their virtual environment.

Before this update if you experienced any metadata error or corruption in a VMFS6 datastore you needed to collect (dump) the datastore metadata and upload the dump file to a created VMware support case and get the updated dump to be imported back into your datastore for any chance to recover your machines from these errors.

VMware support analyzes the uploaded file and runs a script to repair the errors (if can be repaired) then will assist to re-apply the metadata to your volume.

VOMA, Key Features and Capabilities

vSphere On-disk Metadata Analyzer (VOMA) has four key features and capabilities:

  • Comprehensive Analysis
  • Proactive Detection
  • Repair and Recovery
  • Command-Line Interface

Comprehensive Analysis

VOMA performs a comprehensive examination of vSphere on-disk metadata, including the configuration files, VMFS datastores, and virtual machine files. It checks for inconsistencies, misconfigurations, or corruptions that might lead to data integrity problems.

Proactive Detection

The proactive nature of VOMA allows administrators to identify potential issues before they manifest as significant problems. By running periodic scans, system administrators can mitigate risks and ensure the smooth operation of their vSphere environment.

Repair and Recovery

In addition to detecting inconsistencies, VOMA can also repair minor corruptions in the metadata. By addressing these issues promptly, VOMA helps safeguard against data loss and minimizes the impact on critical workloads.

Command-Line Interface

VOMA operates through a command-line interface (CLI), enabling administrators to integrate it seamlessly into their automation and scripting workflows. This CLI-driven approach ensures flexibility and scalability, especially in large-scale vSphere deployments.

When Should Use vSphere On-disk Metadata Analyzer (VOMA)?

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.
  • Reports are indicating corruption in a datastore in the events tabs of vCenter Server.

VMFS is a journaling file system where it keeps track of changes not committed to the disk yet. These journals are later replayed by the hosts.

The journal/HB block leaks happen on VMFS Filesystem in the case of storage connectivity problems while closing volume.


VMware vSphere On-Disk Metadata Analyzer (VOMA) is an indispensable tool for vSphere administrators, allowing them to proactively detect, analyze, and repair metadata inconsistencies in their virtual infrastructure. With its comprehensive analysis, proactive detection, and repair capabilities, VOMA ensures the stability, reliability, and data integrity of vSphere deployments. By leveraging this powerful tool, organizations can optimize their vSphere environment, minimize downtime, and confidently operate their virtual infrastructure.

Further Reading

Lockdown Mode in VMware vSphere, Not Easy to Decide!

Optimizing Data Protection: Unleashing the Power of Database Backup Best Practices in Virtualization Platforms

I/O Block Size Best Practice on EMC All Flash/Hybrid Flash Array and Linux (Physical And Virtual)

External Links

Checking Metadata Consistency with VOMA

Davoud Teimouri

Professional blogger, vExpert 2015/2016/2017/2018/2019/2020/2021/2022/2023, vExpert NSX, vExpert PRO, vExpert Security, vExpert EUC, VCA, MCITP. This blog is started with simple posts and now, it has large following readers.

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