VM Problem: Taking a Quiesced Snapshot Fails

Title: VMware VM Problem: Taking a Quiesced Snapshot Fails

Taking a quiesced VMWare snapshot of a VM fails.

A VM generating heavy I/O workload might encounter issues when quiescing before a snapshot operation.

Quiescing can be done by using the following technologies:

• Microsoft Volume Shadow Copy Service (VSS)

• VMware Tools SYNC driver

As an initial check, you verify that you can create a manual, nonquiesced snapshot by using Snapshot Manager.

VMware products might require file systems in a guest OS to be quiesced before taking snapshots for the purposes of backup and data integrity. Services that are known to generate heavy I/O workload include Exchange, Active Directory, LDAP, and MS-SQL. The quiescing operation can be done by Microsoft Volume Shadow Copy Service (VSS). Microsoft provides VSS in its operating systems since Windows Server 2003. Before verifying a VSS quiescing issue, ensure that you can create a manual nonquiesced snapshot with the Snapshot Manager in the vSphere Client. The quiescing operation can also be done with an optional VMware Tools component called the SYNC driver.



Snapshot functionality in VMware is crucial for preserving the state of virtual machines (VMs) and ensuring data integrity. However, encountering issues while taking a quiesced snapshot can be a concern. This article addresses the common problem of failed quiesced snapshots in VMware VMs and provides guidance on investigation and resolution.

Understanding Quiesced Snapshots:

A quiesced snapshot is a point-in-time image of a VM that is taken while the VM is in a consistent state. This is achieved by temporarily pausing disk I/O and creating a snapshot to capture a clean image, minimizing the risk of data corruption.

Common Issues:

  1. VMware Tools Version Mismatch: Ensure that the installed version of VMware Tools matches the ESXi host version. A mismatch can lead to compatibility issues affecting snapshot operations.
  2. VMware Tools Not Installed or Outdated: Confirm that VMware Tools is installed on the VM and is up-to-date. Outdated or missing tools may result in snapshot failures.
  3. Insufficient Disk Space: Check available disk space on the datastore where the VM’s files are stored. Insufficient space can prevent the creation of snapshots.
  4. VM Configuration Issues: Verify the VM’s configuration settings, especially those related to disk controllers and virtual hardware. Misconfigurations can interfere with snapshot creation.

Investigation Steps:

  1. Review VMware Tools Status: Check the status of VMware Tools on the VM. Ensure it is running and properly configured. Restarting VMware Tools may resolve transient issues.
  2. Examine Disk Space: Evaluate the available disk space on the datastore. If space is low, consider freeing up storage or expanding the datastore.
  3. Update VMware Tools: If VMware Tools is outdated, upgrade it to the latest version. This ensures compatibility with the ESXi host and addresses potential bugs.
  4. Check for Errors in Logs: Examine the VM’s logs, including the vmware.log file, for any error messages related to snapshot creation. These logs can provide insights into the root cause.

Resolution Steps:

  1. Update/Reinstall VMware Tools: Upgrade VMware Tools to the latest version. If issues persist, consider reinstalling VMware Tools to ensure a clean installation.
  2. Verify VM Configuration: Review and correct any misconfigurations in the VM settings, particularly those related to disk controllers and hardware versions.
  3. Increase Disk Space: If low disk space is the issue, expand the datastore or free up space by deleting unnecessary files.
  4. Restart VM: A simple restart of the VM might clear transient issues and allow for successful snapshot creation.


Encountering difficulties while taking quiesced snapshots in VMware VMs can be resolved through a systematic investigation of potential issues. By addressing VMware Tools compatibility, disk space concerns, and VM configuration issues, users can ensure smooth snapshot operations and maintain data consistency.