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NetVault Backup Plug-in for VMware 12.3 - User Guide

Introducing NetVault Backup Plug-in for VMware Installing the plug-in Configuring the plug-in Defining a backup strategy Using the image-level backup method Using the file-level backup method Restoring image-level backups Restoring file-level backups Troubleshooting

Enabling or disabling quiescing of virtual machines

This section includes the following topics:

About quiescing virtual machines

A virtual machine can be quiesced to create consistent snapshots for backups. Quiescing is performed using the VMware VSS component, which is provided with VMware Tools. The VMware VSS component is automatically installed when you install VMware Tools on the virtual machines.

Quiescing is only supported on Windows-based virtual machines. You can enable or disable quiescing of virtual machines.

Depending on the quiescing method used, the plug-in generates the following types of snapshots:

Crash-consistent snapshots: Crash-consistent snapshots capture the volume state as it would be after a power outage. Such snapshots are not guaranteed to be free of incomplete I/O operations or data corruption. During a restore, there can be some data loss or corruption that can cause application failure.
File-system-consistent snapshots: For file-system-consistent snapshots, all file system I/O is temporarily frozen and dirty memory data is flushed to the disk before the snapshot is taken.
VSS-based application-consistent snapshots: For application-consistent snapshots, all application data in memory is written to the disk. Application-consistent snapshots reduce the amount of application-crash recovery that you must perform for VSS-enabled applications, such as SQL Server, Exchange, and SharePoint, after restoring an image-level backup.

Enabling quiescing of virtual machines

Quiescing is only supported on Windows-based virtual machines. You can set the backup preferences to enable quiescing for all or specific virtual machines.

1
Start the Backup Job Wizard, and click Create New next to the Selections list.
4
In the Backup Preferences dialog box, select the Quiesce VM for snapshot option.

Disabling quiescing of virtual machines

On virtual machines with high processor or IO load, the quiesce operation may timeout and cause the backup job to fail. In such cases, you can disable quiescing for all or specific virtual machines. When you disable quiescing, the plug-in uses crash-consistent snapshots to perform backups.

1
Start the Backup Job Wizard, and click Create New next to the Selections list.
4
In the Backup Preferences dialog box, clear the Quiesce VM for snapshot option.
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