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:
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 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.  | 
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 NOTE: On Linux®-based virtual machines, the plug-in always generates crash-consistent snapshots. You can install the VMware SYNC driver on Linux-based systems to freeze and thaw filesystem I/O and obtain a consistent snapshot that reduces the risk of data loss and data corruption after restore. However, creating quiesced snapshots using SYNC driver requires waiting for I/O to drain in the Guest OS. This activity can affect time-sensitive applications.  | 
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 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.  | 
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 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 need to be perform for VSS-enabled applications, like SQL Server®, Exchange, and SharePoint®, after restoring an image-level backup.  | 
Quiescing is only supported on Windows®-based virtual machines. You can set the backup preferences to enable quiescing for all or specific virtual machines.
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 To enable quiescing for all virtual machines managed by an ESXi or vCenter Server, select the server, and in the Actions list, click Set Backup Preferences.  | 
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 To disable quiescing for all virtual machines managed by an ESXi or vCenter Server, select the server, and in the Actions list, click Set Backup Preferences.  | 
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