Skip to main content
NetApp Knowledge Base

SCV - What "Quiescing Applications" and "Unquiescing Applications" do and how it relates to data I/O

  1. Last updated
    May 26, 2025
  2. Save as PDF
Views:
231
Visibility:
Public
Votes:
0
Category:
snapcenter
Specialty:
snapx
Last Updated:
5/26/2025, 12:32:59 PM

Applies to

  • SnapCenter Plug-in for VMware [SCV]

Answer

SCV leverages VMware Tools to quiesce the file system in the virtual machine. For Each VM inside the SCV Resource Group, a temporary VMware snapshot is taken with the check box "Quiesce guest file system(requires VM tools)";  VM guest memory is not included in VM consistency Snapshots:

VMware_Quiesced_snapshot.png

Per VMware documentation:

  • When you quiesce a virtual machine, VMware Tools quiesces the file system of the virtual machine. 
  • A quiesce operation ensures that a snapshot disk represents a consistent state of the guest file systems. 
  • Quiesced snapshots are appropriate for automated or periodic backups.-Quiescing a file system is a process of bringing the on-disk data of a physical or virtual computer into a state suitable for backups. This process might include such operations as flushing dirty buffers from the operating system's in-memory cache to disk, or other higher-level application-specific tasks.
  • SnapCenter requests VMware to start the quiesce process stopping I/O operations for a very small amount of time in order to take an application consistent backup, once the Snapshot is taken, it will then request to start the unquiesce process and restart normal operations.

From the SCV job logs we can see the whole process and it only takes a few seconds to complete (Quiesce --> Request Snapshot creation --> Create Snapshot -->Unquiesce):

SCV wfe logs: 

2024-04-22 22:30:34.485 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Creating task for job 6079 with name Quiescing Applications
2024-04-22 22:30:34.485 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.u.RestClientUtil                 : Connecting to server url:  http://localhost:8155/api/v1/jobs/6079/tasks
2024-04-22 22:30:34.493 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Completed creating job on SnapCenter Server.
2024-04-22 22:30:34.493  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Quiescing Applications,  Starting
2024-04-22 22:30:34.493 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.u.LogHelper                        : Starting Quiesce activity
2024-04-22 22:30:34.493 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCVBackupServiceImpl             : Quiesce on SCV
2024-04-22 22:30:34.493 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.u.RestClientUtil                 : Connecting to scv url:  https://localhost:8144/scbr/smcoreplugin/quiesce
2024-04-22 22:30:34.581 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCVBackupServiceImpl             : Completed quiesce on SCV.
2024-04-22 22:30:34.581 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.u.LogHelper                        : Quiesce activity was successful
2024-04-22 22:30:34.581  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Quiescing Applications, Completed
.
.
.
024-04-22 22:30:34.701  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Creating Snapshot copy,  Checking CanExecute
2024-04-22 22:30:34.701 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Creating job on SnapCenter Server.
2024-04-22 22:30:34.701 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Creating task for job 6079 with name Creating Snapshot copy
2024-04-22 22:30:34.701 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.u.RestClientUtil                 : Connecting to server url:  http://localhost:8155/api/v1/jobs/6079/tasks
2024-04-22 22:30:34.709 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Completed creating job on SnapCenter Server.
2024-04-22 22:30:34.709  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Creating Snapshot copy,  Starting
2024-04-22 22:30:34.709 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.a.SnapshotActivity                 : Starting snapshot activity
2024-04-22 22:30:34.709 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSStorageServiceImpl            : Calling create snapshot on SnapCenter server.
.
.
.
2024-04-22 22:30:37.067 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSStorageServiceImpl            : Completed creating snapshot on SnapCenter Server.
2024-04-22 22:30:37.067 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.a.SnapshotActivity                 : Schedule type is DAILY
2024-04-22 22:30:37.067 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.a.SnapshotActivity                 : Backup name is: NWT_Group_04-22-2024_22.30.00.0657
2024-04-22 22:30:37.067  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Creating Snapshot copy, Completed
.
.
.
024-04-22 22:30:37.081  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Unquiescing Applications,  Checking CanExecute
2024-04-22 22:30:37.081 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Creating job on SnapCenter Server.
2024-04-22 22:30:37.081 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Creating task for job 6079 with name Unquiescing Applications
2024-04-22 22:30:37.081 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.u.RestClientUtil                 : Connecting to server url:  http://localhost:8155/api/v1/jobs/6079/tasks
2024-04-22 22:30:37.089 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCSJobServiceImpl                : Completed creating job on SnapCenter Server.
2024-04-22 22:30:37.089  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Unquiescing Applications,  Starting
2024-04-22 22:30:37.089 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.u.LogHelper                        : Starting Unquiesce activity
2024-04-22 22:30:37.089 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCVBackupServiceImpl             : Unquiesce on SCV
2024-04-22 22:30:37.089 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.u.RestClientUtil                 : Connecting to scv url:  https://localhost:8144/scbr/smcoreplugin/unquiesce
2024-04-22 22:30:37.139 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.r.SCVBackupServiceImpl             : Completed unquiesce on SCV.
2024-04-22 22:30:37.139 DEBUG NETAPPSCP1 --- [      Thread-85] c.n.w.u.LogHelper                        : Unquiesce activity was successful
2024-04-22 22:30:37.139  INFO NETAPPSCP1 --- [      Thread-85] c.n.w.m.WorkflowExecutor                 : Activity - Unquiescing Applications, Completed

Additional Information

If you manually want to check whether creation of a VMware consistent snapshot works from vSphere, without using SCV, you need to right click the VM, choose 'Snapshots', then 'Take Snapshot', then choose the check box "Quiesce guest file system(requires VM tools)";  

VMware_Quiesced_snapshot.png

 

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.