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The Veeam VMware: Datastore Unknown Files Analysis monitor triggers a lot of alerts

KB ID: 2974
Product: Veeam Management Pack for Microsoft System Center
Version: 8.0 Update 6
Published: 2019-07-04
Last Modified: 2020-08-28
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Challenge

The Veeam VMware: Datastore Unknown Files Analysis monitor triggers a lot of alerts.
The Veeam VMware: Datastore Unknown Files Analysis monitor and the Scan Datastore for Unknown Files task show different results. 
The UnknownFilesGB metric value displayed by the Veeam VMware: Datastore Unknown Files Analysis monitor is much higher than the value displayed by the Scan Datastore for Unknown Files task.

Cause

You may encounter the issue in the following cases:

•    You migrate a virtual machine to a new storage location. 
VMware vSphere keeps a copy of VM files both on the source and destination datastores till the end of the migration process. However, VM files that are located on the source datastore are no more connected to the migrated VM, and such VM files are reported as garbage files. 
This is why the UnknownFilesGB metric may show inaccurate value and the Veeam VMware: Datastore Unknown Files Analysis monitor may trigger alerts for the affected datastores.
Veeam does not recommend using the Veeam VMware: Datastore Unknown Files Analysis monitor for datastores involved in VM migration processes.

•    3rd-party solutions replicate, back up or copy VM files without registering these files on the vCenter Server side. 
The Veeam VMware: Datastore Unknown Files Analysis monitor identifies such files as files not managed by the vCenter Server.
In this case, both the UnknownFilesGB metric and the Scan Datastore for Unknown Files task will always show inaccurate values.

•    A shared datastore is connected to two different vCenter Servers. 
The Veeam VMware: Datastore Unknown Files Analysis monitor tracks VM files on one vCenter Server and identifies VM files that belong to another vCenter Server as unknown files. 

In this case, both the UnknownFilesGB metric and the Scan Datastore for Unknown Files task will always show inaccurate values.

Solution

In case the issue is caused by the VM migration process, you can do the following:

•    Increase the UnknownFilesGB parameter value specified for the Veeam VMware: Datastore Unknown Files Analysis monitor. For more information, see the Veeam MP for VMware Operations Guide, section Overriding Performance Analysis Monitors.

•    Increase the NumSamples parameter value specified for the Veeam VMware: Datastore Unknown Files Analysis monitor. For more information, see the Veeam MP for VMware Operations Guide, section Overriding Performance Analysis Monitors.

•    Decrease the DatastoreScanInterval parameter value specified for the Collector that gathers data on datatstores involved in the VM migration process. For more information, see the Veeam MP for VMware Operations Guide, section Collector Settings
By default, Collectors query vCenter Servers every 3 hours.

When the VM migration process is over, the Veeam VMware: Datastore Unknown Files Analysis monitor may still trigger alerts in the following cases:
•    The Collector has not run a new query yet, or another VM migration process has  already started by the time the Collector ran the new query.
•    vSphere API reports outdated datastore capacity, free space and VM size values. 
Collectors gather data via vSphere API and calculate the UnknownFilesGB metric value using the following formula: unknownFilesGB = [total datastore space usage] – [free space] – [space used by known VM datastore files], in GB. 

If none of the cases described in this article apply, you can run the Scan Datastore for Unknown Files task to get the list of unknown files detected on the affected datastore. For more information on the task, see the Veeam MP for VMware Operations Guide, section Scan Datastore for Unknown Files Task.
However, keep in mind that the Scan Datastore for Unknown Files task increases the load on the vCenter Server and may take a long time to complete. That is why Veeam recommends that you run this task only for those datastores reported by the Veeam VMware: Datastore Unknown Files Analysis monitor.

NOTE: As a workaround, you can disable the Veeam VMware: Datastore Unknown Files Analysis monitor for specific datastores. The Veeam VMware: Datastore Free Space Analysis monitor will continue running and reporting on free space left on these datastores.
 

More information

Should you have any questions, contact Veeam Support.
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