Dec
04

POSH: VSS Writer Check for Application Consistent Snapshots on Nutanix – #SQL #Exchange

Enabling of application consistent snapshot in Nutanix results in leveraging VMware tools. VMware tools acts as the requestor to talk to the guest virtual machine’s VSS writers. Application-consistent snapshots quiesce all IO, completes all open transaction and flushes caches so everything is consistent. The Volume Shadow Copy Service will freeze write IO while the native Nutanix snapshot takes place so all data and metadata is written in a consistent mater. Once the Nutanix snapshot takes place, the Volume Shadow Copy Service will the thaw the system and queued writes will occur.

To make sure the VSS writers are not having any problems, you can use the following script — VSS_Writer_Check_Nutanix —-.

The function that actually checks the virtual machine comes from Microsoft, <link>.

The Nutanix bits are listed below. The script finds all of the consistency groups that have VSS enabled. It assumes that all consistency groups are using the default machine name for the consistency group.


#Get a list of all Consistency Groups
$pdvss = Get-NTNXProtectionDomainConsistencyGroup

#array of all the appConsitentVMs
$appConsitentVM = @()

Foreach ($vssVM in $pdvss)
{

if ($vssVM.appConsistentSnapshots)

{ #Get a list of all the VM's that are using VSS
$appConsitentVM += $vssVM.consistencyGroupName

}

}

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