In general, most backup vendors (For backing Microsoft Applications) integrates with Microsoft VSS framework & 3rd party storage vendor to ensure Application consistent backup, and that is where 'VSS Hardware providers' come into picture. When you installed SnapCenter plug-in it has also installed it's version of 'Data ontap vss hardware provider', which the MS VSS framework will call out during the SnapCenter backup procedure and this 'VSS hardware provider' is always PRIORITIZED above the other/Microsoft software provider.
As I read, before installing the SnapCenter plug-in host for SQL host, it was VERITAS NetBackup. This suggests VERITAS NetBackup was deployed to backup SQL databases hosted on NetApp ? If yes, that means there must be 'SanpDrive' component installed on the host which NetBackup used via VSS framework to trigger and capture Hardware Level snapshot ? If so, then both cannot work together. Therefore, you must unregister the vss hardware provider installed with SnapDrive.
1) Using PowerShell/cmd prompt, determine whether the SnapDrive for Windows VSS Hardware Provider is registered:
vssadmin list providers
2) From the <SnapDrive directory>, unregister the VSS Hardware Provider (i.e SnapDrive for Windows): navssprv.exe -r service –u
3) Verify that the VSS Hardware Provider was removed: vssadmin list providers
Hopefully, there is only one registered vss hardware providers available.
In case there is none, you can follow this kb to manually register the SnapCenter vss hardware provider or simple uninstall and re-isntall plug-in.
https://kb.netapp.com/Advice_and_Troubleshooting/Data_Protection_and_Security/SnapCenter/How_to_manually_register_the_Data_ONTAP_VSS_Hardware_Provider
