Summary
Customer install cluster-aware clients on both nodes, import virtual name.
Creating backup then he can see only normal disks like C:\, D:\ but not quorum disk Q:\
Error
Could not see Quorum disk under backup specification
Cause
1. Open Failover clustering powershell – check the document below:
https://techcommunity.microsoft.com/t5/failover-clustering/powershell-for-failover-clustering-in-windows-server-2008-r2/ba-p/371297
2. And try to the get the resources – Check the provided document for reference.
Get-ClusterGroup -name "clustergroup name" | Get-ClusterResource
We found out the Quorum disk belongs to another group/resources with normal disks, hence could not see on backup specification
Fix
Move quorum disks to the same resource group with other disks