It's worthwhile noting that the 'FullReset' option for this cmdlet performs the same type of reset as 'QuorumLossRecovery' but in addition, rebuilds the local Skype for Business Server 2015 databases. This cmdlet reloads user data from the backup store for any routing groups currently in quorum loss but any data not yet written to the database could be lost when doing this.

To recover from quorum loss, the administrator needs to run the Reset-CsPoolRegistrarState -ResetType QuorumLossRecovery cmdlet to tell Windows Fabric to rebuild the replicas on the remaining FE servers, assuming there are enough to maintain pool quorum. If two of the replicas were to go down at the same time, the user will be placed into 'Limited Functionality' mode while all three replicas down means the user will be disconnected and the client will forever be in a 'Reconnecting.' state. The user will only experience a brief disconnect before full services are restored. If the Primary replica goes down, then one of the Secondary replicas will be promoted to become the Primary. Since all user requests are serviced by the Primary replica, if one of the secondary replicas were to go down, there will be no impact to the user at all.

Lets start by reviewing the user experience when quorum loss occurs.

What is skype for business 2015