Skype for Business HA, and DR

https://docs.microsoft.com/en-us/skypeforbusiness/plan-your-deployment/high-availability-and-disaster-recovery/high-availability

http://www.itprotoday.com/industry-perspectives/skype-business-2015-confirmation-pool-failover-and-failback

Summary of pool failover and failback for Skype for Business

some steps:

Get-CsRegistrarConfiguration -Identity ‘service:register:pool1’

Get-CsRegistrarConfiguration -Identity ‘service:register:pool1’

Get-CsBackupServiceStatus -PoolFqdn pool1

CMS Failover
Invoke-CsManagementServerFailover -WhatIf
Invoke-CsManagementServerFailover
Invoke-CsManagementServerFailover -WhatIf

POOL Failover
Get-CsRegistrarConfiguration -Identity ‘service:Registrar:pool1’
Invoke-CsPoolFailOver -PoolFqdn pool1
Get-CsRegistrarConfiguration -Identity ‘service:Registrar:pool1’
Get-csmanagementstorereplicationstatus | ft

CMS Failback
Invoke-CsManagementServerFailover -WhatIf
Invoke-CsManagementServerFailover
Invoke-CsManagementServerFailover -WhatIf

POOL Failback
Invoke-CsPoolFailBack -PoolFqdn pool1
Get-CsRegistrarConfiguration -Identity ‘service:Registrar:pool1’
Get-csmanagementstorereplicationstatus | ft