Just want to discuss the impact on the implications when one HDS server goes down (out of 2) is taken down for maintenance. From what I understand there should be no impact. How long does it take to replicate the data back, if one HDS server is down for 12 hrs or so ?
As the HDS does not perform any routing, there is definitely no customer-facing impact to taking it down for maintenance. Replication speed will depend on a number of factors - server size, call volume, network connectivity between sides, etc.
I would expect that the replication would take far less than the 12 hours the server was down for, likely somewhere between 30 minutes and 4 hours. Just a guess though, as there are so many factors that would go into it.