Questions in Lync 2013 HADR

Question

Hi Team,
One of the customer raised the query:
In our scenario, we want Active/Active High availability between different geolocations with RPO=0 and RTO near zero (seconds).
Questions:
1. Isn’t this possible with pool pairing and database availability AlwaysOn synchronous commit?
2. What is the bandwidth needed between both sites?
3. Do you think to achieve Active/Active high availability (RPO=0, RTO=+/-0) for Lync between 2 datacenters we should go with the following scenario:
--> Storage: virtualization (stretched LUNs)
-->Compute: Hyper-v Clustering (failover cluster)
-->DNS: Global Datacenter Server Load Balancer
4. What is the RTO and RPO in your proposed solution?
Please advise. Many Thanks.

Answer 1

1) No.  Pool paring doesn't automatically failover, therefore it does not meet the requirements.  Also, HA within a pool isn't supported across geographic locations, so I don't believe this requirement can be met within the supported model. 
It's possible if you have a solid enough pipe between the locations with very low latency that you could go unsupported with the old Metropolitan Site Resiliency model:
https://technet.microsoft.com/en-us/library/gg670905(v=ocs.14).aspx but not supported in 2013.
2) This can't be answered easily, it depends on what they're doing and using. How many users, how much archived data... the SQL mirroring will be quite a bit, as well as the shared presence data on front ends.  Will they use video between sites?  
Too many questions to get any kind of reliable answer.
3) If RTO/RPO is this critical, then I'm assuming it's voice.  If it's not, then a short outage should be more tolerable.  If it is voice, do not leave the supported model... just don't.  You don't want to be in that
situation when systems are down and it's your phone.  No live migrations, just what's supported via TechNet and virtualization whitepapers.
4) My proposed solution would be HA pools in both datacenters, built big enough it's unlikely to go down.   If the site does go down, pool failover can happen in a reasonable amount of time, perhaps 15 minutes if you're well prepared,
but phones could potentially stay online during this time. 
-Anthony
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This forum post is based upon my personal experience and does not necessarily reflect the opinion or view of Microsoft, its employees, or other MVPs.