We're upgrading from Exchange 2010 to 2016 and I already have the design on my head, which will be similar to what we have on 2010, but I'm unsure regarding how many servers will we need to accommodate our mailboxes and run smoothly.
I've tried to use the Exchange Server Role Requirements Calculator v9.1, but I'm not sure why it keeps giving me so many servers that it can't be right!
The idea is to have enough servers to run smoothly even in the case of 1 of them failing (DAG)
If someone could give me some thoughts on the below, that would be much appreciated.
Six databases, with around 200GB each
Total number of users is 1800, around 300 mailboxes per database
Average size of each mailbox is around 400mb (limit is 3GB) (they're small because we have a third-party archiving solution stubbing messages)
Growth: I don't expect us to grow a lot in mailbox numbers, let's say 25% in the next 2 years. In terms of mailbox size, I would say each mailbox could grow up to 50% in the next 2 years, so, each database would go up to 300GB or 350GB.
Outlook - 80% users will work in Online Mode and 20% in Offline Mode.
Daily email flow - Average of 5000 outbound and 12000 inbound emails. In terms of size, they're mostly small emails with a few kb.
Servers will be virtual machines in VMware.
Hosts servers have CPU Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz (logical processors 32) and no RAM restrictions (can go up to 92GB).
One Active/Passive DAG with 2 servers in production (active) and 3 servers on a failover site (passive).
The 2 servers in PROD will have 1 copy of all databases and on a day-to-day operations will run 3 active and 3 copies with preference 2, so they get activated if the other server crashes (basically, load will be balanced between 2 servers).
On the failover site we'll have 2 servers with 1 copy of all databases and preference 3 and 4 and activation blocked, so they only get activated manually (in case the prod site dies). The third server on the failover site will have lagged database copies and will only be used in case database corruption happens on the other servers and we cannot recover them.
So, my 3 main questions are:
1. Will 2 servers in production be enough to run these 6 databases smoothly (3 databases in each server)?
2. Will 1 server be enough to run all 6 databases smoothly (in case the other one crashes)?
3. Do you recommend a different design/solution?
Please let me know if you need more info. I can always draw the design and attach it, to help visualising this scenario.
Thank you in advance.