Hi
Jmo91,
Here is how it worked for me:
In my previous example I had 2 Servers X 2 Sites X 2 No. of DAGs =
8 servers.
Site Resilience User Distribution Model: Active/Active (Single DAG)
Now to change is same configuration to Active/Active (Multiple DAGs) model
We will notice that the Exchange Environment Configuration Section in the INPUT sheet
No. of Database Availability Groups has changed to something else:
Database Availability Group Multiplier:
Enter the number of database availability groups you will deploy in your environment.
If you are deploying an Active/Active (Multiple DAGs) site resilient architecture then by default you have a minimum of 2 DAGs being deployed.
If your design requires additional DAGs utilize this field by entering in the multiple you require.
For example if you are planning to have 2 DAGs active in Datacenter 1 and 2 DAGs active in Datacenter 2 (with passives in the opposing datacenter), you would enter 2 in this field.
Basically to match our previous example we have to make changes:
2 Servers X 2 Sites X 1 DAG Multiplier =
8 servers.
NOTE:- As the Multi model automatically multiples it by 2 to match the configuration.
Exchange Environment Configuration
|
Value
|
Global Catalog Server Architecture
|
64-bit
|
Server Multi-Role Configuration (MBX+CAS)
|
Yes
|
Server Role Virtualization
|
No
|
High Availability Deployment
|
Yes
|
Number of Mailbox Servers Hosting Active Mailboxes / DAG (Primary Datacenter)
|
2
|
Database Availability Group Multiplier
|
1
|
Site Resilience Configuration
|
Value
|
Site Resilient Deployment
|
Yes
|
Site Resilience User Distribution Model
|
Active/Active (Multiple DAGs)
|
Site Resilience Recovery Point Objective (Hours)
|
24
|
Activation Block Secondary Datacenter Mailbox Servers
|
No
|
Dedicated Disaster Recovery Mailbox Servers in Secondary Datacenter
|
No
|
Mailbox Database Copy Configuration
|
Value
|
Total Number of HA Database Copy Instances (Includes Active Copy) within DAG
|
3
|
Total Number of Lagged Database Copy Instances within DAG
|
1
|
Number of HA Database Copy Instances Deployed in Secondary Datacenter
|
1
|
Number of Lagged Database Copy Instances in Secondary Datacenter
|
1
|
Even when we tried best to keep the configuration match the Active/Active (Single DAG) model, the Volume design changes from 4DB/Vol to 2DBs/Vol. Irrespective of the fact that we actually have the exact same hardware, server and user count.
Volume Requirements (Sheet)
Volume Design
|
|
Volume Design Architecture
|
Multiple DBs / Volume
|
|
|
|
|
Volume Configuration
|
Suggested Number of Databases / Volume
|
2
|
Number of Databases / Volume
|
2
|
Recommended Number of Database+Log Volumes / Server
|
6
|
Recommended Number of Transaction Log Volumes / Server
|
0
|
Number of Spare Volumes / Server (used by AutoReseed)
|
2
|
Number of Restore Volumes / Server
|
1
|
Total Recommended Exchange Volumes / Server
|
9
|
There is a catch which I found while backtracking the formulas and comments for this value. Multiple DAG user distribution model is nothing but, Active/Passive Model but with multiple Active sites using multiple DAGs.
As per individual DAG perspective this is no different than an Active/Passive model. This can be observed in Distribution Sheet which represents a single DAG view and failover scenario.
Once we have established that its a A/P model, looking at the comments for the below field, we can see that #DB/Volume = #DB copies/site
INPUT (Sheet)-Storage Options- Number of Databases / Volume Matches Total Database Copy Count
By default, the number of copies that will be deployed on a volume will match the total number of copies available per database (per site in A/P scenarios).
For example, if you design an A/A solution that has two copies in the primary datacenter and two copies in the secondary, then when deploying multiple databases per volume, you will have four copies per volume.
If you want to deploy less copies per volume, select No. In this scenario, the calculator will use half the total number of copies/disk.
Storage Options
|
Value
|
Consider Storage Designs Utilizing JBOD (if applicable)
|
Yes
|
Consider Multiple Databases / Volume Deployment
|
Yes
|
Number of Databases / Volume Matches Total Database Copy Count
|
Yes
|
Automatically Calculate Number of Exchange Database Volumes Required
|
Yes
|
This explains why we have the 2DB/Volume. Lets look at the configuration once more:
2 Servers X 2 Sites X 1 DAG Multiplier =
8 servers.
Per site: 2 Servers X 1 Sites X 2 = 4 servers
(NOTE this is for 2DAGs)
Per site per DAG: 2 servers
Hence for individual DBs; we have only 2 servers = only 2 database copies available per site per DAG. This resulted in 2DB/Volume.
Lets fix this:
I have increased the no. of server per site to 4 and other options are highlighted.
4 Servers X 2 Sites X 1 DAG Multiplier =
16 servers. (8 servers per DAG)
Exchange Environment Configuration
|
Value
|
Global Catalog Server Architecture
|
64-bit
|
Server Multi-Role Configuration (MBX+CAS)
|
Yes
|
Server Role Virtualization
|
No
|
High Availability Deployment
|
Yes
|
Number of Mailbox Servers Hosting Active Mailboxes / DAG (Primary Datacenter)
|
4
|
Database Availability Group Multiplier
|
1
|
|
Mailbox Database Copy Configuration
|
Value
|
Total Number of HA Database Copy Instances (Includes Active Copy) within DAG
|
7
|
Total Number of Lagged Database Copy Instances within DAG
|
1
|
Number of HA Database Copy Instances Deployed in Secondary Datacenter
|
3
|
Number of Lagged Database Copy Instances in Secondary Datacenter
|
1
|
Volume Design
|
|
Volume Design Architecture
|
Multiple DBs / Volume
|
|
|
|
|
Volume Configuration
|
Suggested Number of Databases / Volume
|
4
|
Number of Databases / Volume
|
4
|
Recommended Number of Database+Log Volumes / Server
|
6
|
Recommended Number of Transaction Log Volumes / Server
|
0
|
Number of Spare Volumes / Server (used by AutoReseed)
|
2
|
Number of Restore Volumes / Server
|
1
|
Total Recommended Exchange Volumes / Server
|
9
|
As you can see that the Number of Databases / Volume now shows as 4 DBs.
Few insights from the formulas in Role Requirements sheets C81,C82 cell:
Calculated Maximum Databases per Volume
|
8
|
Recommended Databases per Volume
|
4
|
Things considered for individual DAGs
Single DAG model: MIN ((Max Disk size/max. DB size calculated) , (No. DB copies in Primary site + No. DB copies in 2<sup>nd</sup> Site))
Active Passive or Multi DAGs model: MAX(No. DB copies in Primary site ,
No. DB copies in 2<sup>nd</sup> Site)
Conclusion:
Changes to high availability and site resilience over previous versions \ Multiple databases per volume
The key is that the number of copies of each database that you have should be equal to the number of database copies per disk. However its not mentioned in TechNet that this is limited to per site or