I've filled out this form and I'm a little confused about some of the values it spit out. I entered 2 mailbox servers hosting active mailboxes, 1 DAG (active/passive), 3 instances of HA database copy, one ha database copy deployed in secondary datacenter, and 0 lagged copies. On the Role Requirements tab, it shoes 6, 18, and 18 for the number of database copies. What gives? I'm also not sure how it calculates required disk capacity. Today, I've got about 700GB of e-mail, including the transaction logs. Even with the loss of single instance storage, and calculating 50% database growth immediately, that's only about 1TB. If I want 3 copies of each database (including the active copy), that should be 3TB of required disk. However, the role caclulator says I need the following: Disk Space Requirements / Database / Server / DAG / Environment Database Space Required 1699 GB 10196 GB 30587 GB 30587 GB Log Space Required 72 GB 434 GB 1301 GB 1301 GB Database LUN Space Required/ 2077 GB 12461 GB 37384 GB 37384 GB Log LUN Space Required 80 GB 482 GB 1445 GB 1445 GB Restore LUN Space Required -- 1968 GB 5905 GB 5905 GB That's a lot more than 3TB so again, what gives? Thanks.

I assume that the number of the mailboxes is 1000 (As it can give me 6/18/18 on the number of database copies J) As I know, the database size is determined on the following things (Reference) · Backup/restore service level agreements (SLAs) · High availability architecture · Storage architecture And, I think you have already seen the description in the article below, right? “Database Space Required is the amount of space required to support each database and its corresponding copies. This value is derived from the mailbox size on disk, the data overhead factor, whether a dedicated restore LUN is available …” -------Refer to <“Disk Space Requirements” section in Exchange 2010 Mailbox Server Role Requirements Calculator> James Luo TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Any further update on this thread?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Not sure if it's the issue here, but I've noticed that if you don't put a maximum mailbox quota size in the calculator, it suggests an incredible amount of storage. So try putting a mailbox quota in to the calculator even if you don't really enforce one.