I am going to deploy Zimbra for around 400000 users.
And will migrate the mailbox from existing mailserver.
The reason is Zimbra has already stable and has millions of mailbox deployed.
Also proven in a large scale deployment by Comcast, around 12 Millions users if I'm not mistaken.

If I give each user 1G quota then I will need maximum 400TB storage.
I'm going to use NetApp for SAN storage.

If I separate the user mailboxes into 2 Zimbra Mailbox Server (200000 users each), then each server should have 200TB partition comes from NetApp storage.

My question is, what is the most common method to mount a 200TB on a server?
Any maximum size for mailbox partition? Should I mount the disk using NFS?
Does Zimbra still perform well?
Or any other explanation on how to deploy Zimbra better than what I am planning to do?

Thank you