Anyone got the info on how to configure failover for Zimbra Server?

Say I has 2 servers, server A and B, each has their own storage.

Server A is the active server and B is the backup.

Data should sync real time from Server A and B.

In the event of hardware failure in Server A, server B will be able to detect that and take over the network information of Server A automatically, the process should be transparent to the end users.

Anyone can help me on this?

Thanks in advance!