Hi all,

We have two sites and we set up one DAG which extends two sites.

each database has one active copy and one passive copy.

we do not have a lagged copy.

Is it recommended to have a lagged copy always?  any reason?

Thank you.

Good Evening,

That is based on the needs of your organization.

If a past point-in-time copy of mailbox data is a requirement for your organization, Exchange provides the ability to create a lagged copy in a DAG environment. This can be useful in the rare event that there's a logical corruption that replicates across the databases in the DAG, resulting in a need to return to a previous point in time. It may also be useful if an administrator accidentally deletes mailboxes or user data. Recovery from a lagged copy can be faster than restoring from a backup because lagged copies don't require a time-consuming copy process from the backup server to the Exchange server. This can significantly lower total cost of ownership by reducing end-user downtime

http://technet.microsoft.com/en-us/library/dd876874(v=exchg.150).aspx