Each server that is a member of the DAG needs the SME config wizard run on it and the DB's and TX's logs moved to separate LUN's. The Snapinfo folders are normally with the TX logs, if not on a separate LUN/Drive.
Once the Config wizard has been run on all nodes and completes with no errors, run the backup wizard and connect to the active server in the cluster. When you run through the backup wizard, it will prompt you and ask if you wish to create the backup job on all nodes of the DAG. Click yes . (This part is nearer the end).
You can use the wizard to create a SME job that exists on all the DAG servers. The scheduled job will run from the windows server that holds the windows cluster resource, but is not necesarily the active Exchange Mailbox server.
The SME job is cluster aware, so all even though the jobs technically start on the other servers, because the switch "-clusteraware" is used in the job syntax, the jobs dont run, except on the primary cluster resource owner. therefore if the primary cluster resource is moved to another server, the SME job would then run on there