This chapter describes how to migrate from a Messaging Server 8.0.1 or prior "classic" message store to Messaging Server 8.0.2 and Cassandra message store. It assumes that you have chosen a target deployment, and have developed an architectural design and deployment plan.
The high-level steps to migrate to Cassandra Message store include:
Upgrading current front-end Message Transfer Agent (MTA) hosts, Messaging Multiplexor (MMP) hosts, and Webmail Server (mshttpd) hosts to at least Messaging Server 8.0.1.
You must upgrade these hosts to at least Messaging Server 8.0.1 to support store affinity groups.
The Cassandra message store changes the semantics of the mailHost attribute in LDAP. Instead of referring to a physical host, in Messaging Server 8.0.2 "mail host" refers to a store affinity group. You configure the store affinity group with the proxy:maihost.storehostlist msconfig option. You must configure store affinity groups on front-end MTAs for robust Cassandra message store delivery. Store affinity groups enable the MTA to route to an alternate LMTP server in the list if the first one listed is unavailable. Affinity groups are used to distribute ENS delivery events so that IMAP IDLE works without the need to broadcast all delivery events to all IMAP servers.
If not already using LMTP, enabling LMTP server on the classic message store host. When you enable LMTP server, you must restart the dispatcher on each classic store.
For more information, see "Installing Message Access Tier Hosts".
If not already using LMTP for delivery, switch front-end MTAs to use LMTP for delivery. When you switch front-end MTAs to use LMTP, you must run the imsimta restart smtp command on those MTAs whose delivery options you changed.
For more information, see "Installing MTA Tier Hosts".
Installing and configuring the Cassandra message store.
For more information, see "Cassandra Message Store Pre-Installation Tasks" and "Installing and Configuring the Messaging Server Software".
Using the rehostuser command to migrate users from classic store to Cassandra store.
For more information, see the rehostuser topic in Messaging Server System Administrator's Guide.
For example, the following rehostuser command migrates user joe to affinity group ngstore using message access server ma1.
rehostuser -u joe -d ngstore -R ma1
The -d target for the rehostuser command becomes the user's mailHost attribute. For the end users to have access to their email after migration, that target must either match one of the host names in the storehostlist option for that affinity group, or must match the name of the affinity group. Use of the -R option is only required if the -d target is not a resolvable host name.
Note:
The storehostlist option for an affinity group must be set to the same value on all front-end MTA, MMP, and mshttpd hosts, and all message access-tier hosts. Use fully qualified domain names when referring to hosts, both with the rehostuser command and in the storehostlist option.