Splitting Metadata from Partitions
**********************************

Important:

  This only applies to Cyrus IMAP version 2.3 and later

The traditional layout for a Cyrus IMAP mailbox spool directory is to
include the mailbox message data and mailbox metadata in the same
directory tree. The mailbox message data and mailbox metadata differ
in size and frequency of updating, which in larger deployments may
justify using different storage layers for each.

The mailbox message data, which consists of many (small) message
files, is not updated as frequently and does not require as much
storage performance as the mailbox metadata, which consists of
databases that are updated frequently and have a high volume of
accesses and updates. The mailbox message data usually requires
significant storage volumes, while the mailbox metadata does not.

To transition from the traditional Cyrus IMAP mailbox spool directory
tree layout to a split setup, use the following procedure.

**Procedure 13.1. Transition from Traditional Mail Spool to Split Data
Mail Spool**

   Create a new partition in **/etc/imapd.conf**, aptly named
   **splitmeta** in the following example configuration snippet:

      metapartition_files: header index cache expunge squat
      metapartition-default: /var/spool/cyrus
      metapartition-splitmeta: /var/spool/splitmeta/metadata
      partition-default: /var/spool/cyrus
      partition-splitmeta: /var/spool/splitmeta/partition

   Create the directory tree being referred to in the new
   configuration:

      # su -s /bin/bash - cyrus -c '/usr/lib/cyrus-imapd/mkimap /etc/imapd.conf'

   Reload the Cyrus IMAP service. Please refer to Reloading Cyrus IMAP
   Services for more details on doing so.

   Rename all mailboxes, using the new partition as the location for
   the renamed mailbox. One example rename command is included below:

      cyradm> renamemailbox user/john.doe@example.org user/john.doe@example.org splitmeta
