File & Directory Locations
**************************

Cyrus IMAP maintains several directories for configuration, state and
data storage.  The locations of these directories and, in many cases,
of individual files, may be controlled by settings in imapd.conf(5).

* Archive Partitions

* Configuration file locations

* State Directories

* Per-user State Directories

* Directory Hashing

* Spool Directories

* Metadata Partitions

* Search Tiers


Partitions
==========

Partitioning is a means to divide storage resources into separate
pools and may be defined for the following types of data:

   * Mail Spool Partitions

   * Mailbox Metadata Partitions

   * Cyrus Backups

   * Archive Partitions

Please consult the documents linked above for more information on
these.

You may also find more examples and possible scenarios in the document
on Mailbox Distribution.

In general, Cyrus allows one to maintain several separate partitions
for each of these data types, and to establish rules governing
distribution of data within each pool.


Working With Partitions
=======================

All partition operations are controlled via settings in imapd.conf(5),
and thus require server restarts to effect. There are no
administrative commands to manipulate partitions.

Here are the settings for each class of partition:


Mail Spool Partitions
---------------------

While Cyrus itself has no default values for these settings, most
distributions use "default" and "/var/spool/cyrus" or
"/var/spool/cyrus":

   "defaultpartition:" <none>

      The partition name used by default for new mailboxes.  If not
      specified, the partition with the most free space will be used
      for new mailboxes.

      Note that the partition specified by this option must also be
      specified as *partition-name*, where you substitute ‘name’ for
      the alphanumeric string you set *defaultpartition* to.

   "partition-name:" <none>

      The pathname of the partition *name*.  At least one partition
      pathname MUST be specified.  If the **defaultpartition** option
      is used, then its pathname MUST be specified.  For example, if
      the value of the **defaultpartion** option is **default**, then
      the **partition-default** field is required.


Metadata Partitions
-------------------

Metadata is information used to process the mailbox data, rather than
the contents of the messages withing the mailbox.  Examples include
headers, caches, indexes, etc.

   "metapartition-name:" <none>

      The pathname of the metadata partition *name*, corresponding to
      spool partition **partition-name**.  For any mailbox residing in
      a directory on **partition-name**, the metadata files listed in
      *metapartition_files* will be stored in a corresponding
      directory on **metapartition-name**.   Note that not every
      **partition-name** option is required to have a corresponding
      **metapartition-name** option, so that you can selectively
      choose which spool partitions will have separate metadata
      partitions.

   "metapartition_files:" <empty string>

      Space-separated list of metadata files to be stored on a
      *metapartition* rather than in the mailbox directory on a spool
      partition. Allowed values: *header*, *index*, *cache*,
      *expunge*, *squat*, *annotations*, *lock*, *dav*, *archivecache*


Backup Partitions
-----------------

Cyrus Backups are a replication-based backup service for Cyrus IMAP
servers.

   "backuppartition-name:" <none>

      The pathname of the backup partition *name*.  At least one
      backup partition pathname MUST be specified if backups are in
      use.  Note that there is no relationship between spool
      partitions and backup partitions.


Archive Partitions
------------------

Cyrus Archiving will migrate mailbox data from the normal mail spool
partitions to separate archive partitions, based upon criteria such as
age and size.  Typical use cases would be to keep so-called “hot”
data, such as recent messages, on fast drives, such as SSDs, and
migrate “cold” data, such as older or large messages, to slower but
cheaper media.

   "archivepartition-name:" <none>

      The pathname of the archive partition *name*, corresponding to
      spool partition **partition-name**.  For any mailbox residing in
      a directory on **partition-name**, the archived messages will be
      stored in a corresponding directory on **archivepartition-
      name**. Note that not every **partition-name** option is
      strictly required to have a corresponding **archivepartition-
      name** option, but that without one there’s no benefit to
      enabling archiving.

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