Filesystem quota
================

Index files
-----------

It's a good idea to keep index files in a partition where there are no
filesystem quota limits. The index files exist to speed up mailbox operations,
so Dovecot runs more slowly if it can't keep them updated. You can specify the
index file location by appending ':INDEX=/somewhere' to <mail_location>
[MailLocation.txt].

Since v1.0.rc27 Dovecot can handle "out of disk space" errors in index file
handling and transparently move to in-memory indexes. It'll use the in-memory
indexes until the mailbox is re-opened. Earlier versions will break more or
less badly.

mbox
----

It's a good idea to have 'mbox_lazy_writes=yes' (default), otherwise Dovecot
might give "Not enough disk space" errors when opening the mailbox, making it
impossible to expunge any mails.

If user has run out of quota and index files are also in memory (because
they're also over quota), it's possible that message flag changes are lost.
This should be pretty rare though because Dovecot keeps some extra space
allocated inside the mbox file for flag changes.

Example preferred configuration:

---%<-------------------------------------------------------------------------
mail_location = mbox:~/mail:INBOX=/var/mail/%u:INDEX=/var/no-quotas/index/%u
---%<-------------------------------------------------------------------------

Maildir
-------

Maildir needs to be able to add UIDs of new messages to 'dovecot-uidlist' file.
If it can't do this, it can give an error when opening the mailbox, making it
impossible to expunge any mails.

Currently the only way to avoid this is to use a separate partition for the
uidlist files where there are no filesystem quota limits. You can do this by
appending ':CONTROL=/somewhere' to <mail_location> [MailLocation.txt].

Example preferred configuration:

---%<-------------------------------------------------------------------------
mail_location =
maildir:~/Maildir:INDEX=/var/no-quotas/index/%u:CONTROL=/var/no-quotas/control/%u
---%<-------------------------------------------------------------------------

Note that if you change the location of the control files, Dovecot will look in
the new CONTROL directory ('/var/no-quotas/control/%u') for the subscriptions
file.

Quota reporting
---------------

Dovecot supports filesystem quota reporting using a quota plugin. New features
in Dovecot v1.1 include:

 * RPC quota (for NFS) support.
 * Inode quota is reported as message count quota for <Maildir>
   [MailboxFormat.Maildir.txt] and <Cydir> [MailboxFormat.Cydir.txt] formats.
 * Group quota is supported. It's used if user quota doesn't exist, or if quota
   parameters contains "group".

Parameters
----------

All of these require v1.1+:

 * user: Report only user quotas, don't fallback to showing group quotas.
 * group: Report only group quotas
 * inode_per_mail: Report inode quota as "number of message" quota.
 * noenforcing: Don't try to enforce quotas by calculating if saving would get
   user over quota. Only handle write failures.
 * mount=<path>: Report quota from given path. Default is to use the path for
   the mail root directory.

If you want to give multiple parameters, separate them with ':' (e.g.
"inode_per_mail:noenforcing").

Examples
--------

---%<-------------------------------------------------------------------------
protocol imap {
  mail_plugins = quota imap_quota
}

plugin {
  quota = fs:user
}
---%<-------------------------------------------------------------------------

If you want to see both user and group quotas as separate quota roots, you can
use this with v1.1:

---%<-------------------------------------------------------------------------
plugin {
  quota = fs:User quota:user
  quota2 = fs:Group quota:group
}
---%<-------------------------------------------------------------------------

If you have your mails in two filesystems, you can create two quota roots with
v1.1:

---%<-------------------------------------------------------------------------
plugin {
  # Assuming INBOX in /var/mail/ which is mounted to /
  quota = fs:INBOX:mount=/
  # Assuming other mailboxes are in /home mount
  quota2 = fs:Others:mount=/home
}
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2010-05-24 04:42)
