[Dovecot] Best way to change index location on mdbox

[Timo Sirainen]

On Fri, 2012-05-18 at 23:44 +0200, Patrick Westenberg wrote:
> right now my index directory is part of the users home directory:
> mail_home = /var/mail/%d/%n
> mail_location = mdbox:~/mdbox
> 
> I want the indexes to be stored in a different location:
> mail_home = /var/mail/%d/%n
> mail_location = mdbox:~/mdbox:INDEX=/var/indexes/%d/%n
> 
> If I just switch this setting and reload the configuration, no e-mails 
> are shown to the user.

You must not lose indexes with mdbox or you'll lose message flags and
mails may also end up going to wrong mailboxes.

> After restoring the whole maildir I deleted all dovecot.index.*-files 
> from that user and starting dovecot with the new index directory
> setting, I got the following error after connecting.
> I expected the index files to be regenerated but I got an error:
> 
> May 18 23:11:12 imap(test at example.com): Panic: file mail-storage.c: line 
> 787 (mailbox_check_mismatching_separators): assertion fail
> ed: (strncmp(vname, ns->prefix, ns->prefix_len-1) == 0)

This is a little bit strange bug that is also happening to another guy.
I haven't been able to reproduce it.

> How can I change the index directory without losing mails?

The easiest and the most reliable solution would be to just move the
index files to their new location while Dovecot is stopped.