[Dovecot] Haha wow, thats freakin cool... mdbox

[Stan Hoeppner]

Daniel Luttermann put forth on 7/18/2010 1:05 PM:
> Stan Hoeppner wrote on 18.07.2010:
> 
>> What happens when these indexes become corrupted, get accidentally deleted, or
>> have the permissions accidentally changed in a way that they become unreadable
>> by Dovecot?  Does Dovecot still report the messages as being in the correct
>> folder?
> 
> during my tests I've copied and deleted some mails, copied whole
> mdbox-files etc. and after some time the IMAP session was dropped by
> Dovecot. In the logfile I've found this:
> 
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Error: Corrupted transaction log file /home/vmail/dlutt.de/testuser/mdbox/mailboxes/Papierkorb/dbox-Mails/dovecot.index.log seq 2: file size shrank (sync_offset=14724)
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Error: Index /home/vmail/dlutt.de/testuser/mdbox/mailboxes/Papierkorb/dbox-Mails/dovecot.index: Lost log for seq=2 offset=14724
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Warning: fscking index file /home/vmail/dlutt.de/testuser/mdbox/mailboxes/Papierkorb/dbox-Mails/dovecot.index
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Warning: mdbox /home/vmail/dlutt.de/testuser/mdbox/storage: rebuilding indexes
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Error: /home/vmail/dlutt.de/testuser/mdbox/mailboxes/INBOX/dbox-Mails/dovecot.index reset, view is now inconsistent
> Jul 18 17:36:18 tux dovecot: imap(testuser at dlutt.de): Disconnected: IMAP session state is inconsistent, please relogin. bytes=119/850
> 
> After a relogin all mails were available and readable without manually
> fixing the index. Don't know if this always successful but it seems
> that Dovecot can rebuild the index without problems.

That's not the scenario I described.  You manipulated mail files which Dovecot
had already indexed, and Dovecot rebuilt the indexes when I saw the file
locations had changed.  The key here is that you manually, physically, moved
files around to different directories.  All Dovecot must do at that point is
look at where those files now reside, and rebuild the index according to their
current location.

What I was asking is what happens when you manually delete the index file out
from underneath Dovecot?  If files never got moved, but the index file says
they're in dir "X" when they physically reside in dir "Y", how does Dovecot
recover and correctly recreate the index?  At this point Dovecot has no
information about the files having been "moved" because the index file which
contains this "Y -- X" mapping information is now gone, deleted.

-- 
Stan