[Dovecot] Mbox corruption - Inbox beginning with 'FFrom' or 'FrFrom'

[Erik Kratzenberg]

On 04/29/10 13:52, Timo Sirainen wrote:
> On Wed, 2010-04-28 at 10:46 -0400, Erik Kratzenberg wrote:
>>>>      -Dovecot.log : Mar 29 11:00:06 Error: POP3(user_login):
>>   >  >         Couldn't init INBOX: Mailbox isn't a valid mbox
>>   >  >      -The mailbox start with either 'FFrom or 'FrFrom'
>>   >
>> We're having the same issues on our servers here and it
>> oddly started at exactly the same time (March 20th or so)
>> with no changes made by us.
>
> How often do they happen? If it really is related to time, the only
> thing I can think of is that daylight saving time changed, which
> increased/decreased some timestamp string and broke some length
> calculation..

It's happening several times a day, sometimes to the same mailbox.  I'm 
not sure if that's a reflection of how busy the mailbox is or not.  It's 
difficult to say how many mailboxes we have being accessed via POP3 
since it only seems to affect those, so I can't give you a percentage.

>> We've upgraded to the latest Dovecot 1.2.11 and are using
>> Dovecot 'deliver' exclusively.  Tried setting
>> fsync_disable=no, but the problem persists.
>
> You could try mbox_lazy_writes=no and mbox_dirty_syncs=no, although
> disabling lazy writing makes the performance worse. Let me know if those
> fix it..

Unfortunately, these didn't help.  We definitely did notice some locking 
issues with those turned off though so we turned them back on once we 
were sure they didn't help with the corruption.

We also noticed some other storage and assertion errors around the same 
time the corruption occurs which may or may not be related:

---
Mar 28 11:24:20 dovecot: POP3(user at home.com): Disconnected:
Storage error during logout. top=0/0, retr=0/0, del=1/35, size=1167453

Mar 26 14:49:36 dovecot: Panic: POP3(user at home.com):
file mbox-sync.c: line 1314 (mbox_sync_handle_eof_updates): assertion
failed: (offset == 0|| offset > 31)

Mar 24 15:21:59 dovecot: POP3(user at home.com): Cached
message offset 2 is invalid for mbox file
/usr/boxes/mailbox
Mar 24 15:21:59 dovecot: POP3(user at home.com):
Disconnected: Storage error during logout. top=0/0,
retr=0/0, del=1/232, size=10622872
---

I'm not sure if "mail_debug=yes" will give us any additional info, but 
I'm turning that on now.

Thanks,
Erik